The primary goal of this study is to develop a new yield function for Structural Porous Metals (SPM), which is an innovative class of material developed by McDonnel Douglas Aerospace Company. The SPM differs from conventional fully dense Ingot Metals (I/M) and partially dense Powder Metals (P/M), for the reason of having distributed closed pores and maintaining the pores after metal working which opposes the goal to densify the metal in case of P/M. Due to the structural difference the existing Yield Criteria for I/M and P/M are not applicable for SPM, and so a natural quest evolved to find a new Yield Criterion for SPM.
The yield criterion is developed by using the principle of virtual work. In this approach, all the strain energy required for deformation is accounted for. Considering the gas pressure, additional work is required to compress the gas inside the closed pores. This work term has to be added to the yield criterion. Along with yield criterion, flow rules for SPM are developed for predicting the behaviour of SPM during metal working. Experimental results on deformation processing of SPM are also discussed and compared with FEM results from a software.