Fatigue behaviors of aluminum alloy butt joints with backing plates: Experimental testing and traction stress modeling

•The fatigue properties and failure modes of butt joints with backing plates are studied by conducting fatigue tests and UPAT.•A method for predicting failure modes of butt joints with backing plates is proposed.•The fatigue performance of butt joints with backing plates is evaluated based on the IIW and BS7608 standards.•The effect of angular misalignment on the failure modes of test specimens is investigated.•The effect of failure modes on the fatigue properties of the test specimens is studied.