微动损伤对复合材料螺栓连接预紧力松弛的影响

开展了横向循环载荷下复合材料螺栓连接件预紧力松弛试验，探究了材料疲劳损伤与接触面微动磨损联合作用下螺栓连接预紧力松弛过程。基于有限元软件ABAQUS，采用Archard磨损模型和ALE（Arbitrary Lagrangian-Eulerian）自适应网格技术，编制了适用于连接结构微动磨损的UMESHMOTION子程序，建立了分析连接支承面微动磨损的计算模型；利用子程序UMAT编制了Shokrieh和Lessard提出的疲劳累积损伤定量分析程序。在此基础上分析了复合材料疲劳损伤、螺孔伸长及接触磨损的耦合作用下预紧力随循环周次变化的机制，与实验结果进行对比，验证了所提出的预测方法的合理性、有效性。 

Effects of fretting damage on preload relaxation in bolted composite joints

Fatigue tests for determining the preload relaxation of composite bolted joints under transverse cyclic loading and exploring the effects of fatigue damage and fretting wear on the preload decay were carried out. The Archard wear model and the ALE (Arbitrary Lagrangian-Eulerian) adaptive meshing technology were used to calculate the fretting wear between contact surfaces and were implemented in the finite element code ABAQUS with UMESHMOTION subroutine; a progressive fatigue damage model proposed by Shokrieh and Lessard was employed to perform the failure analysis, and material property degradation was programmed by using UMAT subroutine in ABAQUS. Based on this analysis, the mechanism of the preload changing under cyclic loads attributes to the coupling action of the fatigue damage in bolt connection, the bolt-hole elongation and the contact wear. Compared with the experimental results, the rationality and validity of the proposed method were verified.