A Dynamic Installation of Interference Bushing Method Based on Electromagnetic Driving to Enhance the Joining Quality of CFRP Structures

ABSTRACT Stress concentration could easily occur around the CFRP holes under external loads. To improve the fatigue performance of the CFRP joints, this study proposes a dynamic installation of interference bushing (DIB) method based on electromagnetic driving. The effects of the DIB method on the damage characteristics of the CFRP hole and the distribution of the residual stress were investigated through the combination of the experiments and finite element simulations. Additionally, the fatigue life improvement of the TC4/CFRP/TC4 double‐lap bolted joints under different expansion sizes was systematically evaluated. The results show that the damage degree of the CFRP hole increases significantly with the expansion size. Due to the die restricting the axial flow of the bushing material at the installation outlet, more damage was observed at the installation outlet than at the inlet. Because the DIB method generated beneficial residual compressive stress fields in the bushing and laminates, the average fatigue life of joints with 2% and 3% expansion reaches 15.11 and 2.17 times that of joints without expansion. However, at the 4% expansion, severe compressive damage occurred to the CFRP hole, with significant stress concentration at the installation outlet, resulting in a negative fatigue life gain of the specimens.