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Radial deformations of an infinite medium surrounding a traction-free spherical cavity are considered. The body is composed of an isotropic, incompressible elastic material and is subjected to a uniform pressure at infinity. The possibility of void collapse (i.e. the void radius becoming zero at a finite value of the applied stress) is examined. This does not occur in all materials. The class of materials that do exhibit this phenomenon is determined, and for such materials, an explicit expression for the value of the applied pressure at which collapse occurs is derived. The stability of the deformation and the influence of a finite outer radius are also considered. The results are illustrated for a particular class of power-law materials. In certain respects, the present results for void collapse are complementary to Ball (1982)'s results for cavitation in an incompressible elastic material.Some brief observations on void collapse in compressible materials are made. The collapse of a void under non-symmetric conditions is also discussed by utilizing a solution obtained by Varley and Cumberbatch (1977, 1980).

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A study is given of the deformations of an incompressible body composed of a neo-Hookean material subjected to a uniform, spherically symmetric, tensile dead load. It is based on the energy minimization method using a constructed kinematically admissible deformation field. It brings together the pure homogeneous asymmetric deformations explored by Rivlin (1948, 1974) and the spherically symmetric cavitated deformations analyzed by Ball (1982) in one setting, and, in addition, Hallows nonsymmetric cavitated deformations to compete for a minimum. Many solutions are found and their stabilities examined; especially, the stabilities of the aforementioned asymmetric and cavitated solutions are reassessed in this work, which shows that a cavitated deformation which is stable against the virtual displacements in the spherical form may lose its stability against a wider class of virtual displacements involving nonspherical forms.