Experimental tests & theoretical model for strain localization and cyclic damage of polyurethane foam cylinders in uniaxial compression

It has been observed by several authors that the deformation of polyurethane foams under uniaxial compression is not homogeneous. It has also been observed that, under cyclic deformation, a progressive stepping down of the loading curve (cyclic damage) takes place. The two phenomena can be described by coupling the model for strain-localization developed in [1], [2], with the rheological model for cyclic damage presented in [3]. In the strain-localization model, the foam is represented as a chain of non-linear elastic springs with non-convex strain energy, and the localization is interpreted as a progressive phase change. In the cyclic damage model, the foam is represented by a series of surface elements undergoing contact with recoverable adhesion