The effect of tightening torque on the strength of composite-metal hybrid joints

Abstract In the manufacturing and assembly process of aircraft composite-metal hybrid structures, tightening torque is one of the important factors that control assembly quality and affect connection strength. This paper experimentally studies the mechanical properties of composite-metal single-bolt single-lap joints under different tightening torques, reveals the impact mechanism of different tightening torques on the manufacturing and assembly of composite-metal hybrid structures, and also establishes a finite element analysis model of hybrid connection structure considering the influence of drilling and assembly processes. The results show that the ultimate load of the composite-metal connection structure increased with the increase of tightening torque. When the tightening torques were 3 N·m, 6 N·m, and 9 N·m, the ultimate failure loads of the composite-metal hybrid joints were 12.9 kN, 13.8 kN, and 14.6 kN respectively.