Numerical simulation of three-point bending fatigue of four-step 3-D braided rectangular composite under different stress levels from unit-cell approach

This paper reports the three-point bending fatigue behavior of 3-D carbon/epoxy braided composite in experimental and finite element analyses (FEAs) approaches. In the experimental approach, the stiffness degradation and maximum deflection curves were obtained to illustrate the relationship between applied stress levels and number of cycles to failure. In FEA approach, a user-defined material subroutine UMAT which characterizes the stiffness matrix and fatigue damage evolution of the 3-D braided composite was developed. It was incorporated with a finite element code ABAQUS/Standard to calculate the stiffness degradation and maximum deflection of the 3-D braided composite during each loading cycle. From the comparisons between experimental and FEA results, good agreements prove the validity of the unit cell model and the subroutine UMAT.

► We study the bending fatigue of 3-D braided composite with finite element method from unit-cell approach. ► We examine the stiffness degradation and maximum deflection curve 3-D braided composite. ► We develop a user-defined material subroutine UMAT of 3-D braided composite. ► A good agreements are found between the finite element simulation and experiment.