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  • 1985-1989  (691)
  • 1988  (691)
  • Engineering General  (570)
  • pharmacokinetics  (121)
  • 101
    Digitale Medien
    Digitale Medien
    Plasma drug and antiplatelet profiles of the original acetylsalicylic acid preparations used in the AMIS, PARIS and German-Austrian trials for secondary prevention of myocardial infarction (1988)
    Springer
    European journal of clinical pharmacology 33 (1988), S. 541-547 
    Details
    ISSN: 1432-1041
    Schlagwort(e): acetylsalicylic acid ; infarct prevention ; platelet aggregation ; pharmacokinetics ; healthy volunteers ; secondary heart attack prevention ; AMIS ; PARIS ; German-Austrian trials
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In a cross-over study 6 healthy male subjects were given for 9 days the acetylsalicylic acid (ASA) preparations used in the Aspirin Myocardial Infarction Study (AMIS), Persantine-Aspirin Reinfarction Study (PARIS) and German-Austrian secondary heart attack prevention trials, exactly according to the original study protocols. Plasma concentrations of ASA and its main metabolites salicylic acid (SA) and salicyluric acid (SUA), as well as platelet function (collagen-induced platelet aggregation; tissue extract-induced change in platelet shape) were studied repeatedly on the first day of each medication period and were again examined on the sixth and ninth days. Differences in the plasma concentrations of ASA and its metabolites were found only on the first day, probably as a result of different absorption rates. Collagen-induced platelet aggregation was more rapidly inhibited the faster the preparation was absorbed. Each ASA preparation inhibited tissue extract-induced platelet shape change from the first dose, although statistically significant inhibition was seen only with the AMIS preparation. It is concluded that differences in the antithrombotic efficiency of ASA cannot be explained by differences in the pharmacokinetic and antiplatelet profiles of the various ASA preparations tested.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00542484
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  • 102
    Digitale Medien
    Digitale Medien
    Intrathecal ACNU — a new therapeutic approach against malignant leptomeningeal tumors (1988)
    Springer
    Journal of neuro-oncology 6 (1988), S. 221-226 
    Details
    ISSN: 1573-7373
    Schlagwort(e): leptomeningeal tumor ; intrathecal chemotherapy ; ACNU ; nitrosourea ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Pharmacokinetics, toxicity and therapeutic efficacy of intrathecal ACNU, 3-((4-amino-2-methyl-5-pyrimidinyl)methyl)-1-(2-chloroethyl)-1-nitrosourea, were studied in rats to determine if it is a new and effective method for the treatment of malignant leptomeningeal tumors. Pharmacokinetics of intracisternally administered ACNU was studied by macroscopial autoradiography using 14C-labeled ACNU. It was demonstrated that intracisternally administered ACNU distributed in the subarachnoid space and subpial layer of the brain in high concentration and was rapidly eliminated into the systemic circulation. The diffusional transport of ACNU into the deeper part of the brain was limited. More than 3.0 mg/kg of intracisternal ACNU induced progressive loss of the weight of body in normal rats, and 80% of the rat given 6.0 mg/kg died. Increase of capillary permeability, neuronal loss and gliosis were observed in the marginal layer of the brain facing to the subarachnoid space in the rat given more than 3.0 mg/kg of ACNU. Systemic and local toxicity was not observed in the rat given less than 1.5 mg/kg. Therapeutic effect of intrathecal ACNU against leptomeningeal tumors was evaluated in the rat with meningeal carcinomatosis induced by intracisternal inoculation of Walker 256 carcinosarcoma cells. The median survival time of the rat treated with 1.5 mg/kg of intracisternal ACNU once on day 2 or on day 5 after tumor inoculation was significantly prolonged by 173%, and 214% at maximum, respectively, as compared with that of the untreated animal. These findings suggest that intrathecal ACNU may be of value for clinical trial against leptomeningeal tumors.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00163704
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  • 103
    Digitale Medien
    Digitale Medien
    The use of mass balance principles to describe regional drug distribution and elimination (1988)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 16 (1988), S. 13-29 
    Details
    ISSN: 1573-8744
    Schlagwort(e): pharmacokinetics ; mass balance ; regional distribution ; regional elimination
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Mass balance principles were used to derive a number of terms that are helpful in describing the rate and extent of regional drug uptake. Regional drug uptake was defined as the net movement of drug from the blood perfusing a region into the extravascular space of the region due to the distribution and/or elimination of the drug. By analogy with the traditional physiological definition of flux, net drug flux was defined as the difference in mass per unit time of drug respectively entering and leaving a region via the arterial and venous blood vessels. The timeintegral of net drug flux, net drug mass, was defined as the mass of drug that has entered a region via the arterial blood vessels but has not left the region via the venous blood vessels. For regions in which no drug elimination occurs, the mean regional drug concentration was defined as the net drug mass divided by the mass of the region. When a number of criteria are satisfied, the net drug flux is approximately the rate of drug uptake and the net drug mass is approximately the extent of drug uptake. Several examples are given to demonstrate the broad range of applications of mass balance principles. First, the method was used to characterize the differences between drug distribution and elimination in a hypothetical region using drug concentrations simulated from compartmental models of either distribution alone or distribution with elimination. Second, the whole body distribution net flux was described during a constant rate infusion of iodohippurate (IOH) into a sheep from the difference between the whole body net flux and renal net flux of IOH. Third, the time course of the mean myocardial lignocaine (lidocaine) concentrations in a sheep after an intravenous bolus of lignocaine were described. The time course of the lignocaine-induced depression of myocardial contractility followed more closely the mean myocardial lignocaine concentrations than that of either the arterial or coronary sinus blood concentrations. It is concluded that the use of mass balance principles provides a simple, empirical, and physiologically based method for the determination of the rate and extent of both drug distribution and elimination in regions as simple as single organs or as complex as the whole body.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01061860
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  • 104
    Digitale Medien
    Digitale Medien
    The uptake and elution of lignocaine and procainamide in the hindquarters of the sheep described using mass balance principles (1988)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 16 (1988), S. 31-40 
    Details
    ISSN: 1573-8744
    Schlagwort(e): lignocaine ; procainamide ; pharmacokinetics ; mass balance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract Mass balance principles were used to describe the uptake and elution of lignocaine (lidocaine) and procainamide in the hindquarters of the sheep. Each of four sheep received a right atrial infusion of either lignocaine · HCl (2.7 mg/min) or procainamide · HCl (5.5mg/min) for 180 min. Paired arterial and inferior vena cava (draining the hindquarters) blood samples were taken at 20-min intervals during the infusion and for 180 min after the infusion. Lignocaine and procainamide mean total body clearances were 2.9 L/min (SD 1.1) and 1.3 L/min (SD 0.2), respectively. An index of the uptake and elution of these drugs in the hindquarters was estimated from the net drug mass per unit hindquarter blood flow;indirect evidence suggested that hindquarter blood flow was constant. All the net mass/flow of procainamide that was taken into the hindquarters during the infusion also eluted after the infusion, demonstrating reversible distribution into the tissues. However, uptake of procainamide was still occurring when blood concentrations were constant, indicating that the concentrations of procainamide in the hindquarters were not in equilibrium with the inferior vena cava concentrations. Lignocaine did not reach constant blood concentrations during the infusion and showed no tendency to reach arteriovenous equilibration; an arteriovenous difference of 22%(SD5%) across the hindquarters was measured during the last 60 min of the infusion. By 180 min after the lignocaine infusions, 79% (SD 8%) of the lignocaine net mass/flow had not eluted from the hindquarters when arterial and venous lignocaine concentrations were not significantly different. This drug could remain uneluted due to metabolism and/or avid tissue binding, and presents difficulties in the interpretation of pharmacokinetic data whether based on arterial or venous blood sampling.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01061861
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  • 105
    Digitale Medien
    Digitale Medien
    On the dose dependency of Cyclosporin a absorption and disposition in healthy volunteers (1988)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 16 (1988), S. 331-353 
    Details
    ISSN: 1573-8744
    Schlagwort(e): Cyclosporin A ; pharmacokinetics ; dose dependency ; oral absorption ; disposition ; healthy subjects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract The pharmacokinetics of Cyclosporin A (CyA, SandimmuneR) was studied in 12 healthy male volunteers after oral dosing of 350 mg, 700 mg, and 1400 mg as a drinking solution. Blood samples were collected over 96 hr and analyzed by high pressure liquid chromatography. Concentration data were evaluated with model-independent and model-based linear pharmacokinetic concepts. Individual CyA concentration-time profiles in whole blood were well described by a two-compartment open model with zero-order absorption for all three doses. Comparison of pharmacokinetic parameters across doses indicates that both absorption and disposition are dose-dependent. Nonlinear disposition is suggested by the significant increase of the terminal half-life from 8.9±4.9hr to 11.9±4.9hr (mean±SD) after a 350 mg and a 1400 mg dose, respectively. Changes in the metabolic activity of the liver with concentration might be responsible for this phenomenon. In addition, the modeling approach indicated that bioavailability decreases with increasing dose. Moreover, the dependence of the rate of CyA absorption (zero-order rate constant) versus dose was well described by a hyperbola. The limited solubility of the drug in the gastrointestinal tract might be responsible for this behavior. The lag time (0.2–0.8 hr) was independent of dose. This value is similar to the time of gastric emptying in fasting volunteers. The duration of absorption for 11 of 12 subjects was in the range 2.5–3.5 hr over all doses and agrees well with the small intestine transit time. Some subjects showed a marked secondary peak at one or two doses, which could be adequately fitted by a model with two successive zero-order inputs. This double-peak behavior was ascribed to the influence of the food on gastric emptying. Dose dependency of disposition and absorption counterbalance each other in the usual dose range. This leads to an almost proportional increase of area under the blood CyA concentration-time profile with increasing dose.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01062550
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  • 106
    Digitale Medien
    Digitale Medien
    Pharmacokinetic modeling of the anticonvulsant response of oxazepam in rats using the pentylenetetrazol threshold concentration as pharmacodynamic measure (1988)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 16 (1988), S. 203-228 
    Details
    ISSN: 1573-8744
    Schlagwort(e): oxazepam ; pharmacokinetics ; pharmacodynamics ; anticonvulsant response ; pentylenetetrazol threshold ; kinetic-dynamic model
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract This investigation developed strategies along which the anticonvulsant effect of oxazepam in the rat could be pharmacokinetically modeled. After determination of the pharmacokinetics of oxazepam, which could be described with a two-compartment model (halflives of distribution and elimination 6 and 52 min, respectively), the drug was administered iv to groups of animals to achieve a serum concentration range of 0.1–2.5 mg/L at 10, 45, and 120 min after administration. At these time points pentylenetetrazol (PTZ) was infused slowly until the first myoclonic jerk occurred. The anticonvulsant response, expressed as the elevation of the serum or brain threshold concentration of PTZ, was modeled versus the serum (both total and free) and brain oxazepam concentration, according to the sigmoid E max model. The total serum and brain oxazepam EC50 values are about 0.5 mg/L and 1.1 mg/kg, respectively, and E max 120 mg/L PTZ. No marked differences in pharmacodynamic parameters between the three time groups were found, which indicates that serum and brain are pharmacokinetically indistinguishable from the effect compartment, that there is no (inter) activity of oxazepam metabolites and absence of development of acute tolerance during the investigated time frame. An interfering role of metabolites was also excluded by a direct radioreceptor assay of oxazepam, yielding very similar results as the specific Chromatographic assay. It is concluded that the concentration-anticonvulsant effect relationship of oxazepam can satisfactorily be described by the sigmoid E max model, when utilizing the employed experimental strategies.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01062261
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  • 107
    Digitale Medien
    Digitale Medien
    An Implantable Pump for Intrarenal Infusion of Immunosuppressants in a Canine Autotransplant Model (1988)
    Springer
    Pharmaceutical research 5 (1988), S. 781-785 
    Details
    ISSN: 1573-904X
    Schlagwort(e): pharmacokinetics ; 6-mercaptopurine ; targeted drug delivery ; renal transplantation ; intraarterial infusion
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract We developed a canine renal allograft model utilizing implantable infusion pumps and biocompatible catheters to investigate the pharmacokinetics of local immunosuppressive drug administration. Seven mongrel dogs underwent bilateral nephrectomy and autotransplantation of one kidney to the iliac vessels. The proximal end of an infusion catheter directed into the iliac artery was tunneled to a subcutaneously placed programmable pump. A second, sampling catheter was placed with its tip in the iliac vein. Simultaneous regional (iliac vein) and systemic (jugular vein) venous concentrations of 6-mercaptopurine (6-MP), the immunosuppressive metabolite of azathioprine, were determined during a continuous 24-h intraarterial infusion (10 mg/kg/24 hr). The gradient between regional and systemic 6-MP concentrations was maximal initially when the pump was turned on, continuously decreased until steady state was reached, and disappeared immediately after the pump was turned off. The mean ratio of steady-state iliac vein to systemic 6-MP concentrations was 5.0 ± 1.4, demonstrating a pharmacokinetic advantage of continuous intraarterial 6-MP infusion to the autotransplanted kidney. The novel canine renal allograft model described herein overcomes the technical limitations of earlier models and represents a foundational step in the design of intrarenal infusion patterns of immunosuppressive agents which we expect to prolong survival of the allotransplanted kidney with minimal systemic drug exposure and side effects.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1015940802451
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  • 108
    Digitale Medien
    Digitale Medien
    Liquid Chromatographic Analysis of Di(2-ethylhexyl) Phthalate: Application to Pharmacokinetic Studies in the Mongrel Dog (1988)
    Springer
    Pharmaceutical research 5 (1988), S. 10-15 
    Details
    ISSN: 1573-904X
    Schlagwort(e): di(2-ethylhexyl) phthalate ; liquid chromatographic (LC) analysis ; pharmacokinetics ; renal failure ; mongrel dog
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract A high-performance liquid chromatographic (HPLC) assay was developed for the determination of di(2-ethylhexyl) phthalate (DEHP) in serum or plasma. Plasma DEHP concentrations that were measured by HPLC in specimens obtained from hemodialysis patients were in good agreement with corresponding concentrations that were measured by gas chromatography with selected ion monitoring (GC-SIM) (r 2 = 0.996). Plasma DEHP concentrations were measured after intravenous DEHP administration (1.2–4.4 mg DEHP/kg body weight) to determine the effect of bilateral ureteral ligation on DEHP elimination in the mongrel dog. DEHP plasma clearance (∼6.3 ml/min/kg), steady-state distribution volume (∼0.2l/kg), and terminal half-life (∼50 min) were unchanged in two dogs following bilateral ureteral ligation. DEHP terminal half-life and steady-state distribution volume were substantially smaller (25- to 70-fold) than reported previously in the rat or dog.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1023/A:1015872309411
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  • 109
    Digitale Medien
    Digitale Medien
    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250101
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  • 110
    Digitale Medien
    Digitale Medien
    Error estimation and adaptivity in flow formulation for forming problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 23-42 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A very simple and reliable error estimator has recently been developed for problems of linear elasticity.1 This leads naturally toa predication of an h-mesh refinement required for a given accuracy and with a suitable mesh generator2 for an efficient adaptive process. In this paper we extend the methodology developed previously to incompresible plastic flow of metals or polymers using the ‘flow formulation’ approach.3The examples of application include steady state extrusion problems for which exact solutions are available and hence allow the efficiency of the error estimates to be tested as well as more complex problems of upsetting in which the mesh is updated. It is found that the estimator performs well under various circumstances and provides an economical adaptive process.
    Zusätzliches Material: 19 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250105
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  • 111
    Digitale Medien
    Digitale Medien
    Ignition phase transition of a polymer: Convective exposure (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 373-386 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The ignition of a semi-infinite solid polymer under convective exposure is investigated. A quasi-steady approximation is used for the gas phase and the transient effect is accounted for in the solid phase only. Both surface and gas phase chemical reactions are included simultaneously. The ignition mechanism is studied in terms of the concurrent heat transfer, mass transfer, mass transfer and chemical processes at the surface as well as in the gas phase. The gas phase governing equations are integrated independently from the solid phase energy equation using the Adams-Moulton subroutine. Corrections to the iterative procedure are carried out by establishing a set of perturbation equations and using the Newton-Raphson and least-squares methods. The results indicate that ignition occurs in the heterogeneous mode within a narrow range of low flow velocities and high temperatures. An ignition phase transition point exists, and within a wide range of high flow velocities, ignition switches to the homogeneous mode.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250208
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  • 112
    Digitale Medien
    Digitale Medien
    Shape design sensitivity analysis for non-linear anisotropic heat conducting solids and shape optimization by the BEM (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 109-120 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Shape design sensitivity analysis (SDSA) expressions have been derived for non-linear anisotropic heat conducting solid bodies by following the material derivative concept and adjoint variable method of optimal shape design given in the literature. The variation of a general integral functional has been described in terms of primary and adjoint quantities evaluated at the varying boundaries. As an example problem in shape optimization, optimal outer boundary profiles of an orthotropic solid body are obtained by the boundary element method (BEM), after reformulating the SDSA equations in a form which is most suitable for the BEM.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260108
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  • 113
    Digitale Medien
    Digitale Medien
    Analyses of steady-state visco-elastic fluids using the penalty function method (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 43-54 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The application of the penalty-function formulation of the finite element method is made possible for analysing visco-elastic fluid flows by the method which decouples the momentum and continuity equations from the constitutive equation. An upwind finite element scheme is combined with the method in order to solve the constitutive equation. As visco-elastic fluid models, Jaumann derivative, upper and lower convected derivatives are considered. The Poiseuille flow and the flow through a plane converging channel are analysed.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250106
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  • 114
    Digitale Medien
    Digitale Medien
    Approximate methods for analysing the cold drawing of polymeric fibres and films (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 99-112 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Approximate methods for analysing steady-state cold drawing processes in polymer forming are discussed. These methods are applied to both axisymmetric and plane-strain drawing. The cold drawing process is associated with steady-state neck propagation along the specimen. Modifications are introduced in the approximate steady-state analysis which reflect the neck initiation and localization phases prior to steady-state drawing. This is accomplished without resorting to an analysis of the entire load-deformation history of the process. Finite element results are also presented and compared with those of the proposed approximate analyses. These comparisons show the approximate analysis to be an extremely efficient and quite accurate computational scheme for the analysis of steady-state cold drawing processes.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250110
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  • 115
    Digitale Medien
    Digitale Medien
    Analysis of stress and strain distributions in slab rolling using an elastic-plastic finite-element method (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 55-66 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The cold rolling of rectangular section slabs is analysed for a range of width-to-height ratios (one to three) for which spread of the workpiece is appreciable. This necessitates the use of a three-dimensional model. An elastic-plastic finite-element method is used to provide a complete description of the slab rolling process.The pressure distribution at the workpiece/roll interface is found to show the typical ‘friction-hill’ observed in near-plane-strain experiments, but the pressure varies across the width of the interface. The shear-stress distribution at the roll interface provides detailed information about the ‘neutral line’ which is usually assumed to occur where the shear stress changes direction. The 3-D analysis shows clearly that there is a flow divide in both longitudinal and transverse directions.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250107
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  • 116
    Digitale Medien
    Digitale Medien
    Numerical simulation of the densification behaviour of metal powder during hot isostatic pressing (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 213-225 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A numerical method is introduced which is based on metal flow theory and simulates the densification of metal powder during hot isostatic pressing.The method, in which nodal velocities are variables, takes into consideration the dependence of flow stress on the temperature, strain rate and relative density of the material. The compressibility of porous metal as well as the incompressibility of fully dense metal are also taken into account.Porous specimens of the superalloy MERL76 were subjected to uniaxial compression tests at high temperature in order to determine the parameters of the equations on which the method is based. The densification behaviour of a turbine disk and two cylindrical components was numerically simulated and compared with experimental results.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250117
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  • 117
    Digitale Medien
    Digitale Medien
    Preface (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. i 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250202
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  • 118
    Digitale Medien
    Digitale Medien
    Coarse-fine mesh method for heat and mass transfer in locally complex flows (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 347-355 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Combined forced and free convective flows having locally complicated geometries or boundary conditions were numerically studied with a finite difference method of coarse and fine meshes. The coarse-and-fine mesh method developed can be used for numerical calculations of both unsteady and steady processes of heat and mass transfer in convective and diffusion flows which are strongly influenced by locally fine flows. The method was applied to a numerical calculation of the steady flow field of a CVD (chemical vapour deposition) reactor which has locally complicated flows caused by small inlet nozzles. The results of the calculation showed a considerable contribution of locally fine flows to the overall flow field, which is well predicted with the present method.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250206
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  • 119
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    Digitale Medien
    Thermal analysis of human body-clothing-environment system (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 357-371 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: For the solution of thermal comfort problems a coupled model is presented consisting of the thermal model of the human body and of the clothing, with boundary conditions of the third kind.For thermal modelling the human body is divided into 16 parts according to the special character of the internal heat generation, of the blood vessel system and of the sweat secretion mechanism. Part models are connected by the flow paths of arteries and veins.Transport phenomena in the clothing are treated by a coupled heat and mass transfer model which permits various kinds of clothing for the different parts of the body.The equation system of the full model has been solved numerically by using time stepping schemes. As the results of the computations an approximative temperature field of the human body is produced.Calculated results have been compared with Experimental data.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250207
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  • 120
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    Digitale Medien
    Finite element simulation of hot isostatic pressing of metal powders (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 191-212 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Rate form constitutive equations of elasto-viscoplastic type are expressed in a manner similar to that of classical metals, but the viscoplastic part, which is no longer incompressible, is related to the rate of variation of porosity. An incremental and implicit algorithm has been implemented in a finite element program in order to simulate hot isostatic pressing of an Astroloy powder. Temperature distributions are shown to induce strong density variations in real parts during hot isostatic pressing (HIP). For one particular turbine disk, we tested the sensitivity of the final shape to different processing parameters. Computed final shapes compare well with experimental ones.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250116
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  • 121
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    Digitale Medien
    Analysis of bending effects in sheet forming operations (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 253-267 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The majority of work in numerical analyses of sheet metal forming operations is based on the simple membrane-shell theory which neglects the effect of sheet bending. While useful information can be extracted from these analyses, especially for stretch-dominated operations, the membrane theory is basically inadequate for analysing the draw-type operations where sheet metal bends, slides and unbends over a draw radius.This paper presents axisymmetric and plane-strain finite element analyses of stretch/draw of sheet metal over a die corner radius. Numerical solutions obtained from a total Lagrangian formulation of a finite-strain thin shell theory are used to indicate the relative significance of including the bending effects in various simple forming operations. Comparisons of the calculated results with available experimental data are also given.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250119
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  • 122
    Digitale Medien
    Digitale Medien
    A finite element simulation of the sheet metal forming process (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 283-292 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A finite element simulation code of the sheet metal forming process has been developed. This simulation code plays an important role in the computer aided engineering (CAE) system for an automobile parts forming process, which includes the pre- and post-processes. The paper presents the development of an updated Lagrangian type finite element modelling, based on the elastic-plastic (J2 flow law) membrane shell theory. An attempt is made to calculate the strain distribution incurred by peripherally clamped or non-clamped square plates when impressed by rigid punches. These are the cases of square box-shape punch drawing and arbitrary shaped panel stretch forming.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250121
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  • 123
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    Digitale Medien
    Punch stretching of sheet metal and differential equations on manifolds (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 269-282 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The goal of mathematical modelling of sheet metal forming processes is to provide predictive tools for use in the design of stamping processes and the selection of sheet materials. Most current approaches to finite element modelling of large deformation, elastic-plastic sheet metal forming problems use a rate form of the virtual work (equilibrium) equations, and a single-field finite element representation of the displacement components. Called the incremental method, this approach does not produce approximations which satisfy the discrete equilibrium equations at all times, and consequently it demands small time steps to insure stability and numerical accuracy. This paper describes a variant of the mixed method in which displacements, stresses, effective strain and pressures are all given separate finite element representations. The equilibrium equations in non-rate form are discretized to produce a system of algebraic equations which are coupled with the constitutive equations and then integrated using state-of-the-art numerical software. When used to model rate sensitive sheet materials in hydrostatic bulging, plane strain punch stretching and hemispherical punch stretching, the new approach proved to be between 6 and 26 times as fast as the old incremental method.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250120
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  • 124
    Digitale Medien
    Digitale Medien
    Buoyant flow calculations with non-orthogonal curvilinear co-ordinates for vertical and horizontal parallelepiped enclosures (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 331-345 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A control-volume-based finite-difference formulation is developed for heat transfer and fluid flow in arbitrary three-dimensional parallelepiped enclosures. The governing equations in Cartesian co-ordinates are first transformed to those in non-orthogonal curvilinear co-ordinates by tensor transformations. After introducing the properties of the parallelepiped geometry, equations are obtained in the primitive variables for which all vectors and tensors are based on the curvilinear co-ordinates. With proper treatment of the heat flux and stress tensor terms, the finite-difference equations, analogous to those in the Cartesian coordinates, are formed. Examples are utilized to show the validity of the methodology and the results are found to compare well with existing experimental data. The differences in heat transfer and fluid flow inside parallelepiped enclosures and rectangular enclosures are delineated and discussed from a physical point of view.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250205
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  • 125
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    Digitale Medien
    Finite element analysis of turbulent forced convection in lid-driven rectangular cavities (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 313-329 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Turbulent fluid flow and heat transfer in lid-driven rectangular cavities are analysed by a finite element procedure for the prediction of the turbulent forced convection in two-dimensional recirculating flows. The (k-ε) model is used to compute effective viscosities and thermal conductivities. The fluid flow and turbulence model parabolic equations are solved sequentially, one after the other. Then, the calculated velocity distribution is used in the solution of the steady state energy equation to yield the temperature field. Aspect ratios e=0·75, 1·0 and 1·5 and Reynolds numbers ranging from 5 × 104 to 4 × 105 are considered in the numerical examples.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250204
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  • 126
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    Digitale Medien
    Non-linear simulation of dendritic solidification of an undercooled melt (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 415-444 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Two-dimensional finite element simulations of solidification for quiescent undercooled pure metals are presented. The full non-linear, transient heat equation is used with phase front tracking which is subject to local curvature and interfacial kinetics. During early stages of the waveform instability the simulated solutions match the linear stability analysis with fidelity. Beyond the valid range of that analysis the numerical solution continues to demonstrate the physically observed exponential growth behaviour and characteristic spacing between fingers. Whereas the simulations show the sensitivity of dendritic growth to initial conditions, as expected for an unstable process, the overall pattern formation preserves the characteristic spacing. The simulations are terminated after the onset of bifurcation. Thereafter, the numerical model is inappropriate for physical comparison owing to the planar, two-dimensional limitation.
    Zusätzliches Material: 24 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250211
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  • 127
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    Digitale Medien
    A regular indirect boundary element method for thermal analysis (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 495-515 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A Regular Indirect Boundary Element formulation is developed following a weighted residual approach. In this formulation, the fictitious source density, which appears in the integral equations of the method, is distributed on a surface which is exteriorly separated from the physical field boundary of the problem. This approach does not require the evaluation of singular integrals and produces undeteriorated solutions at geometric discontinuities. The formulation is presented here as applied to two dimensional and axisymmetric thermal problems. It includes a different subregioning scheme which treats each subregion, of a multidomain problem, separately, thereby eliminating the need for a sophisticated reduction scheme.
    Zusätzliches Material: 24 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250214
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  • 128
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    Digitale Medien
    Warping torsion in thin-walled open section beams using the semiloof beam element (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 231-243 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Many structural members including metallic, reinforced polymer and concrete members must be modelled, in the simplest approximation, as thin-walled beams whose cross-sections exhibit significant, out-of-plane warping owing to torsion. The elastic capabilities of the semiloof beam element are extended to include warping torsion of thin-walled open section beams. The performance of the extended element is compared with that of the original formulation.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260116
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  • 129
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    Digitale Medien
    Partial eigensolution of damped structures by non-linear optimization (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 143-152 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The partial solution of damped structures involves the determination of only a few of the resonant frequencies and corresponding damping characteristics and mode shapes. The procedure outlined here uses a modification of the variable metric solution algorithm, in which the dicision variables are elements of the complex eigenvector and the eigenvalue. The quadratic eigenvalue problem is reformulated as a sequential unconstrained minimization problem. Both normality and orthogonality constraints are incorporated in the objective function. The method is compared to an adaptation of the subspace iteration technique, also applicable to the quadratic eigenvalue problem.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260110
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  • 130
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    Digitale Medien
    An element-by-element method for heat conduction CAE including composite problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 199-215 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Mechanical computer aided engineering (CAE) implies large finite element problems due to the geometric complexity of the ‘true’ 3D designs. Application of the standard finite element technique is not practical for such problems because the direct solution of the global matrix equations is too costly. This paper considers the element-by-element implicit algorithm for the CAE application of transient heat conduction. The direct solution is avoided by an operator splitting or approximate factorization technique. This results in both the execution time and storage requirements for each time step being linearly proportional to the number of elements while retaining unconditional stability. However, the approximate factorization introduces additional truncation error and incorrect jump conditions at material interfaces. Detailed analyses and numerical experiments are carried out in one dimension to assess the nature and mechanism of these inaccuracies. A three dimensional implementation is then compared with one dimensional results. The need for an additional predictor-corrector element-by-element algorithm for 3D composite problems is also presented.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260114
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  • 131
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    Digitale Medien
    Letters to the editor (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 281-282 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260119
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  • 132
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    Digitale Medien
    Conference diary (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 291-292 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260124
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  • 133
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    Digitale Medien
    Plastic design. An imposed hinge-rotation approach, P. Zeman and H. M. Irvine, Allen & Unwin, London, 1986, 86, pages (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 290-290 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260123
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  • 134
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    Digitale Medien
    Finite elements and solution procedures for structural analysis. vol. I: Linear analysis. M. A. Crisfield, Pineridge Press, Swansea, 1986. No. of pages: 272 (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 289-289 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260122
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  • 135
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    Digitale Medien
    Hybrid finite element-Monte Carlo method for coupled conduction and gas radiation enclosure heat transport (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 361-378 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A hybrid two-dimensional finite element-Monte Carlo numerical solution method has been developed for solving complex transient non-linear gas radiation enclosure problems. Solid conducting media are coupled to conducting gaseous or particulate participating media and both may be internally energy generating. Bilinear isoparametric elements are used, allowing geometrically complex enclosures with internal objects to be present. Radiative energy transport within the gaseous enclosures is accounted for using a Monte Carlo method which permits a broad range of complexities. Included here are: diffuse-grey and specularly reflecting walls with temperature and spectrally dependent, and non-homogeneous emissivities or absorptivities; absorbing/emitting gases with temperature and spectrally dependent, and non-homogeneous emissivities or absorptivities; and isotropic or anisotropic scattering gases or particles. This method was verified by solving several standard steady state problems and comparing the solutions to those found using the conventional finite element, the P-N and the exchange factor methods. Solution times are comparable to those of the finite element method. A more complex transient problem solution is then given to demonstrate the versatility and power of the method.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260206
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  • 136
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    Digitale Medien
    Derivatives of eigenvalues and eigenvectors of a general complex matrix (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 293-311 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A survey of methods for sensitivity analysis of the algebraic eigenvalue problem for non-Hermitian matrices is presented. In addition, a modification of one method based on a better normalizing condition is proposed. Methods are classified as Direct or Adjoint and are evaluated for efficiency. Operation counts are presented in terms of matrix size, number of design variables and number of eigenvalues and eigenvectors of interest. The effect of the sparsity of the matrix and its derivatives is also considered, and typical solution times are given. General guidelines are established for the selection of the most efficient method.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260202
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  • 137
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    Digitale Medien
    Convergence of curved shell elements based on assumed covariant strain interpolations (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 329-347 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A C0 9-node shell element based on assumed interpolations of covariant strain components defined with respect to the element natural co-ordinate system has recently been proposed. In this formulation, the covariant strains are obtained directly from the Cartesian strains by tensor transformation without any need to compute laminar co-ordinate based strains. In the present work, the interpolated covariant strains used in this element are analysed to determine their satisfaction of the basic requirements for successful strain interpolation. These basic requirements are stated as invariance to rigid body motions and ability to represent constant and linear strain states. In the finite element formulation, the weak form of momentum balance is expressed in terms of covariant strains and contravariant stresses. The corresponding elasticity tensor is a function of the components of the metric tensor associated with the element natural co-ordinate system. The invariance properties of the metric tensor in the context of the finite element approximation are also discussed.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260204
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  • 138
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    Digitale Medien
    Spline collocation in the flow of non-Newtonian fluids (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 413-421 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Natural convection flow of a non-Newtonian fluid between two vertical infinite parallel flat plates forms the case study of the present work. Velocity profiles for the Prandtl-Eyring and Powell-Eyring fluid models are obtained through the method of spline collocation.The applicability and reliability of the techniques employed here are discussed in detail with a suggested error estimate and analysis. Accuracy in the successive iterations in the results is of the fourth order. To maintain this accuracy the help of a computer is not required for carrying out the calculation of velocity profiles. Thus the simplicity of the spline collocation technique is demonstrated in its application to flow problems.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260209
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  • 139
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    Digitale Medien
    Computation of hybrid element matrices by elimination techniques (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 423-435 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Three functionals, the modified forms of the Hu-Washizu, Hellinger-Reissner, and complementary energy principles, as developed by Pian, Chen, and Kang1.2 are stated. Finite element discretization of each is presented and the ensuing computations developed, resulting in the element stiffness matrix, with displacement degrees-of-freedom only, and the stress recovery matrices. Subroutines are presented for this purpose where the close relationship of the three principles is exploited to result in a compact hybrid element technique. The techniques herein reviewed are assumed applicable at the individual element level. The usual summation over all elements in the model is implied.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260210
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  • 140
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    Digitale Medien
    Accuracies of numerical solution methods for the pressure-modified von Mises modelThe paper was presented at Tenth U.S. National Congress of Applied Mechanics, June 16-20, 1986, Austin, Texas, U.S.A. (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 453-465 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The accuracy of three numerical algorithms - the tangent-stiffness radial-return, secant-stiffness radial-return and simple radial-return methods - is analysed against exact solutions for the pressure-modified von Mises yield criterion with the associated flow rule. The governing equations of the exact solutions are derived using a simple and innovative geometrical approach, in terms of a pair of non-linear, first order differential equations, in rate change of the deviatoric radius and in rate change of angular locations on the deviatoric plane. For both accuracy and efficiency, and for small and large time steps, the secant-stiffness radial-return method is the best of all.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260212
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  • 141
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    Three-dimensional elastic finite element study of the skid resistance of grooved pavement (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 437-452 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A three-dimensional finite element model has been developed to simulate the sliding of a rubber block over a grooved road surface. The model makes use of the symmetries of the problem to simplify the analysis, so that two-dimensional isoparametric elements of both rectangular and triangular configuration have been extended into the third dimension. A procedure for analysing the behaviour of any one groove to groove unit of the pavement is also developed, and this is extended so that the contact between the sliding rubber block and the leading edge of each raised pavement section is analysed. Preliminary comparisons between theoretical calculations and experimental measurements indicate that the finite element procedure provides an accurate and economical estimate of the behaviour of the rubber slider as it is pressed into a grooved pavement. Elastic predictions of sliding resistance seem reasonable at low sliding speeds, but viscoelastic rubber analysis appears necessary if higher speed skid resistance is to be predicted.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260211
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  • 142
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    Analysis of steady free convection from an axisymmetric heat-generating body embedded in a semi-infinite porous medium (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 467-487 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An analysis is presented for the steady state free convective flow and heat transfer from an axisymmetric heat-generating body that is embedded in a fluid-saturated, semi-infinite, porous medium. The porous medium is assumed to be rigid, homogeneous and isotropic, and be in thermal equilibrium with the fluid. The fluid is assumed to be incompressible, with the density changes contributing only towards the buoyancy forces via the Boussinesq approximation. The governing equations for the fluid consist of the equation of continuity, Darcy's law and the equation of energy. After introducing the stream function concept, the equations governing the stream function and pressure are derived. Using the non-dimensional variables, the non-dimensional equations governing the non-dimensional forms of the temperature, stream function and pressure are dervied and the appropriate boundary conditions are stated. The mathematical formulation contains two parameters; D, the non-dimensional depth of the body from the surface of the porous medium, and a product Raθs of Rayleigh number (Ra) and the non-dimensional surface temperature of the body (θs). The Galerkin finite element method, with linear, isoparametric, quadrilateral elements, is used to reduce the mathematical formulation into a set of algebraic equations. The expressions to calculate the non-dimensional surface temperature and Nusselt number of the body, and the non-dimensional velocity of the fluid, are derived. A computer code has been developed to solve the algebraic equations, using Gauss elimination procedure, in a banded matrix form. The computer code, in addition to the non-dimensional temperature, stream function and pressure, calculates the isothermal lines, non-dimensional surface temperature of the body, Nusselt number of the body, velocity field and isobars.To demonstrate the application of the code, a spherical heat-generating body is considered as an example. Numerical results are obtained for D = 3 and 6, and Raθs = 0.001, 0.1, 1 and 5, and presented.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260213
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  • 143
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    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260301
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  • 144
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    Announcements (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 527-530 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260217
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  • 145
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    An integrated approach to the synthesis of geometrically non-linear structures (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 555-570 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An integrated approach to the minimum weight design of geometrically non-linear three dimensional truss structures with geometric imperfections, subject to inequality constraints on static displacements, stresses, local buckling and cross sectional areas, is investigated. The integrated structural synthesis problem involves design and response quantities as independent variables and equilibrium equations, describing the finite element model, as equality constraints. The non-linear structural analysis and the optimization are thus merged together into a single process. A computer program developed to compute the contraint values and analytical gradients is coupled with a generalized reduced gradient algorithm to solve the integrated problem. Numerical results for a geometrically non-linear shallow dome example problem are presented for various types of imperfections. Furthermore, it is found that the algorithm is capable of detecting and guarding against system as well as element elastic instability using equilibrium information only, that is, without imposing system and local buckling inequality constraints.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260304
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  • 146
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    Digitale Medien
    Theoretical basis of the finite element iterative method for the eigenvalue problem in stationary cracks (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 531-539 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: In a recently published paper a finite element based iterative method was introduced for the solution of the eigenvalue problem of stationary cracks.1 In this paper we give the theoretical basis of this iterative method and we show why it converges and how it could be extended to more complex fracture problems. The cases of cracks at interfaces are illustrated.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260302
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  • 147
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    Digitale Medien
    Application of the finite element iterative method to the eigenvalue problem of a crack between dissimilar media (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 541-554 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The finite element iterative method is applied to the eigenvalue problem of a crack between dissimilar media. In this case the transfer matrix is non-symmetric, which leads to complex eigenvalues. The singularity obtained agrees with the analytical results of r(-1/2+ie). The method of evaluating the eigenfunctions is general and can be applied to more complex cases of material and geometry, which are frequently encountered in composite materials. A powerful method for evaluating stress intensities in dissimilar media is given in the Appendix. The method is also reduced for homogeneous media to give stress intensity factors for modes I, II and III.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260303
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  • 148
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    Digitale Medien
    Elasto-plastic large deformation analysis of space-frames: A plastic-hinge and stress-based explicit derivation of tangent stiffnesses (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 589-615 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper deals with elasto-plastic large deformation analysis of space-frames. It is based on a complementary energy approach. A methodology is presented wherein: (i) each member of the frame, modelled as an initially straight space-beam, is sought to be represented by a single finite element, (ii) each member can undergo arbitrarily large rigid rotations, but only moderately large relative rotations; (iii) a plastic-hinge method, with arbitrary locations of the hinges along the beam, is used to account for plasticity, (iv) the non-linear bendin-stretching coupling is accounted for in each member, (v) the applied loading may be non-conservative and (vi) an explicit expression for the tangent stiffness matrix of each element is given under conditions (i) to (v). Several examples, with both quasi-static and dynamic loading, are given to illustrate the accuracy and efficiency of the approaches presented.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260306
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  • 149
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    Digitale Medien
    Multi-grid solutions to the elastic plastic torsion problem in multiply connected domains (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 631-646 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The elastic plastic torsion problem for an elastic, perfectly plastic cylinder with multiply connected cross section twisted around its longitudinal axis is formulated as an obstacle problem for an associated stress potential, the obstacle being defined in terms of a generalized distance function. Based upon the reformulation of the obstacle problem as an equivalent linear complementarity problem, the latter is discretized by means of finite difference techniques, and a monotonically convergent iterative scheme for its numerical solution is developed. At each step of the iteration the solution of a reduced system of discrete Poisson equations is required which is done by applying multi-grid techniques with respect to a hierarchy of grid-point sets. Combined with a suitably chosen nested iteration process this results in a computationally very efficient algorithm for the approximate solution of the elastic plastic torsion problem.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260308
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  • 150
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    Digitale Medien
    Application of spline strip method to analyse vibration of open cylindrical shells (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 663-676 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper deals with the vibration of open cylindrical shells by the spline strip method based on Novozhilov's shell theory. Convergence of the solutions is investigated in a few examples and is found to be satisfactory. The accuracy of the results is compared with those calculated by other numerical methods and found to be in good agreement.The effect of inlcuded angles and inplane constraints on vibrating characteristics of simply supported cylindrical shells is shown.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260310
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  • 151
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    Digitale Medien
    A quadrilateral finite element including vertex rotations for plane elasticity analysis (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 717-730 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A finite element of arbitrary quadrilateral shape is presented for plane elasticity analysis. The element is derived from triangular fields of compatible quadratic displacements with vertex connectors which include rotations. All rigid body movements and constant strain states are recovered exactly. Results from several test problems demonstrate that very good numerical accuracy is obtained for both displacements and stresses, even for quite coarse finite element meshes.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260314
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  • 152
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    Digitale Medien
    A numerical case study of a non-Newtonian flow problem (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 695-704 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper addresses some of the theoretical aspects involved in the numerical study of non-Newtonian flow problems. We consider the second-order Rivlin-Erickson constitutive model due to the simple differential form that emerges for the system of equations that govern the flow when expressed in stream function-vorticity variables. This model describes slightly elastic fluids that exhibit a constant viscosity behaviour. A steady two-dimensional flow is studied through a planar contraction geometry.An auxiliary variable is introduced into the problem formulation producing a non-linear system of differential equations comprising two elliptic equations and one hyperbolic equation. This system is discretized by finite difference methods and the resulting system of non-linear algebraic equations is solved iteratively by successive substitutions. The simple structure of this iteration permits a convergence analysis which is presented in Section 2. This analysis is performed prior to the spatial discretization and establishes the dependence of the iteration upon the material parameters. At the discrete linearized equation level a combination of inner iterations for elliptic equations and direct marching for the hyperbolic equation is used. The stability of the marching scheme is considered in Section 4.3 and a discussion on the results is given in Section 5.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260312
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  • 153
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    Digitale Medien
    A nine node finite element for analysis of geometrically non-linear shells (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1945-1962 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A nine node finite element is presented for the analysis of thin shell structures undergoing large deflection. The finite element formulation is based on the concept of degenerate solid shell element and the Hellinger-Reissner principle with independent strain. Three versions of assumed independent strain are selected to suppress spurious kinematic modes. One version leads to a finite element model which is kinematically stable at element level while the other two give globally stable models. Numerical tests indicate that the finite element model which is stable at element level may reveal the locking effect in certain cases. However, the other two models are free of locking.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260905
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  • 154
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    Digitale Medien
    Finite element approximations of singular parabolic problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1989-2007 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An efficient implementation of finite element methods for free boundary parabolic problems in general two dimensional space domains is presented. The Stefan problem, the Hele-Shaw problem and the porous medium equation are included. Backward differences or linearization techniques are used for the time discretization of the problem. The performances of these schemes are discussed with several numerical tests.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260907
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  • 155
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    Digitale Medien
    A new hybrid transfinite element computational methodology for applicability to conduction/convection/radiation heat transfer (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1087-1100 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper describes new and recent advances in the development of a hybrid transfinite element computational methodology for applicability to conduction/convection/radiation heat transfer problems. The transfinite element methodology, while retaining the modelling versatility of contemporary finite element formulations, is based on application of transform techniques in conjunction with classical Galerkin schemes and is a hybrid approach. The purpose of this paper is to provide a viable hybrid computational methodology for applicability to general transient thermal analysis. Highlights and features of the methodology are described and developed via generalized formulations and applications to several test problems. The proposed transfinite element methodology successfully provides a viable computational approach and numerical test problems validate the proposed developments for conduction/convection/radiation thermal analysis.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260507
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  • 156
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    Digitale Medien
    A robust triangular plate bending element of the Reissner-Mindlin type (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1169-1184 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A new triangular plate element is presented. This new element is based on independent interpolations for slopes, displacement and shear forces, and it is shown that it does not suffer from any defect common to other Mindlin plate elements. Several examples are presented to illustrate the behaviour of this new element.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260511
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  • 157
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    Digitale Medien
    Computer analysis of structures matrix structural analysis, structured programming, Siegfried M. Holzer, Elsevier, 1985, pp. 426. ISBN 0-444-00943-4 (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1235-1236 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260515
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  • 158
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    Formulation and solution of hierarchical finite element equations (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1213-1233 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The paper presents a general hierarchical formulation applicable to both elliptic and hyperbolic problems. Static and eigenvalue linear elastic problems as well as convection-diffusion problems are studied. The hierarchical formulation is well suited for adaptive procedures.For the convection-diffusion problem the hierarchical approximation is made in time only. Different hierarchical functions are proposed for different types of problems. Both weighted residual and least-squares formulations are applied. A combination of these two gives a penalty method with a constraint equation corresponding to the least-squares method. A whole class of time integration formulae is obtained. These are all suitable for adaptive procedures owing to the hierarchical approximation in the time domain. If a linear discontinuous hierarchical base function is used in the Galerkin weak formulation, the method so obtained corresponds to the discontinuous Galerkin method in time and is especially suited for convection dominated problems. The streamline-diffusion method is found to be the aforementioned penalty method.This paper also examines the sequence of nested equation systems that results from a hierarchical finite element formulation. Properties of these systems arising from static problems are investigated. The paper presents some new possibilities for iterative solution of hierarchic element equations, and different procedures are compared in a numerical example. Finally, a simple ID convection-diffusion problem clearly shows that the proposed hierarchical formulation in time gives a stable and accurate solution even for convection dominated flow.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260514
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  • 159
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    Digitale Medien
    Announcement (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1240-1240 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260518
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  • 160
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    Digitale Medien
    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260601
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  • 161
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    Digitale Medien
    Exact numerical solutions for radiative heat transfer in cylindrical furnaces (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1201-1212 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Exact expressions for the distributions of the components of radiative flux density and the radiative energy source term in terms of wall and medium temperature distributions have been formulated for an emitting absorbing medium of constant properties bounded by black walls of a cylindrical enclosure. The accuracy of numerical solutions has been tested on an idealized enclosure for which exact analytical solution of the expressions is possible and shown to have six-figure accuracy. The exact expressions have then been solved numerically for an enclosure problem based on data reported previously on a large scale experimental furnace. The principal feature of the data is highly non-uniform temperature distributions which are typical of the conditions encountered in industrial furnaces. These data have been chosen because of their practical importance and the non-availability of exact solutions for such data. The resulting exact solutions have been tabulated and are intended to serve in the future as standards for testing the accuracy of the approximate predictions produced using various three-dimensional flux models in cylindrical configurations.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260513
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  • 162
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    Three-dimensional finite element analysis of open-die forging (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 67-85 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Three-dimensional finite element analysis is applied to operation sequences in open-die forging. Flat tools with rounded edges for open-die forging are geometrically modelled using Bézier curves. With this technique, the problems at the die-workpiece interface, such as the integration of frictional stress, node touching on dies and node separating from dies, can be handled effectively. It is shown that in solving general symmetric problems computation time can be saved by reducing variables and rearranging them in the stiffness matrix. One-bite operations and operation sequences for producing two-size bars and two-size pipes in several bites are investigated in regard to geometry, load, energy and deformation distribution.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250108
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  • 163
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    Digitale Medien
    On the development of a general purpose finite element program for analysis of forming processes (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 113-131 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 20 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250111
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  • 164
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    Digitale Medien
    On the use of the boundary element method for elastoplastic, large deformation problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 165-176 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The boundary element method is applied to large deformation problems typical in industrial forming problems. A form of Betti's theorem relevant to an updated Lagrangian type of solution procedure is established as the basis for the boundary element formulation. Equilibrium iterations are needed in each load step. All non-linear terms are moved to the right-hand side and the boundary element method can be used. Cross-anisotropy is assumed where Hill's yield criterion is adopted together with isotropic hardening. The investigation has shown that the boundary element method is applicable to this type of problem, giving good results within reasonable computer time.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250114
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  • 165
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    Digitale Medien
    Transient analysis of forging operations by the pseudo-concentration method (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 177-189 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The pseudo-concentration method is used to follow the flow of metal during the transient analysis of an axisymmetric forging problem. The technique requires a minimum of user interaction and appears to be ideal for computer aided design of dies. An analysis of an engine disc blocker die is presented and compared with experimental results. The same problem is analysed using a Newtonian fluid which is shown to give good qualitative results which would be acceptable in the initial stages of die design.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250115
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  • 166
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    Digitale Medien
    Plastic and viscoplastic flow of void-containing metals. Applications to axisymmetric sheet forming problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 227-251 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A formal analogy between the equations of pure plastic and viscoplastic flow theory for void-containing metals and those of standard non-linear elasticity is presented. The formulation is particularized for the analysis of axisymmetric sheet metal forming problems using simple two node linear finite elements. Details of the treatment of friction and strain hardening phenomena, time increment computation and elastic effects are also given. Examples of the effect of void porosity on the hemispherical stretching of a circular sheet are presented.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250118
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  • 167
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    Digitale Medien
    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250201
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  • 168
    Digitale Medien
    Digitale Medien
    Computation of low-speed compressible flows with time-marching procedures (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 293-311 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The extension of time-marching procedures to low Mach number and low Reynolds number conditions is considered. It is shown that the disparate speeds of the acoustic and particle waves prevent convergence at high Reynolds numbers, while the requirement that both the Courant and the von Neumann numbers be of order one prevents convergence in very viscous flows. A perturbation expansion is used to introduce pseudo-acoustic waves that propagate at speeds similar to the particle speed at high Reynolds numbers and that allows both the inviscid and viscous time step parameters to be of order one at low Reynolds numbers. The resulting algorithm is shown to give convergence rates that are independent of either Mach number or Reynolds number over a range of five orders of magnitude in both parameters. Results are shown for strong heat addition in low-speed flow encompassing this broad range of variables.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250203
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  • 169
    Digitale Medien
    Digitale Medien
    Optimization of actively controlled structures using goal programming techniques (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 183-197 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The problem of design of actively controlled structures subject to restrictions on the damping parameters of the closed-loop system is formulated and solved as a multiobjective optimization problem. The purpose of control is to effectively suppress structural vibrations due to initial excitation. The cross-sectional areas of the members are treated as design variables. The structural weight and the controlled system energy are considered as objective functions for minimization. The goal programming approach is used for the solution of the multiobjective optimization problems. The procedure is illustrated through numerical simulations using two-bar and twelve-bar truss structures.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260113
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  • 170
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    Digitale Medien
    A numerical study of laminar and turbulent flows in a two-dimensional bend with or without a guide vane (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 245-262 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A numerical study of the flow in a two-dimensional 90° circular-arc bend is presented. The study is based on the solution of the governing equations using a finite volume technique. Both laminar and turbulent flows are considered. Particular attention is given to the occurrence and size of the separation regions and, in this respect, the effects of Reynolds number and bend radius to height ratio are discussed. The study includes the effect of a guide vane, placed in the bend, on the flow characteristics. It is shown that the emerging velocity distribution is more uniform than that associated with flow in a bend without a guide vane. The presence of a guide vane is shown to suppress the formation of regions of flow separation. Comparisons are made between the effects on the flow of two different designs of guide vane.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260117
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  • 171
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    Digitale Medien
    Letters to the editor (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 283-287 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260120
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  • 172
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    Digitale Medien
    Analysis of infilled frames using A coupled finite element and boundary element solution scheme (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 731-742 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The behaviour of infilled frames subjected to horizontal loads is analysed by an iterative numerical procedure. The stiffness of the structural system is determined with variations in geometrical and mechanical characteristics.The analysis is carried out utilizing the boundary element method (BEM) for the infill and opportunely dividing the frame into finite elements, so as to transform the mutual interactions of the two subsystems into stresses distributed along the boundary for the infill and into nodal actions for the frame.This makes it possible to take into account the separation arising between the two substructures when mutual tensile stresses are involved.At first, infills without openings are considered, using BEM with constant elements for two-dimensional problems in elasticity.The results are compared with those obtained using the simplified equivalent pin-jointed strut model, which is very common in the literature.Subsequently, using an analogous procedure, panels with openings are considered. For these systems, for which no satisfactory simplified models exist, the loss of stiffness in relation to the size of the opening is evaluated.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260315
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  • 173
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    Digitale Medien
    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260401
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  • 174
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    Digitale Medien
    Announcements (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 766-767 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260318
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  • 175
    Digitale Medien
    Digitale Medien
    Generalized hybrid-combined methods for the singularity problems of homogeneous elliptic equations (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 785-803 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Combinations of the Ritz-Galerkin and finite element methods are applied to solving singularity problems of homogeneous, elliptic equations. The Ritz-Galerkin method is used in the subdomains where there exist singular points; and the finite element method is still used in the rest of the solution domains. More general coupling techniques than those of Reference 6 along the common boundary of subdomains are discussed. Numerical experiments using these kinds of coupling techniques are provided for the first time. It is interesting that the calculated results of Motz's problem have shown the simplified hybrid strategy in Reference 6 to be optimal for both error bounds and stability of numerical solutions, among all general coupling techniques.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260403
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  • 176
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    Digitale Medien
    Spectral collocation methods for the primary two-point boundary value problem in modelling viscoelastic flows (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 805-813 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Expansions in terms of beam functions and Chebyshev polynomials are used to compute solutions to the primary two-point boundary value problem within a spectral collocation formulation. The performance of the methods is analysed in terms of accuracy and robustness relative to the level of non-linearity. Accurate results are obtained with Chebyshev polynomials and the performance of these trial functions is insensitive to the level of non-linearity whereas the behaviour of the beam functions shows great sensitivity to the level of non-linearity. The use of Newton's method to solve the mixed linear-non-linear system for the Chebyshev coefficients is successful for highly non-linear problems without the need for parameter continuation.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260404
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  • 177
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    Digitale Medien
    The null space and non-conventional basis functions in the mixed finite element method (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 843-855 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The two matrix equations obtained from the mixed finite element method are uncoupled through the use of the QR decomposition. The procedure obtains the basis for the null space which is composed of solutions to the homogeneous flux-equilibrium equation. The result is that, even for statically indeterminate problems, stresses can be obtained without solving for the displacement field. Furthermore, the stress field can be decomposed directly into contributions from applied forces and from prescribed displacements. The appearance of kinetic modes can easily be monitored. The possibility of utilizing non-conventional basis functions for use in conjunction with the QR decomposition is explored briefly. Simple examples are given to illustrate the theoretical results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260407
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  • 178
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    Digitale Medien
    A parallel householder tridiagonalization stratagem using scattered row decompositionThis paper presents one phase of research carried out at the Jet Propulsion Laboratory, California Institute of Technology (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 857-873 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Householder's method for tridiagonalizing a real symmetric matrix, a major step in evaluating eigenvalues of the matrix, is modified into a parallel algorithm for a concurrent machine of message passing type. Each processor of the concurrent machine has its own CPU, communications control and local memory. Messages are passed through connections between processors. Although the basic algorithm is inherently serial, the computations can be spread over all processors by scattering different rows of the matrix into processors, hence the term “Scattered Row Decomposition”. The steps in the serial and the parallel algorithms are identified. Expressions for efficiency and speedup are given in terms of problem and machine parameters. For a concurrent machine of ring type interconnection, a selected representative problem of large order exhibits efficiency approaching 66 per cent.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260408
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  • 179
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    Digitale Medien
    Multi-domain BEM for two-dimensional problems of elastodynamics (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 891-911 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An advanced implementation of the boundary element technique for the periodic and transient dynamic analyses of two-dimensional elastic or visco elastic solids of arbitrary shape and connectivity is presented. For transient dynamic analysis the problem is first solved in the Laplace transform space and then the time domain solutions are obtained by numerical inversion of transformed domain solutions.The present analysis is capable of treating very large, multi-domain problems by substructuring and satisfying the equilibrium and compatibilities at the interfaces. With the help of this substructuring capability, problems related to the layered media and soil-structure interaction can all be analysed. This paper also introduces a new type of element called ‘Enclosing Element’, which has been developed and used to model the infinitely extending boundaries of a half-space or a layered medium. A number of numerical examples are presented, and through comparisons with available analytical and numerical results, the accuracy, stability and efficiency of the present analysis are established.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260410
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  • 180
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    Digitale Medien
    A full range analysis of reinforced concrete slabs using finite elements (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 973-985 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper describes a full range analysis of reinforced concrete slabs, which includes the effects of both geometric and material non-linearities, using the finite element method. A computer program is described which has been used to analyse slabs previously tested by a number of investigators. The comparisons between the test results and the computer program are considered to be good.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260414
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  • 181
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    Digitale Medien
    Announcements (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1003-1003 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260417
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  • 182
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    Digitale Medien
    Remarks on computational magnetostatics (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 987-1000 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A two-scalar-potential formulation for magnetostatic computations has been recommended4 based on a comparative study of several different formulations in terms of their accuracy and efficiency. A different study3 challenged this recommendation. It is the purpose of this report to present results which confirm the practical necessity for the two-potential formulation.The method used for the present study was to construct a simplified computer program designed to easily compare the alternative methods. This program uses the finite element method on a geometry suited for analysis of the ‘bifiliar conductor’ problem treated in both studies mentioned above. In this program, the alternative formulations are implemented with a great deal of common code. In particular, the input, stiffness matrix, matrix solution and editing routines are common to both formulations, with differences appearing only in the source terms for the stiffness matrix equation. The known analytic solution to this particular problem provides a reference with which the computed solutions is compared. The main conclusion of this study of the ‘bifiliar conductor’ problem is that for a given choice of mesh, the two-potential formulation yields significantly more accuracy than the reduced-potential formulation.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260415
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  • 183
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    Digitale Medien
    Finite element simulation of long and short circular die extrusion experiments using integral models (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 9-22 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Streamline Elements ; KBKZ Model ; LDPE Extrusion ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A finite streamline element method for use with integral type constitutive equations in viscoelastic flow simulation, including thermal effects, is presented and some new results using this method in modelling the IUPAC extrusion experiments for low-density polyethylene (LDPE), involving both long and short circular dies, are reported and discussed. It will be shown that the special streamline-based elements provide a convenient way of particle tracking and strain tensor calculation. The extrusion calculation when using a relatively realistic KBKZ type integral model with multiple relaxation times is stable, and practically important Weissenberg numbers and swelling ratios have been reached without difficulty. The agreement with experimental swelling ratios is on the whole satisfactory. In order to make the model a good fit to the Trouton viscosity experimental data of the LDPE sample, a spectrum of elongational parameters has been introduced. The second normal stress term has also been added to the integral model to examine its effect on extrusion swelling. The non-isothermal effects and the possibility of a wall slip near the die exit at high apparent shear rates are also discussed.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250104
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  • 184
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    Digitale Medien
    Finite-element modelling of metal flow in three-dimensional forming (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 87-97 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A fully three-dimensional elastic-plastic finite-element program for the study of metalforming operations is described. Several applications are discussed, and the finite-element (FE) predictions of metal flow, strain rate and temperature distributions, and the sites of initiation of ductile fracture are presented.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250109
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  • 185
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    Finite element computation of bulging in continuously cast steel with a viscoplastic modelPresented at the 2nd International Conference on ‘Numerical Methods in Industrial Forming Processes’. Gothenburg. Sweden, 1986. (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 147-163 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The bulging of continuously cast steel between the support rolls has been computed using a viscoplastic finite element model. Both two-dimensional and three-dimensional models are based on the minimization of the functional associated with the Norton-Hoff law and use the streamlines integration to calculate the bulging. By using industrial data, the influence of both numerical parameters and process parameters on the extent of the calculated bulging values has been investigated. The comparison of our results with experimental measurements confirms the relevance of the hypothesis of viscoplastic behaviour.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250113
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  • 186
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    Digitale Medien
    The influence of non-linear thermal parameters on moisture content distributions in unsaturated soil (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 263-279 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The influence of non-linear thermal parameters on moisture distribution predictions in an unsaturated soil is investigated. A fully non-linear numerical model of coupled heat and mass transfer is used to analyse the one dimensional drying of a stratum of loam. The distribution of moisture content in the upper 0.5 m of soil is the subject of interest. Assumed representative material parameters are used.The results show small but significant changes in moisture content variations when either the value of the thermal conductivity or the heat capacity alone is kept constant. When both are held constant, however, a cancellation of effects occurs. This is attributed to the fact that the thermal gradients in the soil remain largely unchanged when compared with fully non-linear values. Actual magnitudes of temperatures are different but the thermal gradients are not.These conclusions cannot be generalized at this stage beyond the problem dependent results achieved. The results are, however, viewed as a contribution to a greater overall understanding of the complex problem under consideration.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260118
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  • 187
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    Digitale Medien
    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260901
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  • 188
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    Digitale Medien
    Conference diary (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 763-765 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260317
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  • 189
    Digitale Medien
    Digitale Medien
    A least squares finite element formulation for elastodynamic problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1883-1891 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A residual finite element formulation is developed in this paper to solve elastodynamic problems in which body wave potentials are primary unknowns. The formulation is based on minimizing the square of the residuals of governing equations as well as all boundary conditions. Since the boundary conditions in terms of wave potentials are neither Dirichlet nor Neumann type it is difficult to construct a functional to satisfy all governing equations and boundary conditions following the variational principle designed for conventional finite element formulation. That is why the least squares technique is sought. All boundary conditions are included in the functional expression so that the satisfaction of any boundary condition does not become a requirement of the trial functions, but they should satisfy some continuity conditions across the interelement boundary to guarantee proper convergence. In this paper it is demonstrated that the technique works well for elastodynamic problems; however, it is equally applicable to any other field problem.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260813
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  • 190
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    Digitale Medien
    Reliable use of determinants to solve non-linear structural eigenvalue problems efficiently (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1825-1841 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A ‘multiple determinant parabolic interpolation method’ is described and evaluated, principally by using a plane frame test-bed program. It is intended primarily for solving the transcendental eigenvalue problems arising when the ‘exact’ member equations obtained by solving the governing differential equations of members are used to find the eigenvalues (i.e. critical buckling loads or undamped natural frequencies) of structures. The method has five stages which together ensure successful convergence on the required eigenvalues in all circumstances. Thus, whenever checks indicate its suitability, parabolic interpolation is used to obtain eigenvalues more rapidly than would the popular bisection alternative. The checks also ensure a wise choice of the determinant used by the interpolation. The determinants available are all usually zero at eigenvalues, and comprise the determinant of the overall stiffness matrix Kn and the determinants which result, with negligible extra computation, from effectively considering all except the last m (m=1, 2,…, n-1) freedoms to which Kn corresponds as internal substructure freedoms. Tests showed time savings compared to bisection of 31 per cent when finding non-coincident eigenvalues to relative accuracy ∊ = 10-4, increasing to 62 per cent when ∊ = 10-8. The tests also showed time savings of about 10 per cent compared with an earlier Newtonian approach. The method requires no derivatives and its use in the widely available space frame program BUNVIS-RG has demonstrated how easily it can replace bisection, which was used in the earlier program BUNVIS.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260810
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  • 191
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    Digitale Medien
    Hierarchic plate and shell models based on p-extensionThis paper is dedicated to Professor Ivo Babuša on the occasion of his sixtieth birthday. A summary of the work reported herein was presented at a conference at which Professor Babuša was honoured for his numerous contributions in the fields of engineering and applied mathematics. The conference, entitled: ‘The Impact of Mathematical Analysis on the Numerical Solution of Engineering Problems’, was held at the University of Maryland, College Park, MD September 17-19, 1986. (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 1855-1881 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: This paper is concerned with formulations of finite element models for beams, arches, plates and shells based on the principle of virtual work. The focus is on computer implementation of hierarchic sequences of finite element models suitable for numerical solution of a large variety of practical problems which may concurrently contain thin and thick plates and shells, stiffeners, and regions where three dimensional representation is required. The approximate solutions corresponding to the hierarchic sequence of models converge to the exact solution of the fully three dimensional model. The stopping criterion is based on (1) estimation of the relative error in energy norm; (2) equilibrium tests and (3) observation of the convergence of quantities of interest.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260812
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  • 192
    Digitale Medien
    Digitale Medien
    Numerical simulation of the transport processes in a heat treatment furnace (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 387-399 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The numerical simulation of the heat transfer and fluid processes in a furnace is carried out using finite difference techniques. A heat treatment furnace for the annealing of steel is considered as an example and a mathematical model of the system is obtained by simplifying the equations that govern the transport in the various components that constitute the system. The resulting set of coupled equations then governs the time-dependent temperature distribution in the furnace. Because of the complexity of the full problem, the transport processes undergone by individual components of the furnace are simulated first, using appropriate boundary conditions that decouple them from the other components. These individual simulations are considered in terms of the underlying physical mechanisms for validation. Finally, these are combined to obtain the simulation of the full, coupled problem. The temperature cycle undergone by the material is computed, along with the time-dependent temperature distributions in other components. A comparison with experimental data indicates close agreement, lending strong support to the numerical model. The relevance of these results to the design of the overall thermal system is also outlined.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250209
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  • 193
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    Digitale Medien
    On the numerical modelling of heat transfer during solidification processes (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 445-473 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: An extensive amount of work has been published on the treatment of heat transfer associated with phase change. A few recent advances are discussed in this paper with some emphasis on the phase change of metals. The apparent capacity, effective capacity, enthalpy, post iterative, source based and semi-analytical methods are discussed and relative advantages and disadvantages of each are analysed. Recent developments in nodelling the flow during pouring and natural convection with applications of two widely used convective liffusive codes, the Los Alamos MAC and the Imperial College TEACH, are presented. An alternative tream function-vorticity approach is also discussed. Applications of these methods to turbulent convection during mould filling and continuous casting are presented. Areas of interest for further research work are identified as modelling of turbulence in liquid metals, flow through mushy regions and improvement of the performance of weak methods in multidimensional problems when the ratio of latent heat to sensible heat is large.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250212
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  • 194
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    Digitale Medien
    Solution accuracies of finite element reentry heat transfer and thermal stress analyses of space shuttle orbiter (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 517-543 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: Accuracies of solutions (structural temperatures and thermal stresses) obtained from different finite element thermal and structural models set up for the space shuttle orbiter are compared and discussed. For studying the effect of element size on the solution accuracies of finite element heat transfer and thermal stress analyses of the orbiter, five structural performance and resizing (SPAR) thermal models and five NASA structural analysis (NASTRAN) structural models were set up for the orbiter wing midspan bay 3. The structural temperature distribution over the wing skin (lower and upper) surface of one bay was dome shaped and induced more severe thermal stresses in the chordwise direction than in the spanwise direction. The induced thermal stresses were extremely sensitive to slight variation in structural temperature distributions. Both internal convention and internal radiation were found to have equal effects on the orbiter structural temperatures. Minimum degrees of element fineness required for thermal and structural models for the orbiter to yield satisfactory solutions were established. In transient heat transfer analysis most of the computation time was consumed in the time-dependent temperature calculations and not in the radiation view-factor computations.
    Zusätzliches Material: 23 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250215
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  • 195
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    Digitale Medien
    Failure of mechanically loaded laminated composites subjected to intense localized heating (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 561-570 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: A numerical procedure is presented for predicting failure in laminated composites subjected to simultaneous intense localized heating and applied mechanical loads. The method consists of a non-linear two-dimensional, axisymmetric finite difference thermal analyser which considers the effects of surface ablation, radiation and convection losses and temperature dependent thermophysical properties. The thermal results are used in conjunction with a flat plate finite element code to predict the failure of laminated composites. Predictions based on the numerical analyses are compared with experimental results obtained from mechanically loaded graphite epoxy coupons spot-irradiated at various intensities.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250217
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  • 196
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    Digitale Medien
    Some novel techniques for the finite element analysis of heat and mass transfer problems (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 611-624 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The coupled heat and mass transfer partial differential equations as derived by Luikov are used to analyse freezing problems in porous media. A numerical model is subsequently developed to depict the frost heave mechanism in a freezing soil system. An example is given of the application of the model and the results are compared with those achieved from field experiments.Also, a novel application of the coincident node technique is presented for the coupled heat and mass transfer problem. This circumvents the numerical problems usually associated with flow through thin layers, in this case a vapour barrier, sandwiched between materials of greater thickness.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250221
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  • 197
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    Digitale Medien
    Deformations and stresses in welding of shell structures (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. 635-655 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The simulation of welding of shell structures is investigated in this paper. In order to verify the implementation of the shell element adopted, two different problems were studied. In the first problem the butt-welding of two plates was simulated. In the second problem the butt-welding of a thin-walled pipe was simulated. It is concluded from the analysis of the plate problem that the shell element is quite effective in the membrane state. The comparison between calculated values and experimental values for the residual stress field in the pipe shows that the shell element performs quite well in the analysis of a realistic problem.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250223
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  • 198
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    Digitale Medien
    Masthead (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988) 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260101
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  • 199
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    Digitale Medien
    Variable-order variable-step algorithms for second-order systems. Part 2: The codes (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 26 (1988), S. 55-80 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: In a companion paper, Thomas and Gladwell,4 the authors designed a class of multistage methods for second-order systems of ordinary differential equations (ODE's), together with local error estimators based on embedding techniques. Here we provide a set of subroutines implementing the algorithms and discuss our numerical experience with the resulting codes.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620260105
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  • 200
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    Digitale Medien
    Preface (1988)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 25 (1988), S. i 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620250102
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