Cohesive modeling of low-velocity impact damage in layered functionally graded beams

Numerical analysis of the low-velocity impact damage of a layered composite beam with a functionally graded core is performed using the multiple-isoparametric cohesive volume finite element (MCVFE) scheme. A mixed-mode intrinsic cohesive zone model is used to simulate the spontaneous damage initiation and growth in this work. The inhomogeneous Young’s modulus variation is assumed to be symmetric about the neutral plane. Our parametric simulations showed that the energetics of damage is altered by the presence of a functionally graded core. The effect of including a functionally graded core is to advance the time of fracture initiation compared to a cross-ply $(90^0)$ core. The assumed symmetry and linear inhomogeneity leads to the energetics for the graded core to be similar to those observed for a $45^0$ core plyorientation