Effect of hygrothermal and thermal aging on the fatigue and static strength of mechanical and hybrid single lap joint

Abstract

In this study, the effect of hygrothermal (in tap water at 53 °C for 20 days) and thermal (53 °C for 20 days) ageing on the mechanical (OB) and hybrid (HBB) joints with similar (AL/AL and CFRP/CFRP) and dissimilar (AL/CFRP) adherends, is investigated on single lap joint (SLJ) configuration. Three- point bending strength of the un-aged, aged joints were measured and compared for static and fatigue testing at different load levels (50, 60, and 70 % of static load level) of 16 Hz frequency. The results showed that HBB-CFRP/CFRP SLJs has the highest bending strength. Both the thermal and hygrothermal aging showed to have a noticeable effect on the static bending properties of the SLJs with similar and dissimilar adherends. Al/CFRP had the longest fatigue life between the OB samples while CFRP/CFRP had the longest fatigue life in the HBB SLJs. The load percent and aging both reduce the number of cycles to failure and change the mode of failure of the joints.