On global volume changes accompanying certain plane-strain nonlinear elastic deformations

is shown in this paper that for certain classes of unconstrained isotropic elastic solids, predictions can be made as to whether the overall volume changes which accompany two nonlinear elastic deformations (namely the radial deformation of cylindrical tubes and the bending of rectangular blocks into annular cylindrical sectors) are expansive or contractive. It is emphasised that such predictions may be viewed as universal relations for the material classes concerned. 0 1997 Elsevier Science Ltd.