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应用有限元法预测了轮毂螺栓断裂的原因。通过拉伸实验获得了JIS SCM435热处理后的力学性能,应用理论计算得到某轮毂螺栓的摩擦系数,基于Normalized C&L韧性断裂准则计算得到该螺栓的断裂系数。应用DEFORM-3D仿真软件对该螺栓的断裂过程进行了有限元模拟分析。结果表明,该轮毂螺栓的断裂是由于外力施加扭矩过大所导致。当螺母开始拧紧时,在剪力作用下,与螺母咬合的第一圈螺纹牙根处应力最大,当拧紧达到一定程度后,第一圈的螺纹牙受到严重破坏,观察螺栓内部应力变化时,螺母下方未咬合螺纹段的中心处的应力开始增大,并向外扩散,表明此时拉力起主导作用。在最后的断裂阶段,拉力逐渐减小,剪力开始起主导作用,从产生裂痕的牙根表面处,由外向内以45°形式产生断裂,与实物断裂形貌基本一致。研究结果可作为推测断裂原因的参考。
Finite element method is used to predict the cause of hub bolt breakage. The mechanical properties after heat treatment of JIS SCM435 were obtained through tensile test. The friction coefficient of a hub bolt was calculated theoretically. The fracture coefficient of the bolt was calculated based on Normalized C & L toughness fracture criterion. The fracture process of the bolt was simulated by DEFORM-3D simulation software. The results show that the hub bolt rupture is due to external torque is too large. When the nut begins to tighten, under the action of shearing force, the first ring thread with the nut bite the maximum stress, when the tightening up to a certain extent, the first thread of the thread was severely damaged, observe the bolt internal stress changes, the nut The stress at the center of the lower unmembered thread segment began to increase and spread outwards, indicating that the pulling force played a dominant role at this time. At the final stage of fracture, the tensile force gradually decreases and the shear force begins to play a dominant role. At the root surface of the cracked fracture, the fracture occurs from 45 ° outwardly to inwardly, which is consistent with the physical fracture appearance. The results can be used as a reference for speculating the reason of fracture.