Investigation into multiaxial mechanical behaviors of Kelvin and Octet-B polymeric closed-cell foams

As a class of effective lightweight energy absorption materials, periodic closed-cell foams have been widely applied in engineering, in which the Kelvin and Octet-B foams have demonstrated great value in the research of multiaxial mechanical characteristics. For this reason, this study aims to develop a series of realistic finite element analysis (FEA) models for investigating their uniaxial, compression-shear, and arbitrary triaxial compression performance. Under uniaxial loading conditions, the mechanical responses and deformation modes of the two foams are compared and analyzed with different densities. The influence of different loading angles is also considered under compressive-shear loading. The deformation pattern of foams subject to equal biaxial and hydrostatic loading are compared with uniaxial compression. Based on sufficient simulation data, the initial yield surfaces of the two foams are plotted in the von Mises and mean stress plane, and fitted by three theoretical yield criteria characterized in terms of quadratic functions. It is found that the Miller criterion can better describe the initial yield surface shape of Kelvin foams than the yield models of Deshpande-Fleck and Zhang et al.; while the above yielding models are all of high fitting accuracy for the Octet-B foam. Further, the ability to resist initial yield of the Kelvin foam has proven superior to Octet-B foams by calculating the curve integration. The study is anticipated to provide new insights into novel design and extensive applications of periodic closed-cell foam materials in practice.

Automated summary

This study develops a series of finite element analysis models to investigate the performance of periodic closed-cell foam materials under uniaxial, compression-shear, and arbitrary triaxial compression. The mechanical responses and deformation modes of different densities of Kelvin and Octet-B foams are compared and analyzed. The study also explores the influence of loading angles and compares the deformation patterns under equal biaxial and hydrostatic loading with uniaxial compression. The initial yield surfaces of both foams are plotted and fitted by theoretical yield criteria, with the Miller criterion providing a better description for the Kelvin foam.