Finite element analysis of the damage mechanism of 3D braided composites under high-velocity impact

The integrated near-net-shape structure of 3D braided composites provides excellent impact resistant properties over laminated composites. However, the load distribution and damage mechanism throughout the braided structures become more complicated. In this paper, a finite element model based on three unit-cells is established to assess the penetration process of 3D braided composites under high-velocity impact. A 3D rate-dependent constitutive model is employed to determine the constituent behavior in the three unit-cells. An instantaneous degradation scheme is proposed initiated by appropriate failure criteria of yarns and matrix. All these constitutive models are coded by a user-material subroutine VUMAT developed in ABAQUS/Explicit. The whole process of ballistic damage evolution of 3D braided composites is simulated, and the impact resistance and damage mechanisms are analyzed in detail in the simulation process. The effects of impact velocity on the ballistic properties and energy absorption characteristics of the composite structures are also discussed.