复合材料螺栓联接螺纹载荷分布规律研究

基于Abaqus有限元分析软件建立了复合材料螺栓联接的三维有限元模型，以预测复合材料螺栓联接的螺纹载荷分布，为使模型符合真实情况，将螺母支承在弹性地基上并通过Abaqus USDFLD子程序考虑了C基或SiC基复合材料拉压不对称特性。此外，本文对预测金属螺纹的载荷分布的Yamamoto方法进行了经验性的推广，使其可以反映C基或SiC基复合材料的各向异性和拉压不对称性。通过对比多组材料及几何参数下推广的Yamamoto方法（EYM）和有限元法（FEM）预测的螺纹载荷分布验证了推广的Yamamoto方法的有效性。研究结果表明：复合材料螺栓联接的载荷分布通常比金属联接的载荷分布更均匀；随着螺距与直径之比的增加，螺纹载荷分布不均程度有所增加；复合材料螺栓绕其轴线相对于螺母的转动对载荷分布几乎没有影响。

Study of load distribution in the threads of composite fasteners

Three dimensional finite element model of composite fastener was established based on Abaqus to predict the thread load distribution of composite fasteners. In order to simulate the real situation, the nut was placed on an elastic foundation and the tension-compression modulus asymmetry of C or SiC matrix composites was considered by Abaqus users' subroutine USDFLD. Furthermore, Yamamoto's method for the metal threaded connections was empirically extended to the connections by C or SiC matrix composites with special consideration of the anisotropy and tension-compression modulus asymmetry. The effectiveness of the extended Yamamoto's method (EYM) was validated by finite element method (FEM) for different materials and different geometry parameters. The results show that the load distribution of composite fasteners is usually more uniform than that of the metal fasteners. In addition, the nonuniformity of load distribution increases with the pitch-to-diameter ratio, but the relative rotation of bolt and nut almost have no effect on the load distribution.