Mechanical characteristics and foam filling enhancement mechanism of polymeric periodic hybrid structures under uniaxial compression

Abstract

In this study, two types of polymeric periodic hybrid (PPH) structures with hexagonal and re-entrant cells were proposed and manufactured by 3D printing using polylactic acid (PLA). PVC foam was adopted as filler material. The mechanical characteristics of PPH structures under uniaxial compression were experimentally and numerically investigated. Experimental results show that PPH structures with foam filling in re-entrant cells exhibit higher elastic modulus and peak stress than those with foam filling in hexagonal cells, which is due to the bi-directional compression of the foam filler in re-entrant cells. Moreover, their deformation processes are more stable, benefiting from compatible deformation between hexagonal and re-entrant cells. With the increase in foam filling volume fraction, the plateau stress and specific energy absorption of PPH structures increase. Numerical results reveal that the enhancement efficiency of foam filling gets improved by suitably increasing the cell wall thickness. The fully foam-filled PPH structures exhibit significantly higher yield strength than the fully foam-filled hexagonal honeycomb structures, and also possess excellent stable deformation characteristics compared with fully foam-filled re-entrant honeycomb structures. The PPH structures proposed in this study show superior comprehensive mechanical performance, thus offering potential application prospects in structural protection fields.