Large Plastic Deformations Fundamental Aspects And Applications To Metal Forming

This volume covers topics involving large plastic deformation of metallic materials. These proceedings offer an overview of the synergism achieved by combining microstructural characterization and understanding, mechanical modelling and experiments, numerical analysis and computation.

Briefly reviews the basic principles of metal forming but major emphasis is on the latest developments in the design of metal-forming operations and tooling. Discusses the position of metal forming in manufacturing and considers a metal-forming process as a system consisting of several interacting variables. Includes an overall review and classification of all metal-forming processes. The fundamentals of plastic deformation - metal flow, flow stress of metals and yield criteria - are discussed, as are significant practical variables of metal- forming processes such as friction, temperatures and forming machines and their characteristics. Examines approximate methods of analyzing simple forming operations, then looks at massive forming processes such as closed-die forging, hot extrusion, cold forging/ extrusion, rolling and drawing (discussion includes the prediction of stresses and load in each process and applications of computer-aided techniques). Recent developments in metal-forming technology, including CAD/CAM for die design and manufacture, are discussed, and a review of the latest trends in metal flow analysis and simulations.

Proceedings of the IUTAM Symposium held in Bochum, Germany, 25-29 August 1997

The IUTAM-Symposium on "Finite Inelastic Deformations - Theory and Applications" took place from August 19 to 23, 1991, at the University of Hannover, Germany, with 75 participants from 14 countries. Scope of the symposium was a fundamental treatment of new developments in plasticity and visco-plasticity at finite strains. This covered the phenomenological material theory based on continuum mechanics as well as the treatment of microstructural phenomena detected by precise experimental datas. In a restricted number, lectures on new experi mental facilities for measuring finite strains were also implemented into the symposium. Another important topic of the symposium was the treatment of reliable and effective computational methods for solving engineering problems with finite inelastic strains. Wi thin this context it was an essential feature that theory, numerical and computational analysis were be seen in an integrated way. In total 9 sessions with 37 lectures, many of them given by well known keynote-lecturers, and a poster session with 10 contributions met fully our expectations of a high ranking up-to-date forum for the interaction of four topics, namely the physical and mathematical modelling of finite strain inelastic deformations including localizations and damage as well as the achievements in the numerical analysis and implementation and the solution of complicated engineering systems. Special and important features were reliable material datas from macroscopic and microscopic tests as well as test results of complex engineering problems, like deep drawing and extrusion.

This highly acclaimed series provides survey articles on the present state and future direction of research in important branches of applied mechanics

The classical, phenomenological theory of plastically anisotropic materials has passed a long way: from the work of von Mises presented in 1928, and the HilI formulation given in 1948, to the latest papers on large elastic-plastic deformations of anisotropic metal sheets. A characteristic feature of this approach is a linear flow rule and a quadratic yield criterion. Mathematical simplicity of the theory is a reason of its numerous applications to the analysis of engineering structures during the onset of plastic deformations. However, such an approach is not sufficient for description of the metal forming processes, when a metal element undergoes very large plastic strains. If we take an initially isotropic piece of metal, it becomes plastically anisotropic during the forming process, and the induced anisotropy progressively increases. This fact strongly determines directions of plastic flow, and it leads to an unexpected strain localization in sheet elements. To explain the above, it is necessary to take into account a polycrystalline structure of the metal, plastic slips on slip systems of grains, crystallographic lattice rotations, and at last, a formation of textures and their evolution during the whole deformation process. In short, it is necessary to introduce the plasticity of crystals and polycrystals. The polycrystal analysis shows that, when the advanced plastic strains take place, some privileged crystallographic directions, called a crystallographic texture, occur in the material. The texture formation and evolution are a primary reason for the induced plastic anisotropy in pure metals.