Fatigue failure of an open cell and a closed cell aluminium alloy foam

Abstract

AbstractÐThe tension±tension and compression±compression cyclic properties are measured for an open cell``Duocel'' foam of composition Al 6101±T6, and a closed cell``Alporas'' foam of composition Al± 5Ca±3Ti (wt%). The Duocel foam has a relatively uniform microstructure, and undergoes homogeneous straining in both monotonic and fatigue tests. In contrast, the Alporas foam is more irregular in microstructure, and exhibits crush-band formation at random locations under uniaxial compression; in compression±compression fatigue, a single crush band forms and broadens with additional fatigue cycles. Progressive shortening of the specimen in compression±compression fatigue, and progressive lengthening in tension±tension fatigue are due to a combination of low cycle fatigue failure and cyclic ratchetting. S±N fatigue curves are presented for the onset of progressive shortening in the compression tests, and material separation in the tension tests; it is envisaged that such curves will be of practical use in design. #

Compression fatigue of a cellular Al alloy

“…But, there are further strain jumps similar to that at N T . More uniform strain rates have been found in the less heterogeneous material [11]. By replotting dm/dN against strain, m max ( Fig.…”

“…In some cases, the present results are compared with those from another batch of the material, reported elsewhere [11], which had somewhat different characteristics, related to superior material homogeneity.…”

“…1 The consequent S/N plots ( Fig. 4a) reveal a substantial difference in fatigue between this material and another batch [11]. However, upon normalizing by | 0 , the results for both batches superpose (Fig.…”

“…These methods are used to identify the mechanisms and establish preliminary design criteria. A companion paper [11] provides further information. It examines the tension -tension as well as compression -compression cyclic properties of both open-cell and closed-cell aluminum alloy foams.…”

High strain rate compressive behaviour of aluminium alloy foams

“…The shapes of the curves are qualitatively the same as for the Alulight foam. However, the mode of deformation is di!erent for the two foams: for the Duocel foam deformation is uniform with no band formation [18,30], whereas crush bands form within the Alulight.…”