Creep-rupturing of open-cell foams

A repeating element consisting of four straight and uniform-thickness cell struts in a pentagonal dodecahedron model is employed to analyze theoretically the creep-rupturing of open-cell foams. In the repeating element, the solid making up cell struts is assumed to follow power-law creep and the Monkman-Grant relationship. Consequently, the theoretical expressions for describing the steady-state creep strain rate and creep-rupturing time of open-cell foams are obtained. It is shown that the creep-rupturing of open-cell foams can also be described by the Monkman-Grant relationship. Moreover, the Monkman-Grant parameters m* and B* of open-cell foams depend on their cell structure and those of solid cell struts. The Monkman-Grant parameters determined from the existing experimental results on the creep-rupturing of open-cell aluminum alloy foams are compared to those calculated theoretically from the proposed pentagonal dodecahedron model. The difference between theoretically calculated and empirically determined B* is attributed to some pre-existing cell structural imperfections in open-cell aluminum alloy foams. (C) 2008 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.