Numerical study of the effect of torsional fatigue loading on the energy absorption of composite tubes

Abstract A three‐dimensional finite element model is developed to predict the effect of torsional fatigue loading on the energy absorption of unidirectional carbon/epoxy (AS4/3501‐6) composite tubes. Progressive fatigue damage model for fatigue loading and progressive failure model for axial velocity impact are implemented separately in the Abaqus software through user subroutine VUMAT. Each model is validated by the experimental data available in literature and good agreement is observed between the simulation results and experimental data. Then, these two models are sequentially applied to the composite tube with three different layups. The tube is first placed under torsional fatigue loading and a number of predefined loading cycles is applied. During this loading, the mechanical properties of the material are degraded based on sudden and gradual material properties degradation rules. Next, the fatigued tube is placed under axial impact loading. The results show that by increasing the number of fatigue cycles, the tube's ability to absorb energy is first reduced uniformly but in a particular cycle, due to the sudden drop in the shear mechanical properties of the material, the amount of energy absorption drops sharply and the tube loses its ability to absorb energy before it's catastrophic fatigue failure.