Thermal-mechanical-equivalent fatigue load method for mechanically fastened Hybrid-material structures

•A thermal–mechanical-equivalent fatigue load method was proposed.•A fatigue damage distribution model of fastened structure was established.•The distribution distance was defined to describe the difference.•The method was verified by fatigue tests of aluminum alloy/CFRP hybrid joints. It is difficult to verify the fatigue performance of mechanically fastened hybrid-material structures under the complex environment-load spectrum. A thermal–mechanical-equivalent fatigue load method was proposed, so that the structure has the same fatigue damage distribution under the equivalent load and the original thermal–mechanical load. By considering the influence of environmental temperature on the structural fatigue performance and the dispersion of material fatigue property, the calculation model for the fatigue damage distribution of fastened structure was established. The equivalent load could be determined according to the designed tolerance value of distribution difference. The effectiveness of method was verified by 7050-T7451 aluminum alloy/CFRP laminate plate three-bolt single-lapped hybrid fastened specimens.