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Aspects in the formulation and application of finite elements to metal forming problems

Conference ·
OSTI ID:175454
;  [1]
  1. Univ. of British Columbia, Vancouver (Canada)
In this paper, some important aspects in the application of Finite Elements (FE) to problems of large plastic strains and metal forming are investigated. Namely, we discuss the conditions of plastic incompressibility, the friction effects, combination of material and geometric nonlinearity, boundary condition updating and the need to unified general formulation. The practical applications considered are flat punch indentation and plane strain extrusion problems. For the flat punch indentation problem axisymmetric 8-node isoparametric elements together with 2-node gap elements are used. The radial displacement Ur, the second principal stress S{sub 22} and equivalent strain S{sub eq}, were calculated. It is shown that the distributions of U{sub r} and S{sub eq}, from the commercial FE programs NISA and ANSYS are similar, and the values are close to each other, but the distributions and values of S{sub 22} are quite different. In the application of metal extrusion, the problem is modeled by plane strain 8-node isoparametric elements and 2-node gap elements. The options of material nonlinearity only as opposed to combination of material and geometric nonlinearity as well as considerations of boundary condition updating were investigated and the results from the two programs are assessed. The basic shortcomings in using such commercial programs in these applications are then pointed out and the need for a different type of formulation is discussed.
OSTI ID:
175454
Report Number(s):
CONF-950686--
Country of Publication:
United States
Language:
English