The effects of triaxial constraint on toughening mechanisms of rubber-modified epoxy system

The effects of triaxial constraint on the capacity of particle cavitation and matrix yielding of polymer blends with rubber particles are studied by three-dimensional elastic-plastic finite element analysis. The interaction between particles is taken into account by the 3D periodic microstructural model. The results show that high triaxial constraints lead to significant difference of the 3D local stress and strain fields before and after cavitation. It is concluded that rubber cavitation and matrix shear yielding are two coupling and stimulating mechanisms, which occurs first depends on the properties of rubber particles and matrix as well as the degree of triaxial constraint. The relief of high triaxiality by rubber cavitation plays an important role in the toughening process.