FAILURE PREDICTION OF FIBER REINFORCED LAMINATED COMPOSITE PLATES UNDER LOW VELOCITY IMPACT

摘要

The low velocity impact on composites has been studied as it leads to serious damage. The damage initiates as an intra ply matrix crack due to shear or bending which propagates further into the interface causing de-lamination between dissimilar plies and fiber breakage. This damage evolves with time and adversely affects the mechanical properties and strength of the composite. Since, multiple cracks in the ply are difficult to track, a progressive damage mechanics approach is used to model this failure. The inter ply failure is modeled using cohesive surfaces between the plies. The low velocity impact on composite plate is studied using finite element method. Impact parameters like velocity of impactor, the mass of the impactor and elastic properties of the material etc. are considered. An explicit central difference integration scheme is used to solve for displacements and impact forces. Progressive damage and failure in composites is modeled; an efficient algorithm has been developed and implemented in the FE code ABAQUS through a user-defined subroutine (VUMAT). Reduced integration yields satisfactory results for the impactor velocity less than or equal to 3 m/s for larger mass impact. However, full integration is recommended to obtain the satisfactory results for the (impactor velocity beyond 3 m/s), high velocity impact involving small masses. For the low velocity impact, the peak contact force and displacement are linear functions of impactor velocity for a constant mass. However, a nonlinear behavior is observed for the variation of mass with a constant striking velocity.