Piezomorphic materials

The development of stress-induced morphing materials called piezomorphic materials is reported. The preparation of a piezomorphic material is achieved by introducing spatial dependency into the compliance matrix describing the elastic response of a material capable of undergoing large strain deformation. In other words, it is necessary to produce an elastic-gradient material. This is achieved through modification of the microstructure of the compliant material to display gradient topology. Examples of polymeric (PU) foam and microporous polymer (ex-PTFE) piezomorphic materials are presented. These materials open up new morphing applications where dramatic shape changes can be triggered by mechanical stress. A new class of materials, called piezomorphic materials, displaying stress-induced shape change (morphing) behaviour due to gradient microstructure and elastic properties is reported, and potential applications across a wide range of disciplines are suggested. The figure shows the gradient topology of a piezomorphic polyurethane foam.