Yield criteria for porous ductile sheet metals with planar anisotropy under plane stress conditions

Modified yield criteria for porous ductile sheet metals with planar anisotropic matrices are investigated by a finite element analysis. A sheet model with a centric through-thickness hole is adopted for an analysis model. A new proposed plane stress yield function accounting for rounded vertices of a yield surface, in particular, near the uniaxial and equal biaxial loading directions based on experiments is employed for the matrix surrounding the hole. Strain hardening behavior of the matrix is considered in the present study. Two different definitions of the macroscopic yield stress are implemented here. Macroscopic yield loci and macroscopic stress–strain relationships under plane stress conditions based on the finite element computational results and those based on the modified anisotropic yield criteria are then compared and found to be in reasonable agreement.