冲击载荷下机械零部件疲劳分析方法及其应用研究

发布时间：2018-03-05 09:14

本文选题：冲击载荷　切入点：疲劳分析　出处：《合肥工业大学》2013年硕士论文　论文类型：学位论文

【摘要】：随着我国经济建设的快速发展,工程机械在社会生产中应用越加广泛。类似矿山机械、土方机械等,工作环境较为恶劣,所受载荷随机性较大。在工作时,存在着作用时间短且作用力强的冲击载荷,且可能在一个工作循环中这种冲击载荷均存在；在一些应力较大区域产生了断裂损伤,随着冲击载荷的不断作用,裂纹快速扩展,在短时间导致机械零部件破坏,失去服役能力。开展疲劳强度设计研究,探索冲击载荷作用下的机械零部件疲劳分析方法,对提高产品竞争力有重要意义。本文主要对冲击载荷作用下机械零部件疲劳分析方法进行研究,并将此方法应用到工程机械铲运机动臂的疲劳寿命估算当中,分析其短时间失效破坏的原因,并提出优化改进方案。本文的研究内容如下：首先研究总结了现有的疲劳分析理论和断裂力学疲劳裂纹扩展相关知识,分析了冲击载荷作用后造成的初始裂纹、对机械零部件疲劳裂纹扩展寿命的影响；不同断裂韧性对疲劳裂纹扩展寿命的影响；研究总结了冲击载荷下机械零部件疲劳分析方法、设计流程及实施步骤。分析了地下铲运机动臂各损伤部位的破坏原因,将本文提出的冲击载荷下机械零部件疲劳分析方法应用于铲运机动臂疲劳寿命分析问题,并提出优化改进方案；其中对铲运机动臂进行受力计算、有限元分析及损伤部位疲劳强度校核；并基于线性和非线性疲劳累积损伤理论进行了无冲击载荷作用下的疲劳寿命估算。基于非线性有限元分析软件,对地下铲运机动臂进行了冲击动力学分析,获取动臂冲击载荷作用下各损伤部位受力情况,应用断裂力学相关知识对各损伤部位进行了疲劳裂纹扩展寿命估算,预测其可能含有的初始裂纹长度,分析冲击载荷对动臂损伤的影响,提出初步的动臂优化改进方案。
[Abstract]:With the rapid development of economic construction in our country, construction machinery is more and more widely used in social production. Similar to mine machinery and earthmoving machinery, the working environment is relatively bad, and the load is random. There exists impact load with short time and strong force, which may exist in a working cycle, and fracture damage occurs in some areas with large stress, and the crack grows rapidly with the continuous action of impact load. It is of great significance to develop the fatigue strength design research and explore the fatigue analysis method of mechanical parts under impact load to improve the competitiveness of products. In this paper, the fatigue analysis method of mechanical parts under impact load is studied, and the method is applied to estimate the fatigue life of the moving arm of construction machinery scraper, and the causes of its short-time failure are analyzed. The research contents of this paper are as follows:. Firstly, the existing theory of fatigue analysis and the related knowledge of fatigue crack propagation in fracture mechanics are summarized, and the effect of initial crack caused by impact load on fatigue crack propagation life of mechanical parts is analyzed. The effects of different fracture toughness on fatigue crack propagation life are studied and summarized, and the fatigue analysis method, design process and implementation steps of mechanical parts under impact load are summarized. In this paper, the failure reason of the damaged parts of the moving arm of the underground scraper is analyzed, and the fatigue analysis method of the mechanical parts under the impact load is applied to the fatigue life analysis of the moving arm of the scraper, and the optimization and improvement scheme is put forward. The load-bearing calculation, finite element analysis and fatigue strength checking of the damaged parts are carried out, and the fatigue life is estimated without impact load based on the linear and nonlinear fatigue cumulative damage theory. Based on the nonlinear finite element analysis software, the impact dynamics analysis of the moving arm of the underground scraper is carried out, and the stress situation of the damaged parts under the impact load of the moving arm is obtained. Based on the knowledge of fracture mechanics, the fatigue crack propagation life is estimated, the initial crack length is predicted, the effect of impact load on the damage of the arm is analyzed, and a preliminary scheme for optimization and improvement of the arm is put forward.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH114

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