Fatigue behavior of carbon fibre reinforced plastic and aluminum single-lap adhesive joints after the transverse pre-impact

This study aims to investigate the fatigue degradation of carbon fibre reinforced plastic (CFRP) composite and aluminum (CFRP/Al) adhesively-bonded joints after certain levels of transverse pre-impact. The CFRP/Al adhesive joints were tested post impact under quasi-static loading and different levels of cyclic loading to study fatigue behaviors. Based upon the fatigue testing results and a two-parameter Weibull distribution method, the S-N curves were established at different reliabilities to provide fundamental data for engineering applications. The experimental results showed that the fatigue life of the CFRP/Al adhesively-bonded joints decreased with increase of pre-impact energy in general. The post impact fatigue load-bearing mechanisms of the joints could come from the harmful effect caused by the pre-impact damage and beneficial effect due to mechanical interlock induced by certain plastic deformation of aluminum adherend. The adhesive failure was identified to be the major failure mode regardless of the pre-impact energy and cyclic loading levels. Meanwhile, the fatigue life of the joints decreased with increase in the cyclic loading, and was more sensitive to a higher load as indicated from the S-N curves obtained