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  • 1
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The aim of this study is to evaluate treatment effects of novel GBR membranes (PDLLAmembranes) applied to bony defects around dental implants on new bone regeneration alone or incombination with bioceramic bone graft (BIO-OSS®) on the mongrel dog model in comparisonwith collagen membrane (BIO-GIDE®) and therefore to assess the clinical values of the novel GBRmembranes and bioceramic bone graft material in dental implantology. 6 implants were placed inbilateral mandibular of each mongrel dog after preparation of mid- crestal defects. The defects onone side were covered with PDLLA membranes alone or with bone graft, while the contra-lateralsides received collagen membranes alone or with bone graft. These animals were sacrificed at 2, 4,8,12 weeks post the GBR-operation. And gross sample examination, standardized radiographs,99mTc-MDP SPECT and histomorphometric analysis were taken. All examinations showed similaramounts of newly formed bone beneath both types of barriers. The PDLLA or collagen membranewith bone graft groups showed better results than the membrane used alone groups. The resultsindicated that PDLLA membranes especially with bioceramic bone graft presented an improvedresponse in dealing with bony defects around implants
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Engineering computations 16 (1999), S. 347-373 
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: Two kinds of time integration methods; the dynamic explicit method and the static implicit method, have been compared, especially with emphasis on the shell formulations and the stress integration methods. Two methods have been applied to the benchmark problem named the S-rail stamping process, provided by NUMISHEET'96 committee, in order to compare their numerical results with each other and with the average values of the experiments as well. Based on the comparisons, it is shown that both time integration methods can be successfully applied to industrial sheet metal stamping simulations. In detail, the static implicit method is advantageous over the dynamic explicit method in terms of accuracy, while the latter is known to be more efficient than the former in terms of computation efficiency.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Engineering computations 21 (2004), S. 470-487 
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: The incremental radial forging process employs several tens or hundreds of incremental local strokes, so that the entire process is difficult to analyze due to large computation time and large computer memory. The objective of this work is to propose a new numerical scheme of the finite element method, automatic expansion of domain (AED), to reduce computation time and computer memory. In the AED scheme, an effective analysis domain in each local forging step is defined and then the domain is automatically expanded in accordance with the repeated process. In order to verify the validity of the criterion for the AED scheme and the applicability of the AED scheme, two-dimensional incremental plane-strain forging process is first analyzed using the proposed scheme with various criteria and full domain. In addition, three-dimensional incremental radial forging process is analyzed to verify the applicability of the proposed scheme to a practical incremental forging process.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physica C: Superconductivity and its applications 185-189 (1991), S. 2107-2108 
    ISSN: 0921-4534
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: The present work is concerned with three-dimensional finite element analysis of the hollow section extrusion process using a porthole die. The effects of related design parameters are discussed through the finite element simulation for extrusion of a triply-connected rectangular tubular section. For economic computation, mismatching refinement, an efficient domain decomposition method with different mesh density for each subdomain is implemented. In order to obtain the uniform flow at the outlet, design parameters such as the hole size and the hole position are investigated and compared through the numerical analysis. Comparing the velocity distribution with that of the original design, it is concluded that the design modification enables more uniform flow characteristics. The analysis results are then successfully reflected on the industrial porthole die design.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Chemical Physics Letters 216 (1993), S. 551-558 
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Engineering computations 14 (1997), S. 926-948 
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: Applies an updated Lagrangian finite element analysis with automatic remeshing scheme to three-dimensional hot extrusion through landless square dies. The remeshing procedure is composed mainly with decision for remeshing, transfer of state variables and mesh generation. The procedure is carried out fully automatically. In the procedure, it is difficult to generate the mesh automatically, considering the physical characteristics. Accomplishes mesh generation by introducing the modular concept. The mesh generated by the modular concept has advantages, especially for three-dimensional problems, such as economic computational time and consideration of physical characteristics. Classes the profiles of orifice into two cases; and develops the orifice adaptive module for each case and then carries out numerical examples by using the orifice adaptive modules.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Engineering computations 14 (1997), S. 901-925 
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: Describes simulations of impact forging processes. Uses the explicit time integration finite element method, which is based on direct time integration of equation of motion, to compute the deformation of the workpiece and the dies. Uses the program developed to simulate the copper blow test performed on a 350,000J counter-blow hammer. The calculated result reveals a good agreement in the final deformed configurations between the experiment and the explicit simulation. In order to compare this with the explicit method, the implicit time integration rigid-plastic finite element program considering the inertia effect is also applied to the copper blow test simulation. As a result of the copper blow test simulation using the explicit program and the implicit program, finds that the calculated results have good agreements in available plastic deformation energy, forging load and equivalent plastic strain distribution. Finally, applies the developed program to simulations of multi-blow forging processes. Presents three major findings from the multi-blow forging simulations: (1) the continuous analysis technique used for the multi-blow forging simulations works well; (2) the blow efficiency and the forging load generated by blow operations can be analysed efficiently and simulated results coincide with previous experimental and analytical ones; (3) the geometrical configuration of the workpiece is closely related to blow efficiency.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Engineering computations 20 (2003), S. 6-39 
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: The initiation and growth of wrinkles are influenced by many factors such as stress ratios, the mechanical properties of the sheet material, the geometry of the workpiece, contact condition, etc. It is difficult to analyze wrinkling initiation and growth while considering all the factors because the effects of the factors are very complex and studies of wrinkling behavior may show a wide scattering of data even for small deviations in factors. The finite element analyses of wrinkling initiation and growth in sheet metal forming process provide detailed information about the wrinkling behavior of sheet metal. The direct analysis of wrinkling initiation and growth, however, brings about a little difficulty in complex industrial problems because it requires large memory size and long computation time. From the industrial viewpoint of tooling design, therefore, readily available information on the possibility and location of wrinkling is sometimes more preferable to detailed and time-consuming analysis results. In the present study, in order to give such readily available information on wrinkling initiation, the wrinkling factor, which shows the locations and relative possibility of wrinkling initiation, is proposed as a convenient tool of relative wrinkling estimation based on the energy criterion. The reliability of the wrinkling factor is verified through the buckling analyses of sheet strips. The location and relative possibility of wrinkling initiation are predicted by calculating the wrinkling factor in various sheet metal forming processes such as cylindrical cup deep drawing, spherical cup deep drawing, and elliptical cup deep drawing. Finally, the wrinkling factor proposed in the present study is also implemented in the prediction of wrinkling in the door inner stamping process. For verification of the calculated wrinkling factor, detailed zone analyses with fine meshes are carried out for the regions where wrinkling is predicted.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Engineering computations 22 (2005), S. 165-185 
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: Purpose - In the finite element analysis of a hot forging process with hexahedral elements, flash region is difficult to analyze because of the thin shape. In this paper, a hot forging process is effectively analyzed by constructing a locally fine mesh in the flash region. Design/methodology/approach - When remeshing is decided by an error estimation and flash is generated, the boundary patch of the mesh is constructed and expanded in the normal direction of the flash region. After hexahedral mesh is constructed in the expanded patch with master grid approach, the boundary patch is compressed to the original shape and the nodes in the boundary are moved to the relative position of the boundary patch. Then, a locally fine mesh is constructed in the flash region. The quality of mesh on the boundary is again improved by adding surface element layer. Therefore, the hot forging process can be effectively analyzed by constructing the adaptive hexahedral mesh in the flash region. Findings - The results show that the locally fine mesh can be constructed in the hexahedral mesh generation procedure by constructing mesh in the expanded patch and compressing the mesh according to the original boundary patch without affecting the compatibility of element. Then, it is applied to the analysis of a hot forging process and it has been shown that the analysis result of the proposed technique can save the analysis time remarkably relative to that of the fine mesh, while maintaining the analysis accuracy of the fine mesh. Originality/value - In the finite element analysis of a hot forging process, the flash region is very difficult to analyze because it is difficult to construct locally fine mesh with hexahedral elements. A new adaptive mesh generation technique using hexahedral elements is suggested to overcome such difficulty and applied to the analysis of a hot forging process.
    Type of Medium: Electronic Resource
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