Shape Memory Polymer based Cellular Materials

We propose the concept of periodic cellular materials with programmable effective properties and present initial results from a computational study of a prototypical material that exhibits this behavior. Nonlinear FEA shows that programmed geometric imperfections at the cell level can be used to modify the effective compressive storage modulus of shape memory polymer (SMP) based periodic cellular materials after they have been manufactured. The ability of SMPs to freeze a temporary deformation for an extended period of time and the low modulus of these materials in the rubbery regime allow us to freeze controlled and reversible imperfections at the cell level following the typical temporary shape programming process for SMPs. Small geometric imperfections (2% global strain) are observed to produce variations of up to 40% in the effective initial compressive storage modulus in the prototypical material.