线膨胀系数对轮盘紧固螺栓力学性能的影响

Analysis of Linear Expansion Coefficient on Mechanical Properties of Wheel-Mounted Brake Disc Fastening Bolts

基于热-机耦合有限元法,针对轮装制动盘结构,建立全六面体精细有限元模型,并对螺栓施加预紧力,通过对制动盘摩擦环施加热流密度的方式模拟制动时的传热过程,分析了螺栓材料线膨胀系数对螺栓温度场、应力场以及轴向力的影响,计算结果表明:线膨胀系数增大可以适当减少材料的应力幅值和轴向力变化幅值,但制动结束后会导致螺栓预紧力下降,应综合考虑选择合适的线膨胀系数;在典型制动工况下,螺栓的最大轴向力与初始预紧力相比增幅很大,在分析制动盘紧固螺栓力学性能时应全面考虑热应力的影响.

Based on thermo mechanical coupling finite element method,a hexahedral fine finite element model for the wheel mounted brake disc structure is established,and the pretightening force is applied to the bolt.The heat transfer process during braking is simulated by applying heating flow density to the friction ring of the brake disc.The influence of the linear expansion coefficient of the bolt materials on the temperature field,stress field and axial force of the bolt is analyzed.The results show that the increase of linear expansion coefficient can reduce the stress amplitude and axial force amplitude of the materials properly,but the pretightening force of the bolt will decrease after the brake is finished,so the appropriate linear expansion coefficient should be selected comprehensively.Under typical braking conditions,the maximum axial force of the bolt is increased greatly compared with the initial preload.The influence of the thermal stress should be fully considered when analyzing the mechanical properties of the brake disc fastening bolt.