Compression testing of periodic cellular sandwich cores

Periodic cellular metal (PCM) hybrid sandwich cores with 95 pct open porosity have been constructed from perforated 3003 aluminum alloy (AA3003) sheets using perforation-stretching methods. Two compressive collapse mechanisms (i.e., plastic hinging and plastic buckling) were studied using two limiting test conditions: first, where the PCM nodes were restricted only by interfacial friction (i.e., free compression) and compressive forces were resisted primarily through strut bending and plastic hinging mechanisms; and, second, where the PCM nodes were laterally confined (i.e., confined compression) and compressive forces were resisted primarily through strut-buckling mechanisms. The contribution of each collapse mechanism to the overall truss core performance was studied. The strut bending during free compression was tracked by a nodal displacement mapping (NDM) technique, while the progression of confined compression strut buckling was correlated to the truss core stress-strain profile. The present data can be used to illustrate the different strengths between strut bending (free-PCM) and strut buckling (confined-PCM) collapse mechanisms.