基于简化模型仿真的内螺纹应力分析方法研究  

Research on stress analyzing approach of internal threads based on simplified-model simulation

作　　者：龙旦风[1,2] 黄成海[1] 徐卫国[1] 向东[2] 王一江[1] 江伟[1] 

机构地区：[1]一汽解放汽车有限公司无锡柴油机厂,无锡214026 [2]清华大学机械工程系,北京100084

出　　处：《计算力学学报》2016年第6期938-944,共7页Chinese Journal of Computational Mechanics

摘　　要：内螺纹通常是机械零件的疲劳强度薄弱部位。由于螺纹建模困难、计算量极大而且不容易收敛,工程上普遍采用无螺纹的简化模型进行仿真。简化模型的缺点是无法反映螺纹根部应力集中,所以应力结果是不正确的。针对此问题,提出一种基于简化模型仿真的内螺纹根部应力分析方法,该方法把内螺纹根部的应力分解成近源应力分量和远源应力分量,并根据它们的特点提出近源应力转换矩阵、远源应力转换矩阵的概念以及获取方法,利用这两个矩阵可以将简化模型仿真结果转换为近源应力和远源应力,然后叠加得到螺纹根部的最大应力。计算结果显示,内螺纹应力转换法基本上达到了三维细节模型的有限元计算精度,尤其是在疲劳强度薄弱部位即孔底端第一扣啮合螺纹根部,两种方法的结果吻合良好,证明了内螺纹应力转换法的精确性和有效性。Internal threads in mechanical parts are in general the weak links as to fatigue strength.However,simplified FEA models without threads rather than detailed models with threads are usually used in engineering application due to modeling difficulty,heavy computational burden and numerical convergence problems of detailed models,and thus the stress concentration at thread roots is ignored in such simulations.For this reason,a state-of-the-art calculation approach of the stress at internal-thread roots is proposed.In this approach the stress at the internal-thread root is decomposed into a near-source component and a far-source component,and correspondingly the concepts as well as obtaining technique of near-source stress conversion matrix and far-source stress conversion matrix are put forward,with which the simulation results of the simplified model can be converted to the near-source stress and farsource stress and they are summed to get the maximum stress at the thread root.Calculation results show that the stress conversion approach attains the accuracy of simulation with detailed models basically.Especially at the position easily to fatigue,namely the root of the first engaged thread near the bottom of the screwed hole,the results from the stress conversion approach agree well with those from the detailed model simulation,in consequence the validity and the accuracy of the stress conversion approach are demonstrated.

关 键 词：内螺纹 螺纹根部 应力集中 最大应力 疲劳强度 

分 类 号：TH123.4[机械工程—机械设计及理论] O346.3[理学—固体力学]