The yield behaviour of two densities of a ductile PVC foam manufactured by
Divinycell have been investigated for a range of axisymmetric compressive a
nd tensile stress states. The yield surface is found to be described adequa
tely by the inner envelope of a quadratic function of mean stress and effec
tive stress and a maximum compressive principal stress criterion. Under ten
sile loadings the deformation of these foams is governed by cell wall bendi
ng, and the uniaxial and hydrostatic tensile strengths have comparable magn
itudes. Under compressive loadings the foams deform by elastic buckling of
the cell walls, and the uniaxial and hydrostatic compressive strengths are
again nearly equal. (C) 2001 Acta Materialia Inc. Published by Elsevier Sci
ence Ltd. All rights reserved.