高强度螺栓在预紧力及微裂纹作用下的有限元分析

Finite Element Analysis of High-strength Bolts under the Action of Preload and Microcrack

采用考虑螺纹细节的有限元模型对高强度螺栓在预紧力作用下的受力状况进行了仿真分析。研究了四棱锥形开口微裂纹及近表面椭圆形微裂纹对螺栓表面应力集中处受力分布的影响。结果表明:应力集中主要产生于最末端螺纹处以及旋合段的第一、二扣螺纹处,螺牙根部是同一横截面上的最大等效应力处;微裂纹的存在会极大地加强应力集中,并且最末端螺纹比旋合段螺纹对微裂纹更敏感。此外,四棱锥形开口微裂纹趋于周向扩展,近表面椭圆形微裂纹趋于向表面扩展。

The finite element model considering the thread detail is used to simulate the stress state of the high-strength bolt under the preload force. The effects of the opening microcracks of the quadrilateral pyramid and the elliptical microcracks on the near-surface of the bolt on the stress distribution at the stress surface of the bolt are studied. The results show that the stress concentration is mainly generated at the end of the thread and the first and second threads of the screwing section. The root of the screw is the maximum equivalent stress on the same cross section;the presence of microcracks will greatly enhance the stress concentration. And the end threads are more sensitive to microcracks than the screw threads. In addition, the quadrangular pyramidal opening microcracks tend to expand circumferentially, and the near-surface elliptical microcracks tend to expand toward the surface.