THE EFFECT OF THE RHEOLOGICAL BEHAVIOR AND THE TRIBOLOGICAL PARAMETERON SHEET-METAL FORMING USING A NEW MODEL FOR ORTHOTROPIC PLASTICITY

Tribological parameters in metal forming have been shown to be very re levant. It is shown here that the rheological behavior using a new des cription of orthotropic plasticity can also strongly affect the result s obtained in final product. Following a review of the constitutive mo del, the implicit time-integration scheme is derived. This time-integr ation procedure is shown to be a generalization of the well-known 'rad ial-return' algorithm used for the rate -independent plasticity. Imple mentation of the new implicit procedure as a 'User Material' or 'UMAT' in the finite element program ABAQUS is then discussed. Simulation of a forming simple test by a hemispherical punch has been performed. (C ) 1998 Published by Elsevier Science S.A. All rights reserved.