Elastic–plastic and viscoplastic behaviors of pore-containing solids: a computational study on periodic structures

Purpose The purpose of this paper is to systematically investigate the influence of porosity, spatial distribution of pores and strain-rate sensitivity on the elastic–plastic and viscoplastic properties of pore-containing solids. Design/methodology/approach This work uses a finite element unit-cell approach to examine the mechanical response of three periodic closed-cell porous architectures: simple cubic (SC), body-centered cubic (BCC) and face-centered cubic (FCC). Rate-independent and rate-sensitive constitutive models are applied under uniaxial loading, to evaluate the overall stress–strain behavior, effective properties and internal deformation fields. Findings Numerical results demonstrate the fact that higher porosity results in lower effective Young’s modulus, Poisson’s ratio and plastic yield strength. An increase in loading rate for the viscoplastic solid leads to an enhancement of plastic flow strength. The existence of pores leads to a decrease in overall strain-rate sensitivity. This decreasing effect is more pronounced if the strain-rate sensitivity of the solid matrix is higher. The porous materials with a lower strain-rate sensitivity of the solid matrix exhibit more concentrated plasticity around the void, compared to the higher strain-rate sensitivity counterpart. Originality/value By consistently comparing SC, BCC and FCC closed-cell structures using a unit-cell finite element framework, the study clarifies the role of pore morphology and pore concentration in governing rate-dependent strength and plastic strain localization – an aspect rarely addressed in prior studies.