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In this paper, a three-dimensional elasto-thermoviscoplastic finite element method using tetrahedral MINI-element is established. We extend the related theories from the three-dimensional rigid-thermoviscoplastic finite element method based on the tetrahedral MINI-element to the three-dimensional elasto-thermoviscoplastic finite element method. Some details about the related theories and numerical schemes are introduced with typical application examples including a homogeneous compress of solid cylinder and an automatic five-stage cold forging process of automobile part of yoke. The former showed its validity and the latter exhibited its applicability. [ABSTRACT FROM AUTHOR]

In this paper, elastic, rigid-viscoplastic and elastoplastic finite element analyses of typical metal forming processes or structural problems of multi-body cases occurring in metal forming are conducted to present their mechanical characteristics together with validation of the numerical approaches. Theoretical backgrounds are briefly introduced with an emphasis on the contact condition treatment of moving or deformable bodies. The application problems in metal forming are classified into three categories namely typical multi-deformable body case, mechanically coupled case between material and dies and bonded material group case. Mechanics of overloaded ball bearing problem, typical assembling processes, coupled material and dies problem, bolt-and-nut assembling process, composite material forming, and structural analysis problem of assembled die are solved. The predictions are discussed to validate their accuracy and to extract valuable engineering insights. [ABSTRACT FROM AUTHOR]

Liquid phase sintering is used for net-shape fabrication of high performance materials. This work reviews microstructure evolution models needed to simulate the densification and distortion events observed with the semisolid powder-liquid mixtures during sintering. Critical insight in required from the capillarity, pore collapse, solid-liquid morphology, solid phase connectivity, grain growth, and system rheology. These complications are handled using a modified time-dependent viscous flow model that requires data on grain size, density, and boundary conditions (such as substrate friction) versus time. The rheological response model coupled with finite element analysis has proven most effective in predicting final size and shape of engineering components. A simplified material parameter extraction scheme is used to determine many the material constants, providing hope for a generic model in the future. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]