Degradation of elastic modulus of progressively crushable foams in uniaxial compression

The degradation of apparent modulus in progressively crushable foams in uniaxial compression is studied in this article based on an analysis of the measurement of engineering strain. It shows that the deformation mechanism of the progressive collapse of the foam causes the non-uniform deformation in the foam during uniaxial compression, which leads to the decrease of apparent elastic modulus with the increase of strain in the plateau stress regime. Theoretical predictions are compared with experimental results for different closed-cell polymeric foams with satisfactory agreement. It is also shown that this method is not applicable to the in-plane compression of honeycombs and the numerical modeling based on macroscopic constitutive equation is incapable of predicting the degradation of apparent modulus in progressively crushable foams.