A computational study of elongated pore interactions in a low density porous copper

A finite element investigation of an array of high aspect ratio pores under tension deformation was performed to evaluate geometric features affecting bulk yield, strain hardening and strength in a ‘gasar’ porous copper material of 21.5% pore volume fraction. The analysis simulated a planar triagonal array representing a central pore and its six nearest neighbors. Typical pore dimensions of 18 μm in diameter, 108 μm in length and 60 μm transverse spacing between centers were used for the model. Local transverse constraint above and below groups of pores will vary due to the presence or absence of isolated pore free zones throughout the microstructure. Displacement boundary conditions were selected to evaluate the effect of zero, partial and full transverse constraint. The normalized load vs. normalized displacement results from the model are found to exceed that of the solid copper matrix by 89% for full transverse constraint and 16% for partial transverse constraint at peak normalized load, and 6% below that of the solid copper matrix for zero constraint at 0.20 normalized displacement. These results provide insight into the role of pore interactions and local geometric constraint on the comparatively high bulk strength observed in these materials. Full transverse constraint is also responsible for the deformation localization consistent with the appearance of the fracture surface.