New examples of three-dimensional dilational materials
  Two-dimensional dilational materials, for which the only easy mode of deformation is a dilation are reviewed and connections are drawn between models previously proposed in the literature. Some models which appear to be dilational materials, but which in fact are not, are also discussed. Finally, four new examples of three-dimensional dilational materials are given. 
Graeme Walter Milton
cond-mat.mtrl-sci math-ph math.MP