The mechanical response of Rohacell foams at different length scales

The quasi-static mechanical response of polymethacrylimide (PMI) foams of density ranging from 50 to 200 kg m−3 is investigated in order to provide experimental data to inspire and validate numerical constitutive models for the response of polymer foams. The macroscopic mechanical response is characterised by conducting quasi-static compression, tension, shear and indentation experiments, whereas microscopic deformation mechanisms are identified by conducting in situ SEM observations during static compression and tension tests; it is shown that foams of low density collapse by cell wall buckling while foams of high density undergo plastic cell-wall bending. As a result, both the elastic and plastic macroscopic response of the foam display a tension/compression asymmetry.