考虑界面端应力奇异性的螺栓连接支承面接触压力计算模型

Contact Pressure Model of Fastener Interface with Stress Singularities

将螺栓连接支承面接触问题简化为集中载荷和力矩耦合作用的有限刚度平头压模接触问题,利用BOGY特征值方程,分析双材料界面端应力奇异性发生的几何条件;依据GLADWELL接触力学理论,构建集中载荷和力矩耦合作用下平头压模接触压力计算模型,利用此模型分析螺栓预紧力、装配间隙和被连接件材料对螺栓连接支承面接触压力分布的影响规律。结果表明:在规定预紧力范围、装配等级和常用被连接件材料下,螺栓连接支承面不会发生退让接触,而界面端部出现明显的应力奇异性,其中预紧力变化对界面端应力奇异性强度影响不明显,但装配间隙和被连接件材料的变化对界面端应力奇异性强度影响显著;当被连接件材料弹性模量大于螺栓材料时,支承面内侧应力奇异性强度大于外侧,反之内侧应力奇异性强度明显小于外侧。此外,以平头压模为算例,采用有限元法验证了构建模型的准确性。

The contact problem of fastener interface is simplified an elastic punch frictionless contact subjected to normal force and bending moment. Based on BOGY’s characteristic equation, the geometrical conditions of eliminating stress singularities near bi-materials interface end are investigated. An elastic punch frictionless contact model is proposed using GLADWELL’s contact mechanics. The influence of bolt tension, assembly clearance and member materials on the contact pressure of fastener interface has been studied. The results show that under regulations bolt tension, assembly grade and member materials, the contact width doesn’t fall into the class of receding contact, but the stress singularities has been obviously happen. The effects of bolt tension on stress singularities are negligible, while influence of the assembly grade and member materials is very markedly. The stress singularities of fastener interface inside are greater than one of outside as the elastic modulus of bolt material greater than the member. Otherwise, the inside stress singularities is less than outside one. Moreover, the comparison between the finite element analysis and the theoretical calculation results shows that the proposed model can accurately predict the contact pressure distribution of fastener interface.