THE EFFECT OF SWELLING ON THE FAILURE MODE OF MATTER

A study was undertaken of the mode of failure of open- or closed-cell cellular materials depending on the variation of the relative density of the material due to swelling or variation of its porosity. Cellular materials or foams were considered as transversely isotropic, an assu mption which corresponds well with their mechanical behaviour. Using a tenser failure polynomial criterion, and as such the elliptic parabol oid failure criterion was considered, for the study of the mode of fai lure of closed-cell foams of different relative densities, it was esta blished that the failure behaviour of the swelled material drastically changes its failure mode by becoming a strong tension material from a strong compression one. Furthermore, there is a critical value of the relative density for each material, where the substance passes throug h a quasi-isotropic state and the foam behaves like an isotropic mater ial, where triaxiality phenomena are insignificant.