扭动微动下亚表面接触应力分布规律

The distribution of contact stress on the subsurface under torsional fretting

求解螺栓连接结构在扭动微动下的应力分布时,通常接触体的亚表面应力是由表面应力推导而得。而扭矩卸载时,由于接触表面切向力的表达式非常复杂,很难获得亚表面应力分布规律,为此引入半解析法求解亚表面应力分布特征。首先,根据加、卸载时的切向力和扭矩方程,获得加、卸载时的表面切向应力分布规律;然后,利用半解析法计算出加载时的亚表面应力,并与解析法的结果进行对比,验证半解析法的正确性,再用半解析法计算出卸载时的亚表面应力;最后,探讨了扭矩和摩擦系数对卸载时应力分布的影响规律。研究表明:卸载时,最大应力出现在接触表面或接触中心的正下方;随着扭矩的减小,整体应力减小,而最大应力先减小后不变;随着摩擦系数的增大,整体应力、最大应力值增大;应力值相对较小时,最大应力点出现在亚表面上。

The subsurface stress plays an important role in the stress distribution of the bolted joint under the torsional fretting. However, it is difficult to obtain subsurface stress by the complex equation of tangential stress. In this paper, a semi-analytical method is proposed to solve the subsurface stress distribution of the bolted joint. Firstly, the tangential stress distribution during loading and unloading can be obtained based on the tangential force and torque equation. Then, the semi-analytical method is used to calculate the subsurface stress during loading and unloading, which is compared to the results from the analytical method. Finally, influences of torque and friction coefficient on the stress distribution during unloading are analyzed. Results show that the maximum stress appears directly below the contact center during unloading, as the torque decreases, the overall stress decreases, while the maximum stress firstly decreases and then remains constant. In addition, both the overall stress and the maximum stress value increase with the increase of the coefficient of friction, and the maximum stress appears on the subsurface when the stress value is small.