【作者】 周铮；

【导师】 邹广平；

【作者基本信息】 哈尔滨工程大学 ， 固体力学， 2004， 硕士

【摘要】 机械构件的设计通常是靠经验和简单的静态或准静态强度理论来完成，但是机械构件总是不可避免的要在动态的载荷下工作，而且大量的实践已经证明，在静态强度理论已经非常成熟的今天，机械构件的破坏大部分属于疲劳破坏，所以工程设计中对于动载荷问题进行疲劳强度设计已成必然。本文采用动态有限元法研究某特种车辆扭力轴在随机载荷下的动态响应，并在仿真计算的基础上对扭力轴进行了损伤容限设计、疲劳寿命计算，最后对所做的有限元仿真进行了分析研究，并对损伤容限设计以及疲劳寿命计算进行了讨论。对有限元仿真应用于该特种车辆数值仿真实验研究提供了新依据。 在求解动态有限元问题过程中，采用NEWMARK直接积分法进行求解，利用大型通用有限元分析软件ANSYS进行计算，得到某特种车辆扭力轴易破坏处单元的位移、应力的时程解。讨论了工程计算时单元的选取、模型建立所需考虑的各种因素，给出了其中一种工作状况时的仿真算例及计算结果。 在损伤容限设计中，给出了扭力轴的剩余强度的计算方法，并建立了以Paris公式为基础的裂纹扩展模型，在确定了损伤容限设计三要素中的两个之后，给出了某一工况下的检测周期的计算作为损伤容限设计的算例。在此部分中，本文还通过建立半椭圆表面裂纹数值解模型，讨论了半椭圆表面裂纹一种新近似算法在工程中应用的可行性。 建立了基于材料S-N曲线的疲劳寿命计算模型，详细说明了计算的过程中的各个因素间的关系。并在对比了算例结果的基础上，讨论两种寿命计算方法的使用。更多还原

【Abstract】 Design of machine component is commonly depending on experience or static state theory. But it’s well known that the component is generally working under dynamical load. And throw great number of practices we can find that most invalidity of components is arose by fatigue. So this thesis will use dynamic FEM (finite element method) to investigate the dynamic response of torsion bar under random dynamic load. Base on the result of simulation the thesis will give the damage tolerance design and the calculation of fatigue life. At later, it will discuss all of result of front.To solve problem of dynamic FEM, it will use the direct integral calculus method of NEWMARK to give the displacement and stress solution vs. time of nodes and elements at the place where fatigue always occurs. It will discuss the choice of element and the found of the simulation model. Then give the simulation of the torsion bar working in one of circumstances.In damage tolerance design of the torsion bar, we gave the method to enumerate remaining intension of the torsion bar. Numerical model of crack’s spread based on Paris formula would be given. As example, it would enumerate the torsion bar’s checking periods after the two of the three factors of the damage tolerance design been confirmed. A new numerical method would be used to solve the problem of enumerate of surface I type crack’s stress intensity factors, then the feasibility of vising Irwin’s approximate arithmetic of surface I type crack’s in engineering would be discussed.The method base on S-N course would be used to enumerate the fatigue life of the torsion bar. And the relationship between different factors would be discussed. Base on the result of all enumerate the two method would be discussed.更多还原