Numerical simulation of hybrid CFRP/Al hole-clinched joints at different tensile shear loading rates

Abstract

In this study, the tensile-shear damage mechanisms and mechanical responses of carbon fiber reinforced plastic (CFRP)/Al clinched joints were investigated at different loading rates. A continuous damage model was developed that incorporated strain rate effects and nonlinear in-plane shear behaviors. The nonlinear in-plane shear behaviors included two stages: the plastic deformation stage and the strengthening by fiber rotation stage. The finite element algorithm was implemented by applying the VUMAT user subroutine in Abaqus to analyze the responses of the CFRP/Al clinched joints with three layups (orthogonal, diagonal, and hybrid). The experimental and simulation results were highly consistent in terms of the joint failure modes, damage evolution predictions and load–displacement responses. The strain rate effects on CFRP damage were determined. Under high-strain-rate conditions, the average reductions in deformation required for the various damage modes were 51.5%, 13.2% and 13.1% for the orthogonal, diagonal and hybrid layup joints, respectively. Furthermore, the corresponding average area reductions in the damage modes were 16.0%, 41.7% and 70.6%, respectively. Then, the strain rate effects on joint mechanical performance were evaluated. The mechanical properties of the orthogonal layup joints did not exhibit strain rate sensitivity, whereas the energy absorption levels decreased by 21.1% and 36.6% for the diagonal and hybrid layup joints, respectively. For the diagonal layup joints, the maximum load increased by 22.4% under dynamic loading.