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  • Electronic Resource  (314)
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  • Electronic Resource  (314)
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  • 1980-1984  (277)
  • 1965-1969  (37)
  • 1920-1924
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 64 (1982), S. 381-391 
    ISSN: 1573-5036
    Keywords: Atmosphere ; Calcium ; Fertility ; Forestry ; Magnesium ; Nitrogen ; Nutrients ; Phosphorus ; Pinus caribaea ; Potassium ; Savanna ; Sodium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Fertility levels in soils beneathPinus caribaea trees were examined in the Mountain Pine Ridge savannas, Belize, where fire control has precipitated the development of pine woodland. Slight surface soil enrichment was recorded beneath pine canopies, but to levels well below those found beneath associated hardwoods. Estimates of total nutrient pools beneath trees showed modest cation accumulation beneath a 73 year old tree but some defecits in Ca and Mg beneath a 24 year old tree. A tap root cutting experiment on trees of the same species revealed no significant declines in foliar nutrient levels after 19 months. It is concluded that no pronounced long-term deterioration in soil fertility levels is developing beneath stands ofP. caribaea in the savanna, although some temporary nutrient declines may exist beneath young pine stands. Atmospheric inputs are the most likely source of nutrient accretion and it is suggested that the establishment of hardwood associates with pine may enhance the rates of nutrient capture from this source.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 65 (1982), S. 429-432 
    ISSN: 1573-5036
    Keywords: Dry-seeded rice ; Nitrogen ; Oryza sativa L. ; Phosphorus ; Semi-arid environment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Under semi-arid conditions, three field experiments were conducted at Gezira Research Station to determine response of irrigated dry-seeded rice (Oryza sativa L. var IR 2053-206-1-3-6) to addition of nitrogen and phosphorus fertilizers. The experimental treatments included the factorial combinations of seven levels of nitrogen applied as urea and four levels of phosphorus applied as super phosphate. Plant growth and grain yield were significantly and progressively increased with the rise in the levels of added nitrogen and phosphorus. However, response to added phosphorus was restricted by the applied level of nitrogen. The responses of grain yield to nitrogen and phosphorus levels are given by quadratic regression equations. Without addition of nitrogen or phosphorus grain yield averaged 1.52 t/ha compared to 6.07 t/ha with addition of the optimal levels (160 kg N plus 35 kg P/ha). The high potential for rice production in semi-arid environment is evidently restricted by addition of relatively high rates of nitrogen and phosphorus.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5036
    Keywords: Farmyard manure ; Gypsum ; Iron ; Manganese ; Phosphorus ; Rice ; Rice husk ; Sodic soil ; Submergence ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Effect of amendments, gypsum (12.5 tonnes/ha), farmyard manure (30 tonnes/ha), rice husk (30 tonnes/ha) and also no amendment (control) on the availability of native Fe, Mn and P and applied Zn in a highly sodic soil during the growth period of rice crop under submerged conditions was studied in a field experiment. Soil samples were collected at 0, 30, 60 and 90 days of crop growth. Results showed that extractable Fe (1N NH4OAC pH 3) and Mn (1N NH4OAC pH 7) increased with submergence upto 60 days of crop growth but thereafter remained either constant or declined slightly. Application of farmyard manure and rice husk resulted in marked improvement of these elements over gypsum and control. Increases in extractable Mn (water soluble plus exchangeable) as a result of submergence and crop growth under different amendments were accompanied by corresponding decreases in easily reducible Mn content of the soil. Application of 40 kg zinc sulphate per hectare to rice crop could substantially raise the available Zn status (DTPA extractable) of the soil in gypsum and farmyard manure treated plots while the increase was only marginal in rice husk and control plots indicating greater fixation of applied Zn. Available P (0.5M NaHCO3 pH 8.5) behaved quite differently and decreased in the following order with crop growth: gypsum〉rice husk〉farmyard manure〉control.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 68 (1982), S. 19-32 
    ISSN: 1573-5036
    Keywords: Iron ; Lupins ; Lupinus albus L. ; Manganese ; Phosphorus ; Proteoid root ; Soil/Root interface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary It has been demonstrated by an agar film technique thatL. albus can cause the breakdown of colloids of iron/silicate, iron/phosphate, aluminium/silicate and aluminium phosphate and destabilise suspensions of manganese dioxide, calcium mono-hydrogen phosphate and ferric hydroxide. Dissolution of these compounds was most marked in areas adjacent to proteoid roots (dense clusters of secondary laterals of limited growth which develop on lateral roots) and parts of the tap root. Soil associated with these regions of the root system contained more reductants and chelating agents than the bulk soil. Soil from around the roots ofL. albus exhibited much greater reducing and chelating activity than that associated with the roots of rape and buckwheat.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5036
    Keywords: Glomus fasciculatum ; glycine max ; Mycorrhiza ; Phosphorus ; Soybean ; VAM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Soybean plants colonized by the vesicular-arbuscular mycorrhizal (VAM) fungusGlomus fasciculatum were grown in pot cultures utilizing a composite greenhouse rooting medium. Development of fungal mycelia inside and outside the host root and total fungal biomass were determined from assays of fungal chitin. Growth and phosphorus uptake by VAM plants and uncolonized controls were compared. Mycotrophic growth in VAM plants occurred during the final six weeks of the 19-week growth period, when the concentration of available soil P fell below 10 μg P/g soil. Growth enhancement was most pronounced in the reproductive organs. The data suggest a relationship between the initiation of the reproductive phase in the host and the cessation of growth in the endophyte. Source-sink relationships and P availability appear to be factors influencing interactions between the symbionts.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 69 (1982), S. 105-118 
    ISSN: 1573-5036
    Keywords: Calcium ; Fertility ; Forestry ; Magnesium ; Nitrogen ; Nutrients ; Phosphorus ; Pinus caribaea ; Potassium ; Savanna
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Concentrations of P, N, K, Ca, and Mg in above-ground tissues ofP. caribaea were sampled in the species'native savanna habitat. Concentrations were relatively low, but some evidence of higher consumption of K and Ca was found in trees grown on more fertile soils. Regressions were developed to predict the quantities of nutrients sequestered in above-ground tree tissues, and estimates made of the quantities stored in above-ground stands of this species in its native habitat and in several plantations elsewhere. Estimates were also made of the nutrient removals to be expected by harvesting these stands in different ways. Nutrient quantities stored in stands generally exceed those extractable from savanna surface soils, and it is suggested that inputs from the atmosphere are the most probable alternate nutrient source. A comparison of these inputs for tropical areas with the quantities required for stand growth in the savanna, and harvesting removals, suggests that an adequate supply of all elements except P exists, provided that capture by pine is effective. However, atmospheric inputs generally fall below the storage and harvest removal rates for fast growing exotic plantations of this species suggesting that multiple rotations of these plantations at current growth rates may not be feasible without artifical fertilization.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 69 (1982), S. 131-134 
    ISSN: 1573-5036
    Keywords: Alluvial soil ; Copper ; Interaction ; Iron ; Manganese ; Moisture ; Phosphorus ; Rice ; Waterlogging ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Laboratory incubation experiments were conducted with three clay loam lowland rice soils (Haplustalf) to study the effect of application of three different levels of Cu(0, 1.25, 2.5 ppm) and Mn (0, 10, 20 ppm) in all possible combinations on the changes in the DTPA extractable Zn, Cu, F, Mn and Brays 2 extractable P in soil. The results showed that application of Cu decreased the content of extractable Zn, Fe, Mn and P in soils, the rate of decrease gradually declining with the progress of incubation period. Application of Mn also depressed the content of extractable Cu, Fe and P but increased that of extractable Zn.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 65 (1982), S. 433-436 
    ISSN: 1573-5036
    Keywords: Copper-nutrition ; Nitrogen ; Phosphorus ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary In a pot culture study, copper addition to soil increased the crop yield only in presence of nitrogen. The latter increased the utilization of both native as well as applied copper but more that of applied. It also minimised the adverse effect of applied phosphorus on copper utilization. Phosphorus at the rate 45 ppm had the tendency of decreasing copper uptake by wheat if applied without nitrogen or with its low level.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 68 (1982), S. 33-41 
    ISSN: 1573-5036
    Keywords: Iron ; Lupins ; Lupinus albus L. ; Manganese ; Phosphorus ; Proteoid roots ; Soil/root interface
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The development of proteoid roots byLupinus albus was studied under glasshouse conditions in acid-washed sand with varying iron and phosphorus supply and in three contrasting soils (acid, neutral and alkaline) at a range of phosphorud levels. Aqueous extracts of soil from around the roots were compared with regard to their pH and their reducing and chelating activity. In both experiments, proteoid formation was predominantly affected by the phosphorus status of the plant. Manganese uptake in the second experiment was related to proteoid root development and decreased as phosphorus supply increased. The ability ofL. albus to utilise soil and added phosphorus decreased as pH of the soil increased.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 69 (1982), S. 265-273 
    ISSN: 1573-5036
    Keywords: Azotobacter chroococcum ; Fertilizers ; Farmyard manure ; Nitrogen ; Nitrogen fixation ; Potassium ; Phosphorus ; Yields of grain stover ; Zea mays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Field trials were conducted during theKharif seasons of 1979 and 1980 to examine the effect of the nitrogen-fixing bacteriumAzotobacter chroococcum (isolate M4) on yields of maize and N-economy. Different levels of nitrogen and farmyard manure (FYM) were supplied to assess their interaction with Azotobacter inoculation. Seed inoculation without fertilization raised grain and stover yields significantly. FYM coupled with inoculation gave higher yields than either could singly. The financial gain due to an increase in grain yield upon applying per ha 80 kg N, 10×103 kg FYM and Azotobacter over the treatment 40N + FYM + Azotobacter was offset by the cost of the additional N; thus, the higher N-application was not economical. Azotobacter inoculation was economically most efficient at lower doses of fertilizer nitrogen which not only increased yields but resulted in a saving of fertilizer N when applied in combination with FYM.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 69 (1982), S. 275-280 
    ISSN: 1573-5036
    Keywords: Azotobacter chroococcum ; Fertilizers ; Farmyard manure ; Zea mays ; Maize ; Nitrogen ; Nitrogen fixation ; Phosphorus ; Potassium ; Total nitrogen uptake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The economic feasibility of using cultures of nitrogen fixing microorganisms in programmes to increase crop production, as a selfgenerating source of nitrogen, has been proved beyond doubtviz. Legume-Rhizobium symbiosis and blue green algal ‘fertilizer’ for rice. The extent to which the free living, N-fixing, aerobic, heterotropicAzotobacter chroococcum could replace the application of nitrogenous fertilizer to maize was investigatedin vivo. Total nitrogen uptake (kg ha−1) by maize after inoculation with Azotobacter combined with moderate applications of nitrogen fertilizer and farmyard manure was influenced significantly and resulted in a higher nitrogen concentration in grain and stover along with a higher yield.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 66 (1982), S. 233-241 
    ISSN: 1573-5036
    Keywords: Barley ; Chloride ; Phosphorus ; Salinity ; Sulphate ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The study was conducted in a greenhouse and under field conditions. In the greenoouse, barley was grown to maturity in pots on a sandy soil which contained 80 and 120 meq/l of chloride and sulphate dominant salts in its saturation extract, to which 0, 10, 25 and 50 ppm P were added. In the field study, wheat was grown on loamy sand soils having 0, 25, 50 and 75 kg/ha added P levels and irrigated with either Cl- or SO4-dominant saline waters (EC=15−19 mmhos/cm). The results of the greenhouse study indicated that at maturity barley straw and grain yield was significantly increased by 50 ppm of added P both on the non-saline control and the Cl-treatments. However, 25 ppm P was optimal on the SO4-treatments. The Cl content of plants was significantly decreased and S was increased with the increase in the P content of soil. A synergistic relation between the S and P content of barley shoots was observed. In the field study wheat grain yield responded significantly to P applications upto 50 kg/ha level on the Cl-site and there was no response to applied P on the SO4-site, although the former contained more Olsen's P than the latter. The results suggested that P requirement of wheat and barley was greater on Cl- than on SO4-salinity.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1573-5036
    Keywords: Copper ; Manganese ; Molybdenum ; Phosphorus ; Rice ; Waterlogging ; Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Laboratory incubation experiments were conducted with low-land rice soil to study the effect of applying three different levels of molybdenum (0, 2.5 and 5.0 ppm) and phosphorus (0, 100 and 200 ppm), in all possible combinations, on the changes in available Mo, P, Mn, Zn and Cu in soil. The results showed that application of Mo at both the levels increased the content of extractable Mo and P but decreased those of Cu and Mo in soil whereas application of Mo at higher level only increased the content of extractable Zn in soil. Application of P at both the levels decreased the content of extractable Mo, Mn and Cu but increased that of P whereas it showed an inconsistent effect on the extractable Zn content in soil. The P × Mo interaction effect was found to be beneficial for the content of P, Mo and Zn only. During the initial period of incubation all elements except Cu recorded an increase but with the progress of incubation period the content of all the elements except Mn gradually declined.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1573-5036
    Keywords: Copper ; Manganese ; Molybdenum ; Phosphorus ; Rice Zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The effect of phosphorus and molybdenum alone and combined, on the uptake and utilization of Mo, Mn, Zn, Cu and P by rice (Var. IR-579) was studied in the greenhouse at varying levels of Mo (0, 2.5 and 5.0 ppm) and (0,100 and 200 ppm). Application of P increased the dry matter yield of shoot and root. Combined application of P and Mo increased the dry matter yield of shoot. Application of Mo increased the concentration of Mo and P in shoot. Applied P caused an increase in the concentration of Mo, Zn and P in shoot. Combined application of P and Mo resulted in an increase in concentration and uptake of Mo in shoot.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 69 (1982), S. 3-11 
    ISSN: 1573-5036
    Keywords: A-value ; E-value ; Farmyard manure ; Isotopes ; L-value ; Phosphorus ; Soil phosphorus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary E-, L-values growing mungbean and A-values growing maize, mungbean, urdbean and cowpea were assessed in P and farmyard manure enriched soil of permanent manurial trial at Pantnagar, Nainital of India. E- and L-values were found to increase in farmyard manure and P enriched soil while L-values remained constant at different dates of harvesting. A-values varied with fertility status of soil and the kip of crop. Maize gave higher A-values than pulses. In all crops, higher A-values were found with enrichment of farmyard manure and phosphorus. E-, L- and A-values gave significant correlations with yield and P uptake in pot experiments. E-, L- and A-values were good in assessing the availability of soil phosphorus. However, E-value is a rapid technique as it measured in laboratory without involvement of plant.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 69 (1982), S. 199-212 
    ISSN: 1573-5036
    Keywords: Calcareous ; Eucalyptus obliqua ; Iron availability ; pH ; Phosphorus ; Soil acidulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Glasshouse experiments have shown that the application of an acidulating agent to a calcareous soil can increase growth and alleviate severe chlorosis in an acidic population ofE. obliqua. In contrast, a calcareous population showed only a slight response to this treatment and maintained adequate growth and a low frequency of chlorosis on both control and treated calcareous soils. Foliar analyses of seedlings of the acidic population showed that alleviation of chlorosis was concomitant with a reduction in the levels of P, Ca and K, and an increase in uptake of Fe. However, the total Fe content of foliage was poorly correlated with the occurrence of severe chlorosis. Although this evidence suggested that the differential susceptibility ofE. obliqua to lime-chlorosis can be reduced by increasing the availability of Fe, the greater concentration of Fe in chlorotic seedlings indicated that lime-chlorosis may also be due to an inactivation of Fe within the plant (i.e. by P). This hypothesis was partly confirmed by a water culture experiment which showed that a combination of relatively high pH and high external levels of P could induce severe chlorosis in seedlings of the acidic population. In contrast, it appears that the calcareous population has a more efficient mechanism for absorbing Fe and holding it in an available form, even when external concentrations of P are high. It is suggested that plants which have an efficient mechanism for the uptake of Fe at relatively high pH and are less susceptible to the detrimental effects of P have been selected for on these alkaline calcareous soils.
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  • 17
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982) 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 41-66 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A system for describing three-dimensional surfaces in a form suitable for finite element analysis is described. The system makes extensive use of real-time interactive computer graphics techniques for both input and display. Discrete transfinite mappings are used as the mathematical basis for the surface representation. The mathematical basis and the reasons for choosing this form of representation are discussed. Explicit forms of the mappings based on Lagrange polynomial interpolation functions are presented. Finally, the interactive graphics procedures for defining finite element meshes are described.
    Additional Material: 21 Ill.
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  • 19
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 99-109 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Two highly accurate implicit Padé approximations to the transient heat conduction equation are investigated using the conjugate gradient method to solve, for the temperatures. The accuracy and stability of the approximations are discussed and numerical examples are presented showing the relative performance. Comparisons with the Crank-Nicolson method are also presented.
    Additional Material: 4 Ill.
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  • 20
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. i 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 21
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 195-210 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A clearer insight into the ‘shear locking’ phenomenon, which appears in the development of C0 continuous element using shear-flexible or penalty type formulations, is obtained by a careful study of the Timoshenko beam element. When a penalty type argument is used to degenerate thick elements to thin elements, the various approximations of the shear related energy terms act as different types of constraints and, depending on the formulation, two types of constraints which are classified as true or spurious may emerge. The spurious constraints, where they exist, are responsible for the ‘shear locking’ phenomenon, and its manifestation and elimination is demonstrated in a very simple example. The source of difficulty is shown to be the mathematical operations involved in the various shape function definitions and subsequent integration of functionals. It is seen that formulations that ensure only true constraints in the extreme penalty limit cases display far superior performance in the thick element situation as well, and thus guidelines for the development of efficient elements are drawn. A similar type of behaviour is observed in a shallow curved beam element and here ‘inplane locking’ can be eliminated by selective integration to obtain an improved curved beam element. However, ‘inplane locking’ does not cause a spurious constraint as the error quickly vanishes with the reduction of element size for a reasonable radius of curvature conforming with shallow shell theory.
    Additional Material: 6 Ill.
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  • 22
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 321-322 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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  • 23
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 323-341 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The rate of convergence of the finite element method is a function of the strategy by which the number of degrees-of-freedom are increased. Alternative stragegies are examined in the light of recent theoretical results and computational experience.
    Additional Material: 15 Ill.
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  • 24
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 381-396 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Upwind finite element schemes remove spurious oscillations that occur in the solution of diffusion convection equations. Up to now these schemes lose part of their accuracy when the Peclet is large. As an improvement, it is proposed to move the integration nodes along the ‘streamlines’ before evaluating the elementary convection matrices. The displacements of the nodes along the streamlines, which are one-dimensional manifolds, are calculated analogously to well-known one-dimensional formulae. The last section of this paper illustrates this new method with the help of four examples which show its validity.
    Additional Material: 10 Ill.
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  • 25
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 314-320 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Quarter-point elements are used very frequently for fracture mechanics computations, because the quarter-point technique yields the required singular interpolation without any modification to existing software. This advantage is particularly significant for three-dimensional stress intensity factor computations because of the difficulty of implementing other techniques. However, in practical 3-D applications, the crack front is usually curved, and this note proves that a crack front distortion leads to a negative Jacobian in the region surrounding the crack front. The numerical difficulties to be expected depend on the aspect ratio of the elements.
    Additional Material: 4 Ill.
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  • 26
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 343-350 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The paper presents a smoothing technique to the oscillated contact pressure obtained by penalty methods for a class of unilateral contact problems in linear elasticity. The main result is to show that the smoothed contact pressure satisfies the so-called Babuska-Brezzi condition which dominates the convergence of the penalty method. One numerical example is described.
    Additional Material: 4 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 435-444 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A method for the exploitation of screw translation symmetry for the vibration analysis of structures is presented. The method is capable of providing significant computational economies over the use of the lower axial translational symmetry of such structures.
    Additional Material: 4 Ill.
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  • 28
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    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 629-630 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
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  • 29
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 632-634 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 661-673 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Optimal structural desingn generally deals with frame or shell structures where the optimization is limited to resizing of structural members to obtain optimum cross-sections or thicknesses. Shape optimization solves another class of problems involving continuous structural components where the optimum shape (the shape of the boundaries and the surfaces of the components) is determined. This report describes shape optimization of three-dimensional structural components. The finite element method of analysis is used employing the 20-noded isoparametric element. The objective function, mass, is minimized by the direct use of nonlinear mathematical programming, specifically the feasible direction method. Numerical shape representation and the selection of design variables are the most important aspects of the problem. The problem is addressed from a practical standpoint and techniques are presented to minimize the number of desingn variables. Isoparametric representation of the surfaces and the numerical superposition of shapes are discussed. These techniques are compared and demonstrated on simple cantilever beams and their minimum mass designs are obtained. In one example, the optimum shape of a non-uniform cross-sectinal beam is obtained under stress constraint. The final design has a crosssectional shape varying over the length of the beam which could not be predicted using the bending theory of beams. One major difficulty encountered in some problems was that the shape changes during the optimization process may require a change in the finite element mesh because the initial configuration of the finite element mesh may result in very distorted elements for the new shape. The analyis with a mesh containing distorted elements may not be possible at all or the results of the analysis may be inaccurate.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 727-735 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Vector functions having a constant or zero divergence over a quadrilateral domain are derived using a parametric co-ordinate formulation. Expansion functions with a constant curl, defined over parallelograms and triangles, which can be used in moments-based investigations of electromagnetic wave interactions with surfaces and apertures, are then obtained. Finally, two basis functions, which have appeared in the literature and have been used to solve field problems associated with rectangular apertures and arbitrary surfaces, are identified as special cases of these expansion functions.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 927-944 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Finite element formulation for stress analysis of a twisting beam is developed. The formulation is effective for a prismatic beam with solid section as well as a thin-walled beam, and can be applied both to a pure-torsion problem and a warping-torsion problem. The formulation is of a great advantage to an elastic-plastic torsion problem. The formulation does not stand on the assumption of a thin-walled structure, and therefore torsional rigidity of the section can be evaluated exactly without using the so-called Saint-Venant's torsional constant. Torsional rigidity is, in this paper, evaluated directly by a warping function of the section. Warping function is evaluated numerically due to shape of the section, due to progress of plastic region and due to effect of finite displacement (finite rotation, small strain). Pure-torsion and warping-torsion of a rectangular beam and an H-beam, which have an elastic-plastic material property, are analysed, and the extension to the finite displacement problem is discussed. Many numerical examples are provided in order to check the accuracy of the formulation.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 955-957 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 967-979 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A simple, efficient and economical numerical technique for the analysis of shallow shells-of arbitrary shape is presented. The technique is based upon the method of constant-deflection contours combined with the well-known finite element method. In the proposed method the elemental stiffness matrix is derived from a system of two consistent partial differential equations for two scalar functions using Galerkin's method. Several representative examples are included to indicate the effectiveness of the method.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 997-1017 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An equation solver for the large unsymmetric systems of linear equations arising in the application of the boundary integral equation method to problems of linear elasticity in homogeneous or piecewise homogeneous solids is presented. The solver uses Gaussian elimination. The advantages of the solver over many existing eliminational or iterational methods are that it ignores many of the large groups of zeros that occur in piecewise homogeneous work, and also restrains growth of the number of non-zero matrix entries. Memory requirements and computation times therefore are reduced for many piecewise homogeneous problems.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1055-1061 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Methods are described for forming element matrices for a wide variety of operators on tetrahedral finite elements, in a manner similar to that previously employed for line segments and triangles. This technique models the differentiation and product-embedding operators as rectangular matrices, and produces finite element matrices by replacing all required analytic operations by their finite matrix analogues. The method is illustrated by deriving the conventional matrix representation for Laplace's equation. Computer programs are available, which generate universal finite element matrices for use in various applications.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1101-1103 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Ingraffea and Manu1 and Lynn and Ingraffea2 have shown that the size of the quarter-point elements can affect the computed elastic stress intensity factor. The nature of the effect is such that, all other details remaining constant, there is a particular crack tip element size which minimizes the error in the computed stress intensity factor. Here, size of element means the radial edge length. The reasons for this size dependence are discussed below. It will be seen that the discussion is in terms of the need to simultaneously represent the singular and finite stress terms in a given problem. The discussion has relevance to other formulations of crack tip elements.
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  • 38
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1115-1130 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: In a previous paper it has been proved by the author that the integral equations arising from the application of Green's formula to the Helmholtz equation in a limited domain can show a certain type of numerical instability, if a real Green's function is used. It has been also proved that such instabilities cannot arise if a complex Green's function is employed.However, it has been found in this latter case also that numerical instabilities can occur. This has been proved and thoroughly analysed for a circular domain, and a technique of avoiding these instabilities has been devised.Furthermore, when this technique is followed, very accurate results can be obtained, regardless of wavenumber used. Thus, only three or four segments are sufficient to describe a wavelength, contrary to what until now has been obtained, i.e. that at least six segments are always necessary. This last result has been shown to be valid also for geometries other than the circular one.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1145-1151 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1699-1717 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Dependence of dynamic response of nonlinear mechanical systems on design variables is analysed. An adjoint variable method is used to derive first- and second-order derivatives of measures of dynamic response with respect to design variables. A computational algorithm is presented for numerical calculation of first and second design derivatives. A simple oscillator example is solved analytically and by the adjoint variable method, with identical results. A burst fire automatic weapon mechanism with linear and nonlinear damping is treated numerically. It is shown that quadratic appriximations of dynamic response, using results of second-order design sensitivity analysis, can be substantially better than conventional linear approximations.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1739-1739 
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    Keywords: Engineering ; Engineering General
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    International Journal for Numerical Methods in Engineering 18 (1982) 
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1745-1764 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Problems involving the diffusion and transport (angular dependence considered) of neutron radiation are frequently encountered in radiation physics and nuclear engineering. Neutron diffusion problems require substantial computer storage arising from the energy and spatial dependence, while in the case of transport problems the angular dependence of the neutron flux and of the neutron scattering process gives rise to a further considerable increase in storage. In the present work, a method has been developed which greatly eases the bandwidth problem in the solution of large systems of linear equations and algorithms have been developed to assemble and solve such systems of equations in one and two dimensions. The formalism used is the variational method and, for simplicity, linear interpolating functions have been used to derive a symmetric banded system of equations. Finite element algorithms have been implemented in the codes FEED1 and FEED2, which treat one and two space dimensions, respectively. Three benchmark problems are analysed in this paper and results are compared with finite difference discrete ordinate method solutions. It is shown that the finite element method provides fast and accurate solutions to neutron diffusion and transport problems.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1829-1854 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A general and systematic discussion on the use of the operational method of Laplace transform for numerically solving complex time-dependent linear problems is presented. Application of Laplace transform with respect to time on the governing differential equations as well as the boundary and initial conditions of the problem reduces it to one independent of time, which is solved in the transform domain by any convenient numerical technique, such as the finite element method, the finite difference method or the boundary integral equation method. Finally, the time domain solution is obtained by a numerical inversion of the transformed solution. Eight existing methods of numerical inversion of the Laplace transform are systematically discussed with respect to their use, range of applicability, accuracy and computational efficiency on the basis of some framework vibration problems. Other applications of the Laplace transform method in conjunction with the finite element method or the boundary integral equation method in the areas of earthquake dynamic response of frameworks, thermaliy induced beam vibrations, forced vibrations of cylindrical shells, dynamic stress concentrations around holes in plates and viscoelastic stress analysis are also briefly described to demonstrate the generality and advantages of the method against other known methods.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 11-29 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The dispersive properties of finite element semidiscretizations of the two-dimensional wave equation are examined. Both bilinear quadrilateral elements and linear triangular elements are considered with diagonal and nondiagonal mass matrices in uniform meshes. It is shown that mass diagonalization and underintegration of the stiffness matrix of the quadrilateral element markedly increases dispersive errors. The dispersive properties of triangular meshes depends on the mesh layout; certain layouts introduce optical modes which amplify numerically induced oscillations and dispersive errors. Compared to the five-point Laplacian finite difference operator, rectangular finite element semidiscretizations with consistent mass matrices provide superior fidelity regardless of the wave direction.
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  • 46
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 89-98 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Masters are defined as the degrees-of-freedom that are retained in the reduced eigenvalue problem. Various qualitative guidelines to select masters are published in the literature, but it is difficult to apply them to complex structures. In this paper a computational algorithm to select masters for complex structures is presented. This algorithm is based on a guideline14 which assures that the associated Guyan reduction process is valid. This algorithm eliminates one degree-of-freedom at a time satisfying the guideline, and preserves lower frequencies in the reduced eigenvalue problem. The algorithm presented in this paper is used to select masters for four different structural models. The natural frequencies of the associated reduced eigenvalue problems are calculated and compared with those calculated from the full eigenvalue problems.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 135-149 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite element model for symmetrically loaded shells of revolution is described. The nonlinear geometric effects are accounted for by incrementing loads and iterating for equilibrium. The iteration process also allows for nonlinear materials. The shell model accounts for large strains, large rotations and shear deformation. Three example problems demonstrate the ability of this model to solve linear problems. Also, three example problems demonstrate the versatility and accuracy of this model for nonlinear problems. These nonlinear example problems are an axially loaded cylinder and an internally pressurized spherical shell that have large membrane strains, and a cylinder that deforms into a spherical shape, having large rotations.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 166-166 
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  • 49
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 167-180 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The paper outlines a numerical procedure for the finite element solution of convective diffusion problems with significant convective terms using conventional (not upwinded) Galerkin methods in connection with ‘boundary-layer type’ elements. The underlying argument in the sequel is that the poor stability properties of conventional Galerkin methods are caused by the insufficient approximation of eigensolutions. These are located at some sections of the boundary and are only present within a generally very thin layer. Consequently, the identification of these layers and the satisfactory approximation of the eigensolutions are necessary and totally sufficient for a satisfactory solution. In the following we intend to present this procedure, its theoretical background and selected numerical results.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 245-257 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The solution of elastostatic bodies in frictionless contact is obtained by an automated direct method which exploits the theory of linear elasticity and circumvents the need for the inclusion of artificial interface elements, mathematical programming techniques or computation of contact pressure. The method is simple and economical to use and can be easily appended to existing numerical schemes such as the finite element method. The formulation and numerical algorithm are presented for body combinations which are independent of relative tangential displacements along the contact surface. The method is illustrated through an elementary example amenable to hand calculation. Numerical results for more realistic problems are given and compared to known solutions. It is concluded that the method provides a powerful means for both the analysis and design of contacting bodies when used in conjunction with a finite element computer program.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 291-309 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite element stress analysis capability for plane elasticity problems, employing the principle of stationary complementary energy, is developed. Two models are investigated. The first is a 24 d.o.f. rectangular finite element. The second model consists of an 18 d.o.f. triangular element. In order to allow for self-equilibrating stresses which are continuous within the element, the well-known Airy stress function ø is used. The function ø is represented by means of quintic Hermitian polynomials within the finite element. The values of the ø function and its derivatives up to order two are used as nodal parameters. For matching the stress function with the prescribed boundary tractions, additional equations are developed considering the force and moment equilibrium equations on the boundary consistent with the assumed stress function. These additional boundary equations are incorporated into the system equations using the Lagrangian multiplier technique. Excellent results are obtained for linear elastic problems even with coarse finite element discretization. Some examples of plane elasticity problems are solved and results compared.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 363-380 
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    Notes: The problem related to the derivation of conforming deep shell finite elements is examined in the light of the thin shell theory and using the classical Loves strain energy formulation. A family of quadrangular finite elements allowing for variable curvature is developed. It is shown how an exact conformity of the displacements can be ensured in a large number of cases.Various static and dynamic applications are used to illustrate the advantages of these elements.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 397-419 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The development of a geodesic beam finite element for use with a specific circular cylindrical shell finite element in the analysis of reinforced circular cylinders is described.The basic strain and curvature change equations are given and, from these, three versions of the geodesic beam element are developed. Two of the beams have nodal degress-of-freedom identical with the shell element. They differ in the treatment of the terms relating to rotation about the principal normal. The first version ignores this parameter but, under certain circumstances, the stiffness matrix contains terms which can contribute to the strain energy under arbitrary rigid body movement of the beam. This deficiency is removed by applying an aspect of Koiter's theory which is used to transform the curvature change equations.The introduction of additional rotational degress-of-freedom, at the end nodes of the beam element, produces a variation which is capable of accurately representing and transmitting in-surface bending effects to an adjoining beam element.Numerical evaluation successfully compares finite element solutions to basic problems for straight, circular and helical beams with theoretical strain energy solutions. Finally the beam is used in conjunction with a shell element to analyse an infinitely long circular cylinder, reinforced with equispaced rings, subjected to internal pressure.
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    International Journal for Numerical Methods in Engineering 18 (1982) 
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 521-533 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Finite element analysis of engineering structures commonly requires the use of inter-nodal displacement constraints. Current algorithms for this facility - elimination, Lagrange multipliers and penalty function methods - are briefly reviewed. An alternative approach is proposed which avoids some of the problems of these methods. This technique uses solution of the unconstrained stiffness equation with an extended number of right-hand sides. The resulting solutions are then combined to satisfy the constraints. This method has application in the synthesis of sub-structures with incompatible boundary variables. It is particularly efficient when the constraint affects many variables but the kinematics of the constraint can be expressed in terms of few independent variables, e.g. rigid body motion of part of the structure. In common with the Lagrange method, it produces data for use in a nonlinear analysis with constraints. The formulation of ‘rigid body’ constraints in geometric nonlinearity is detailed and demonstrated.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 569-582 
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    Notes: All physical process change with time and although physicists and engineers often freeze them to simplify their model studies, this is not always possible. Add to this the existence of several subregions within the modelling domain with different physical properties, the size and number of which change with time, and one has produced what might appear to be an intractable problem. Previous studies have shown that adaptive grids are an inconvenient way of modelling such moving interface problems and suggested that the use of a fixed grid with special discontinuous elements affords an efficient solution technique.This work presents and develops the characteristic matrices for two such elements, namely a quadratic triangle with an internal interface modelled by two straight lines and a quadratic isoparametric element. Both these elements are tested against an analytical solution to a simple Poisson equation. Such tests reveal the performance of the proposed elements to be satisfactory except for the definition of gradients near the interface.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 591-607 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: To account for plastic deformation in plate and shell structures an elasto-viscoplastic solution algorithm is considered based on Perzyna's model for material behaviour. This algorithm can be employed to solve for time-dependent elasto-viscoplastic situations and by allowing steady-state conditions to be reached, elasto-plastic problems can also be considered.For the large displacement elasto-viscoplastic analysis of thin shells, an incremental stiffness procedure is employed together with a Lagrangian description of the stress and strain vectors. The Semiloof plate and shell elements are used for finite element space discretization.The procedures developed are applied to the solution of several numerical examples and the solutions compared with results from other sources where available.
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    International Journal for Numerical Methods in Engineering 18 (1982) 
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 675-685 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The position, size and surface temperature of circular holes inside a two-dimensional heat conductor are optimized to produce a minimum variation in surface temperature over a portion of the outer boundary. This problem, whic arises in thermal desing of moulds and dies, resembles those encountered in structural shape optimization because the internal geometry of the heat conductor depends on the design variables. In this paper, some of the traditional difficulties associated with shape optimization are overcome by analysing steady heat conduction with a special boundary integral method developed for two-dimensional regions with circular hole. This approach eliminates the need to regenerate a finite element mesh over the interior of the region each time the geometry is changed during the design process. It also increases the efficiency of the analysis by reducing the number of unknowns in the numerical discretization of the region. Since the objective function depends only on the boundary temperatures, there is no need to determine temperatures in the interior.The analysis method is applied to two problems arising in optimal thermal design of compression moulds. These examples show that the number of holes choson for the design strongly affects their resulting optimal arrangement as well as the ultimate uniformity of the cavity surface temperature.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 755-764 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A triangular plate bending hybrid element is constructed according to Reissner's principle. It has 9 degrees-of-freedom and the shear effect is included. The C0 formulation of thick plate is directly developed to solve the thin plate by imposing the discrete Kirchhoff constraints. The matching problem for bending and shear in the hybrid model of thick plate is effectively treated by use of the principle of the energy regulation such that the unified analysis of thick and thin plates is realized. Finally, numerical examples are presented.
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  • 62
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 798-798 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 63
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 798-798 
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  • 64
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    Notes: In this paper a triangular thin shell element is presented where C1 continuity is introduced by means of the penalty function technique. The displacement field has complete cubic polynomials for each component. The introduced constraint condition is the continuity of normal slopes of the transverse displacements along interelement boundaries. Classical thin shell theory for small deformations is applied. Several analyses of thin plates and shells are performed, including a large problem of practical interest, to study the effect of an increasing penalty factor. The accuracy of the results is estimated and compared to the actually occurred error. In the conclusions a recommended value for the penalty factor is given.
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  • 65
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 909-926 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An interactive computer graphic system has been developed for generating and editing three-dimensional finite element meshes. The various difficulties inherent to the generation of solid three-dimensional geometries through an effective use of computer graphic techniques are examined to explain the advantages of this system. The method is a combination of discrete transfinite mapping and cubic spline blending algorithms, used, respectively, to create plane cross-sectional meshes, and to generate the three-dimensional geometry by interpolaring between the cross-sections. The communication between analyst and machine is based on a digitizing tablet and a refresh vector scope. The dynamic viewing capabilities and depth cueing of the vector display greatly enhance the perception of the mesh three-dimensionality. Multi-view dynamic display is also employed to facilitate node or element selection. The flexibility and usefulness of the system are illustrated with the help of three examples of practical interest.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 954-955 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 67
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 959-966 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Presented herein are methods to generate special interpolation formulae of the following type: (i) C0 continuous interpolation over triangular elements which induces a given type of singularity for the first derivatives at one of the vertices, and yet preserves ‘rigid and constant strain’ motions, (ii) C1 continuous interpolation over triangular elements which induces a given type of singularity for second derivatives at one of the vertices.
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  • 68
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1019-1029 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An explicit algorithm which gives stable finite-difference schemes, of order of accuracy greater than two, for solving a quasi-linear hyperbolic system of partial differential equations in several space dimensions is presented. Third and fourth order accuracy schemes are derived using this algorithm. The fourth order scheme needs fewer flux evaluations than the scheme given by Abarbanel and Gottlieb.1 Numerical results obtained show that these schemes have the expected accuracy and stability.
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  • 69
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1063-1076 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Displacement formulated singular elements are compared to isoparametric quarter-node elements. The total stress and displacement solution for each element is decomposed into singular and regular components for evaluating stress intensity factors. Specific relationships between nodal displacements and the singular component of stress are presented for the isoparametric element at selected locations within the element. Numerical results for KI and KII in the slant crack problem are presented. The singular components are shown to produce superior results when considering crack opening displacements.
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  • 70
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    International Journal for Numerical Methods in Engineering 18 (1982) 
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  • 71
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1197-1211 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A compact FORTRAN subroutine for reducing unsymmetric band matrices (in-core solution) is presented. As usual, the zeros inside the band are skipped during the Gauss elimination. However, the theme of the paper is centred on a new approach in applying the above-mentioned band solver to transient problems. The approach results in considerable saving of computational time while also achieving reduction in memory space. This double advantage makes it particularly useful in handling dynamic real world problems. Extension of the use of the algorithm to moving boundary problems is indicated.
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  • 72
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1245-1248 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Simplicial finite elements have many symmetries, which are commonly exploited in programs to save computing time and storage. All possible permutations of the interpolation functions of an N-simplex can be expressed in terms of N basic permutation operations. The relevant permutation matrices are given for triangles up to order 20 and tetrahedra up to order 10.
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  • 73
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1265-1270 
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  • 74
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1297-1311 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Two new finite elements are developed for the Mindlin theory plate bending problem. The formulation is based on the modified Hellinger-Reissner principle with independent transverse shear strains. Numerical examples indicate that, with properly assumed transverse shear strains, these new elements designated as PLAT8 and PLAT8H do not exhibit locking effect even for very thin plates.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1375-1384 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Integration over triangles where the integrand contains a singularity at one of the vertices is considered in this paper. The applications for such problems arise in using the boundary element method. Low order formulae are presented and compared to previous methods where the singularity was not considered.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1401-1411 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An exact expression is derived for the potential due to a uniform source distribution over a triangular domain. This expression, which is valid for arbitrary field points, is important for the numerical solution of electromagnetic field problems. Numerical values of the potential are calculated by using the expression obtained, and are compared with the results derived by numerical integration.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1423-1423 
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1425-1427 
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  • 79
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1455-1468 
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    Notes: Hybrid stress elements are known to provide accurate results for analyses of plate bending; in particular, for the prediction of moment distribution. The construction of hybrid stiffness matrix requires numerical inversion of a moment matrix, evaluation of some relatively complicated boundary integrals and several matrix transformations. Each of these operations can be time-consuming, and the matrix inversion can result in a loss of numerical accuracy.This paper devises methods to explicitly invert the moment matrices. We find that for triangular elements the inverse is independent of the element shape and is only inversely proportional to its size. We also use a novel set of displacement variables, which greatly simplifies the boundary integration. The displacement variables are chosen in a hierarchical form so that lower order elements can be determined by straightforward reduction of excess terms in a higher order element. Except for the nodal displacements at the vertices, the present approach involves only variables at the midpoints of the sides of an element.
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  • 80
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1505-1520 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The present paper deals with the theoretical and numerical treatment of dynamic unilateral problems. The governing equations are formulated as an equivalent variational inequality expressing D' Alembert's principle in its inequality form. The discretization with respect to time and space leads to a static nonlinear programming problem which is solved by an appropriate algorithm. Some properties of dynamic unilateral problems are outlined and the influence of several parameters on the solution is investigated by means of numerical examples.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1565-1568 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The use of warping displacement functions for the torsional stiffness representation of beams with rectangular cross-sections is studied. These functions can directly be employed in the displacement-based formulation of Hermitian and isoparametric three-dimensional beam elements for linear, elastic-plastic or large displacement/large rotation analysis. the results of some studies are given to demonstrate the applicability and use of the proposed functions.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1583-1585 
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    Keywords: Engineering ; Engineering General
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1601-1611 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A closed solution for dynamic problems with the transform technique is possible for linear behaviour only. Therefore, a strategy for the solution involving nonlinear material behaviour has been developed. Herewith, an iterative equalization is made possible by the repeated transform of the differential equations given through the initial strain method.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1679-1684 
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  • 85
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1719-1732 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A two-dimensional linear elastodynamic analysis of crack initiation, fast crack propagation and crack arrest in the DCB specimen is presented. The analysis is performed using the previously developed SMF2D code in its generation mode. The experimentally measured crack tip motion, as well as the specimen's geometry and its material characteristics, serve as input to the simulation. The dynamic stress intensity factor, the dynamic energy release rate and the various distributions of energies are subsequently evaluated. The numerical results are found to be in very good agreement with analytical and experimental findings.
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  • 86
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1733-1735 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The solution of a fourth order differential equation, which governs a number of problems in structural mechanics and possibly elsewhere, is considered. It is shown how the use of complex arithmetic can be avoided in the computation.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1739-1740 
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1765-1784 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A powerful new finite boundary concept of seeking field solution, at few selected regions in the solution domain, is introduced. Also a highly economical finite boundary method (FBM) which would greatly reduce the size of the coefficient matrix of the resulting system of simultaneous algebraic equations, requiring lesser computer memory and lesser computing time, is developed. Fluid flow fields governed by the basic elliptic partial differential equations - the Laplace's and the Poisson's equations - in two independent variables are mainly considered. The computational merits of the FBM are shown by solving, as an example, a simple representative flow problem, and the relevant computational finite boundary formulae are given in tabular form. The formulae are numerically derived based on a generalized method presented here. The added feature of the FBM is that it proves to be equally economical even when the solution is sought in the entire flow domain. The problem of steady-state viscous flows governed by the Navier-Stokes equations, the system of two simultaneous partial differential equations - the Poisson's equation and the vorticity transport equation - makes the FBM doubly economical. The possibility of developing an efficient hybrid computational algorithm, for curved problem boundaries, in conjunction with the finite element method, is discussed. The extension of FBM to transient, non-elliptic problems and to three-dimensional problem fields is also indicated. The FBM has been discussed in a more detailed manner so as to clearly bring out the advantages of the new finite boundary concept.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1801-1820 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A Fourier series solution is presented for a system of first-order partial differential equations which describe the linear elastic behaviour of a thick rectangular plate resting on an elastic foundation and carrying an arbitrary transverse load. The lateral edges of the plate are unstressed. A central step in the method for solving the system of equations is to combine a complementary function with a particular solution of the system in order to satisfy the boundary conditions. The complementary function is the sum of two series. The terms of the first series are products of a Fourier term in one space variable with the solution of an eigenvalue problem in the other space variable. The second series is similar and comes from reversing the roles of the space variables.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 1855-1871 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A finite element nonlinear shell model has been developed using Reissner's symmetrically loaded shell-of-revolution theory. This model is capable of modelling nonlinear strains, large rotations and nonlinear materials. This paper discusses the limitations of this model by deriving the basic equations and describing the simplifying assumptions used in the theory and the model. Possible extensions of the model are discussed also.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 259-271 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A hybrid stress finite element procedure for the solution of bending stress intensity factors of a plate with a through-the-thickness crack is presented. Reissner's sixth-order plate theory including the effects of transverse shear deformation is used. The dominant singular crack tip stress field is embedded in the crack tip singular elements and only regular polynomial functions are assumed in the far field elements. The stress intensity factors can be calculated directly from the crack tip singular stress solution functions. The effects of the plate thickness, the ratio between the crack size and the inplane dimension of the plate, and the singular element size on the stress intensity factor solution are investigated.The effects of the explicit enforcement of traction-free conditions along crack surfaces, which are the natural boundary conditions in the present hybrid stress finite element model, are also investigated. The numerical results of bending of a plate with a straight central crack compare favourably with analytical solutions. It is also found that the explicit enforcement of traction-free conditions along crack surfaces is mandatory to obtain meaningful results for the Mode I type of bending stress intensity factor.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 477-502 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A geometrically nonlinear formulation using total Lagrangian approach is presented for the axisymmetric shell elements. The basic element is formulated using the co-ordinates of the mid-surface nodes and the mid-surface nodal point normals. An important aspect of the formulation presented here is that the restriction on the magnitude of the nodal rotations is eliminated. This is accomplished by retaining true nonlinear nodal rotation terms in the definition of the displacement field and the consistent derivation of the element properties based on this displacement field. The element properties are derived and presented in detail. Numerical examples are also presented to demonstrate the element behaviour and the accuracy.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 775-781 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 798-798 
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 801-828 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Hybrid-stress eight-node isoparametric multilayer plate elements are developed for the analysis of thin to thick fibre-reinforced composite plates. Transverse shear deformation effects are incorporated by allowing a linear through-thickness displacement variation for in-plane displacements in each layer, with displacement continuity enforced along interlayer surfaces. An alternative, kinematically constrained through-thickness displacement distribution is also studied, characterized by laminate reference plane displacements and non-normal rotations. All stress components are included and are interpolated independently within each layer; interlayer surface traction continuity and laminate upper/lower surface traction-free conditions are satisfied exactly. Alternative forms of in-plane stress distributions are examined and the best is shown to be based on a rationale used previously for single layer hybrid-stress plate elements to avoid locking in the thin plate limit. Selected example problems are used to demonstrate the convergence and effects of plate thickness for each of the elements, and limited stress results serve to verify the expected optimal sampling points.
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 879-895 
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    Notes: A transitional shell finite element which is useful for the analysis of shells of revolution with local deviations is developed. For the analysis of such a structure, rotational shell elements may be used in the axisymmetric portion of the shell, while general shell elements are needed in the region where deviations create a local non-axisymmetry. The transitional shell element connects these two different types of elements. To facilitate the transition, a line node, which can accommodate any type of shape function, is developed. Numerical examples are presented to demonstrate the accuracy of the new element.
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  • 97
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  • 98
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    International Journal for Numerical Methods in Engineering 18 (1982), S. 863-878 
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    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: A direct vector combination procedure is developed for the formulation of finite element stiffness matrices. Only the homogeneous solution modes to governing equations of a problem and a uniquely defined interpolation displacement function along the element boundary are used to generate pairs of nodal displacement and nodal force vectors. The stiffness matrix is obtained by a simple multiplication of the nodal displacement and nodal force vectors. The element formed passes all the higher order patch tests for the order of solution modes included in the formulation. However, the stiffness matrix may become unsymmetrical. Restoring symmetry leads to compromising some of the higher order patch test performances. The present procedure is shown to have direct relations to those of the displacement model and the hybrid stress model. The present procedure presents new possibilities for the improvement of element performance. The procedure itself can also be used to study the limitations of element behaviour.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 99
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 945-948 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A common cause of costly abortive computer structural analysis runs is the failure to identify and constrain linear dependencies inthe stiffness matrix, most of which results from axis transformation. This paper describes a very simple and economical method for automatic constraining the linear dependencies in structure made up of plates and beams. It can be easily installed in general-purpose finite element programs.
    Type of Medium: Electronic Resource
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  • 100
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 18 (1982), S. 954-954 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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