A PHENOMENOLOGICAL 3-DIMENSIONAL RATE-INDEPENDENT CONTINUUM DAMAGE MODEL FOR HIGHLY FILLED POLYMERS - FORMULATION AND COMPUTATIONAL ASPECTS

A three-dimensional rate-independent model for damage in highly filled polymers is presented. The model generalizes the one-dimensional theo ry proposed by Gurtin and Francis [(1981) Simple rate-independent mode l for damage. J. Spacecraft 18(3), 285-286] to describe the behaviour of highly filled solid propellants. The objective is to simulate the M ullins effect observed when these materials are subjected to alternate loading. A simple algorithm for integration of the proposed constitut ive equations is presented, which is formulated in terms of principal directions. A closed form of the spatial tangent modulus for two-dimen sional applications is derived. This provides the basis for the Newton -Raphson iterative scheme for solution of the associated incremental b oundary value problem. The suitability of the proposed model to large scale computations is demonstrated by means of finite element simulati ons.