Creep-buckling of open-cell foams

A repeating element composed of four cell struts in a pentagonal dodecahedron model is used to analyze the creep-buckling of open-cell foams. The solid making up the cell struts is assumed to follow power-law creep. As a result, the theoretical expression for describing the failure time for the onset of creep-buckling of open-cell foams under uniaxial compression is obtained. Theoretical results indicate that the creep-buckling of open-cell foams depends on their relative density and microstructural imperfection and the creep parameters of solid cell struts. Furthermore, a simple relationship between creep strain rate and failure time is proposed for the creep-buckling of open-cell foams and then compared to the existing experimental results; they agree well. In addition, cell-strut creep-buckling is the dominant failure mechanism when the imposed compressive stress is close to the elastic buckling strength of open-cell foams. However, cell-strut creep-rupturing is more likely to occur when the imposed compressive stress becomes smaller. Moreover, the transition of failure mechanism from cell-strut creep-buckling to cell-strut creep-rupturing is discussed.