Impact Damage of 3D Cellular Woven Composite from Unit-cell Level Analysis

The high ratio of strength/area density of 3D cellular woven composite (3DCWC) leads the widely potential application of the composite in aircraft, vehicle, and sports facilities. The objectives of this investigation are to characterize the microstructures, impact responses, and failure modes of the 3DCWC under transverse impact. The 3D woven fabrics and composites were manufactured based on 3D angle-interlock woven fabric with cellular structures. The impact responses and energy absorption of the 3DCWC were tested with a modified split Hopkinson bar apparatus. A unit-cell model of the composite was established from the microstructure features, i.e., same fiber volume fraction and mechanical behaviors. A user subroutine VUMAT (FORTRAN Vectorized User-Material) was developed and connected with a commercial available finite element method (FEM) software package Abaqus/Explicit for calculating the impact responses of the composite. This subroutine describes the elasto-plastic constitutive equations of the unit-cell, maximum stress failure criteria, and critical damage area failure criteria. It was found that there is a good agreement of the impact load-displacement, failure modes between FEM calculation and experimental. This proves the validity of the unit-cell model, failure criteria and user-defined subroutine VUMAT. The user-defined subroutine VUMAT can also be extended to characterize the impact responses of the 3DCWC engineering structures.