UNIFORMITY OF STRESSES WITHIN AN ELLIPTICAL INHOMOGENEITY COATED BY AN INTERPHASE LAYER WITH EIGENSTRAINS

We study the state of stress inside an elliptical elastic inhomogeneity which is bonded to an infinite matrix through an intermediate confocal interphase layer undergoing uniform in-plane eigenstrains. A simple condition is found that ensures that the internal stress state is uniform but in general nonhydrostatic. This condition can be considered as a restriction on the imposed eigenstrains for given geometric and material parameters of the three-phase composite. Once this condition is met, the corresponding stress distributions are obtained in elementary form. In particular, the mean stress is found to be uniform within the interphase layer.