2004 Volume 45 Issue 6 Pages 1829-1832
To predict the forming limit diagram of porous metals, we use the elasto-plastic finite element method in conjunction with a critical relative density criterion to simulate the deformation behavior in the upsetting of porous metallic specimens. We predict the strain instability of porous cylindrical specimens by calculating the strain paths during deformation. Strain instability is the point where axial strain starts to increase in compression. By using strain instability as a ductile fracture criterion of porous metals, we calculate a forming limit that agrees well with the experimental forming limit. The calculated relative density in crack initiation is higher than the critical relative density.