Plastic Deformation of a Laminated Plate With a Hole

The elastic-plastic behavior of a (0/90) symmetric FP-Al plate containing a circular hole is investigated using the finite-element method. Of principal concern are plastic yielding at the circular hole and fracture of the plate caused by failure of the fiber at the hole. The results illustrate the significance of plasticity in deformation of metal-matrix composites. The behavior of the laminated plate is compared with that of a geometrically similar plate made of an unreinforced matrix material, for uniaxial loading/unloading/reloading sequences. The comparison reveals significant differences in the role of plastic deformation in these two materials. Specifically, plastic yielding in the matrix of the laminated plate at the circular hole leads to a substantial increase in the local stress concentration in the elastic fibers adjacent to the hole boundary. Also, it is found that the fiber reinforcement causes a large increase in the stiffness and strength of the composite, but only a minor elevation of its yield strength. Therefore, to take advantage of the mechanical properties of the metal matrix composite material, it is necessary to admit working loads which exceed its elastic limit.