A mathematical theory of plasticity for compressible P/M materials

A mathematical equation for the calculation of the yield stress in the case of the simple upsetting-compression test is proposed for P/M sintered pref orms of materials. The new yield function developed by Doraivelu and his co -workers, taking into account the hydrostatic stress, is considered for the development of the above equation. Numerical integration is carried out in order to compute the yield stress, using the above-mentioned mathematical equation. The ratio of the yield stress of the P/M porous material to the y ield stress of the fully dense material is found to increase with increase in densification due to deformation. Further, a theory for the calculation of stresses such as the hoop and hydrostatic has been developed using the p lasticity equations. (C) 1999 Published by Elsevier Science S.A. All rights reserved.