【作者】 王银海；

【导师】 谭文锋；

【作者基本信息】 燕山大学 ， 工程力学， 2010， 硕士

【摘要】 金属构件疲劳失效是许多工程领域中关系到机械设备与工程结构使用安全性以及成本经济性的一个重要因素,由于工程需要的迫切性与疲劳问题的复杂性,将损伤力学应用于疲劳分析是一个重要的研究方向。疲劳失效主要由两部分组成:裂纹形成和裂纹扩展。对于裂纹形成阶段,传统的分析方法还存在一定的难度;而裂纹扩展阶段,目前大多是采用断裂力学方法进行分析。相对而言,对于裂纹扩展阶段的分析,要比裂纹形成阶段的分析成熟合理,所以,对疲劳裂纹形成寿命问题的研究有一定的意义。本文主要是研究建立大范围损伤条件下板状构件疲劳裂纹形成问题的耦联系统及能量原理,并应用其推导板状构件疲劳裂纹形成寿命预估的封闭解答,得到分析板状构件疲劳裂纹形成寿命的新体系。应用虚功原理推导了平面应力板状构件疲劳裂纹形成寿命的封闭解。对大范围损伤条件下平面应力板状构件的疲劳裂纹形成寿命预估问题,采用变分原理进行了分析。定义了该问题的耦联系统,建立了该耦联系统的零差功原理、耦联势能原理和耦联余能原理。应用耦联势能原理导出了平面应力板状构件在大范围损伤条件下的疲劳裂纹形成寿命预估的封闭解。作为本文方法的应用,对平面应力板状构件疲劳裂纹形成寿命进行了计算,给出了预估其疲劳裂纹形成寿命的方法,并计算了算例。与试验数据进行比较,预测结果较为理想,在大范围损伤的情况下,采用此方法预估板状构件的疲劳裂纹形成寿命是可行的,并预估了不同几何形状的板状构件疲劳裂纹形成寿命。更多还原

【Abstract】 Fatigue failure of metal component is an important factor relating to mechanical equipment and engineering structural use safety and cost economy in many engineerings. And the application of damage mechanics in fatigue analysis is becoming an important research direction owing to the urgency of engineering requirements and the complexity of fatigue problems.The fatigue failure process consists of two stages:fatigue crack initiation and crack propagation. It has certain difficulty in the use of traditional analysis method in analyzing crack initiation. Second, crack propagation, in which stage fracture mechanics method is mostly adopted at present. Comparatively speaking, the analysis of crack propagation stage is more mature and reasonable than that of crack initiation stage, therefore, the study on problem of crack initiation lives has certain significance.This paper mainly studies the establishment of energy principle and coupled system of fatigue crack initiation problem of plate-like component with large range damage conditions, then the closed form solution of prediction to crack initiation lives of plate-like components is derived based on the above achievements, and finally, a new system on the analysis to crack initiation lives of plate-like components is obtained.Applying virtual work principle, the closed form solution is obtained for evaluating crack initiation lives of a plate-like component under plane stress. Applying variational principles, fatigue crack initiation lives is evaluated for a plate-like component with large range damage. Coupled system is defined firstly, then zero different work principle, coupled potential energy principle and coupled complementary energy principle are established. Applying coupled potential energy principle, the closed form solution is obtained for evaluating crack initiation lives of a plate-like component under plane stress. As an application, fatigue crack initiation lives of the plate-like components is evaluated, the method is given for evaluating its fatigue crack initiation lives. Compared with the experimental data to predict the results more desirable, the use of this method predicts fatigue crack initiation lives of plate-like component with large range damage is feasible,and predicts fatigue crack initiation lives of different geometric shapes of plate-like components.更多还原