Symmetric hole stress concentration in a hybrid composite lamina subjected to matrix plasticity

In this paper, hole stress concentrations in long fibers and their surrounding matrix bays is examined in a hybrid composite lamina. It is assumed that all fibers lie in one direction while loaded by a force p at infinity in the direction of fibers. The width of the lamina is considered to be finite and bears a hole as a defect. Due to the presence of excessive shear stress in the matrix bays bounding the hole, a yielded zone of size 2 a o is developed around the hole. Shear lag model (SLM) is used to drive the displacement and stress fields. The resulting equations are solved analytically based on boundary and continuity conditions. It is shown that the shape and size of the hole, as well as length of the plastic zone, have considerable effect on stress concentrations within the lamina. Compared to a lamina with a single type fiber, a hybridized model shows lower stress concentrations in High modulus (HM) fibers bounding the hole as opposed to those of Low modulus fibers (LM) subjected to the same condition. Moreover, hole shape and size, ratio of extensional stiffness of LM to HM fibers, and size of the plastic zone seem to have considerable effect on shear and normal stresses in the matrix and fibers, respectively.