DETERMINATION OF RESIDUAL-STRESSES USING INCREMENTAL LINEAR ELASTICITY

An incremental linear elastic constitutive equation was used to calculate the residual stresses generated in polymer systems, with emphasis on thermosetting systems which are curing under dimensionally constrained conditions. The equations necessary to calculate the stress due to cure, shrinkage due to cure, thermal stress, glass transition temperature and thermal expansion coefficient as functions of the polymerization history are derived. Residual stress data are presented for an epoxy cured under conditions of uniaxial (one-dimensional) and volumetric (three-dimensional) constraint. It was found that for anhydridecured epoxies the unaxial stresses due to cure are small, especially in comparison to the residual uniaxial thermal stress. For conditions of volumetric constraint it was found that both cure stresses and thermal stresses are large in amine-cured epoxy resins.