This paper deals with the development of a numerical simulation methodology for estimating damages in LAMINATE COMPOSITE MATERIALS caused by a low-speed impact. Experimental tests were performed on LAMINATE plates reinforced with woven carbon fibers and epoxy resin. Three thickness plates were evaluated. The impact loads were transversal and punctual. Two lamina failure criteria were evaluated. The first is the maximum stress. The second is a proposed modification of the Hashin failure criterion. Four lamina degradation criteria were evaluated too. The numerical contact loads between the plate and impactor were well represented. The numerical damaged areas and lengths were similar or greater than the experimental results.

In this work, transient dynamic stress concentration in a hybrid COMPOSITE LAMINATE subjected to a sudden internal crack is examined. It is assumed that all fibers lie in one direction and the applied load acts along the direction of fibers. Two types of arrangements are considered for the fiber; square and hexagonal. Using the shear lag model, equilibrium equations are deduced, and upon proper application of initial and boundary conditions, the complete field equations are obtained using finite difference method. The results of the dynamic effect of fiber breakage on stress concentration are well examined in the presence of a second fiber type. These results are compared to those of their static values in both models. The effect of surface cracks on stress concentration, as a result of fiber breakage, is also examined. The values of dynamic stress concentrations are deduced and compared to those of a lamina. Also, the peak stress concentration during transition time for fibers to reach static equilibrium is calculated and compared with those of static values.