Failure by buckling mode of the pore-strut for isotropic three-dimensional reticulated porous metal foams under different compressive loads

Compression is one of the most basic loading modes for engineering materials, and the failure of lost stability is possibly resulted from buckling for the bar under compression. The pore-strut within porous metal foams under compression may be similar to the compression bar, so the strut is possible to buckle when the porous body is under compressive loads. With the analytical property model of the simplified structure, the pore-strut buckling behavior is analyzed for isotropic three-dimensional reticulated porous metal foams, and the failure modes resulting from this buckling are investigated for these materials under compressive loadings. These loading modes cover all of three loading conditions, including uniaxial compression, biaxial compression and triaxial compression. The treating ways of the pore-strut are relative to three slenderness-ratios, including three conditions of thin-long bar, middle-long bar and stocky bar. Based on these works, the mathematical relationships between nominal main stresses and porosity are found for this buckling failure of these materials under compression. Through the relevant expression, the relevant strength criterion and the relevant loading condition resulting in the strut buckling are further achieved for these porous metal foams under compression.

Research highlights
► As for isotropic three-dimensional reticulated porous metal foams with even structure, the porous body under compression will fail resulting from the elastic buckling of the pore-strut when θ⩾1-483π/πE/σp+622 where θ is the porosity, and E and σp are respectively the Young modulus and the proportional limit of the corresponding dense material species.
► For the above-mentioned porous materials, the porous body under compression will fail resulting from the elasticoplastic buckling of the pore-strut when 1-483π/πE/σp+622>θ⩾1-483π/(a-σs)/b+622 where σs is the yield stress of the corresponding dense material, and both of a and b   are material constants.
► For the above-mentioned porous materials, the porous body under compression will fail resulting from the brim yield of the pore-strut when θ<1-483π/((a-σs)/b+62)2.