Finite element modeling of the deformation behavior of semi-solid materials

In the current study, the deformation behavior of semi-solid materials was modeled using the von Mises yield criterion in which the semisolid material was treated as a single phase material with the incompressibility conditio n in a global sense. The flow stress of the material was modeled as a funct ion of strain in consideration of the solid fraction and the breakage ratio of dendritic structure. An algorithm based on mixture theory and D'Arcy's law was developed to update the solid fraction, the distribution of which v aries within the material due to relative velocity between the solid and li quid phases during deformation. The parameters involved with the proposed m odel were determined through a parametric study in which numerous finite el ement analysis results were compared with the data from existing isothermal upsetting experiments for semi-solid Sn-15%Pb alloy. Comparison with exper imental results showed that the current approach is improved compared to pr evious compressible approaches. The generality of the current approach was examined through rigid-thermoviscoplastic finite element analyses of the se mi-solid forging of a ball-joint case under various preheating temperatures in consideration of the release of latent heat. The simulation results agr eed well with the trend of the experimental findings but showed some quanti tative errors. (C) 2001 Elsevier Science B.V. All rights reserved.