Study on the influence of edge distance ratio on the optimal interference level of cold expanded holes

Abstract Cold expansion strengthening technology can generate circumferential residual compressive stress around holes, thereby significantly improving their fatigue life. Previous studies have shown that the edge distance ratio plays a critical role in the selection of interference level of cold expanded holes, but the law of its influence on the optimal interference level is not clear. This paper employs finite element simulation to study the effects of interference levels on the circumferential residual stress, compressive zone, plastic zone, and average contact pressure around the hole edge of Aluminum alloy 7050-T7451 with different edge distance ratios. The results indicate that the optimal interference level increases with the rise of edge distance ratio, but it will tend to a constant value.