COMPARISON OF 4 MODELS FOR THE COMPRESSIBILITY OF BREADS AND PLASTIC FOAMS

The sigmoid compressive stress-strain relationship of rye bread, pumpernickel bread and two polyurethane foams (0-75% deformation) were fitted by four empirical models having three or four parameters. No unique model was inherently superior for goodness of fit or for strain definition, that is whether it was presented as an engineering or Hencky's strain. Two models, however, one with three and the other with four parameters, were easier to interpret in terms of stress-strain relationship shape characteristics and are recommended.