Transverse impact behaviors of four-step 3-D rectangular braided composites from unit-cell approach

Transverse impact behaviors of 3-D carbon/epoxy braided composite are reported in experimental and finite element analysis (FEA) approaches. In the experimental approach, the quasi-static penetration and transverse impact behaviors were tested to obtain load-displacement curves and fracture morphologies of the braided composite. In FEA, a unit cell model was established to derive the constitutive equation and failure criteria. Based on the model, a user-defined material subroutine (VUMAT) was written and connected with commercial FEA code ABAQUS/Explicit to calculate the impact damage. Good agreements between the experimental and FEA results prove the validity of the unit cell model and the subroutine VUMAT.