横向与轴向联合载荷作用下螺栓连接松动特性分析

Analysis of loosening characteristics of bolted joint subjectedto combined transverse and axial loads

螺栓连接结构通常受到横向和轴向联合循环载荷作用,其松动行为相比于横向或轴向单向循环载荷作用更为复杂。应用有限元方法,建立考虑螺纹旋转特性的三维螺栓连接数值模型,计算分析螺栓连接在不同横向和轴向谐波激励载荷幅值、装配预紧力、接触面摩擦因数等因素影响下的螺栓连接松动行为,获得了可对螺栓临界松动载荷进行预测的螺栓松动速率相对横向和轴向载荷幅值的数学模型。研究结果表明:当横向激励载荷幅值小于一定量值时,轴向激励载荷幅值增大会加快螺栓松动;当横向激励载荷幅值大于一定量值时,轴向激励载荷幅值增大会抑制螺栓松动。另外,预紧力、界面摩擦因数越大,横向载荷幅值越小,螺栓越难松动。相比单独横向载荷作用,联合载荷作用下螺栓松动速率对载荷幅值、预紧力、摩擦因数更敏感。研究深化了横向与轴向联合载荷作用下螺栓松动行为的认识。

Bolted joints are usually subjected to combined transverse and axial cyclic loads.The loosening behavior of bolted joint is more complicated than that of transverse or axial unidirectional cyclic loading.Based on the finite element method,a three-dimensional numerical model of bolted joint considering screw rotation characteristics is established.The loosening behavior of bolted joint under the influence of different transverse and axial excitation load amplitudes,assembly preload,friction coefficient of contact surface and other factors is calculated and analyzed.A mathematical model of bolt loosening rate relative to transverse and axial load amplitudes is obtained,which can be used to predict the critical load of bolt loosening.The results show that the increase of axial excitation load amplitude will accelerate bolt loosening while the amplitude of transverse excitation load is less than a certain value.However,the increase of axial excitation load amplitude will inhibit bolt loosening when the amplitude of transverse excitation load is greater than a certain value.In addition,the greater the preload and interface friction coefficient,the smaller the amplitude of transverse load,and the more difficult it is for the bolt to loosen.Compared with single axial load,the bolt loosening rate under combined load is more sensitive to load amplitude,preload and friction coefficient.The research deepens the understanding of bolt loosening behavior under combined transverse and axial loads.