在役压力容器容限分析

【作者】 王珉；

【导师】 李建华； 郎福元；

【作者基本信息】 甘肃工业大学 ， 机械制造及其自动化， 2001， 硕士

【摘要】 本文是甘肃省劳动厅资助项目“在役压力容器容限分析”的一部分。 本文在下面几方面作了研究并取得成果： （1）首先回顾和总结了在役压力容器缺陷评定和容限分析的发展现状，并主要对失效评定图、概率方法、智能方法（尤其人工神经网络方法）、疲劳工程评定方法新进展进行了综述。并且对今后的发展方向做出展望。 （2）针对工程上常见的破坏性极大的压力容器的疲劳问题，由于其数据的分散性，目前的计算寿命很保守。本文提出了一个适于压力容器的弹塑性疲劳裂纹扩展率计算公式，该公式采用弹塑性分离的形式，主要适用于Paris区和高速扩展区的一部分。通过公式的验证，说明该公式的其合理性，并给出了便于应用的工程计算方法。 （3）目前工程上广泛应用Paris公式来描述裂纹扩展速率与应力强度因子的关系。一般来说Paris公式的参数可以通过实验获得。为达到减少实验次数，充分利用已有数据和节省时间的目的。本文采用基于神经网络的方法对压力容器疲劳裂纹扩展率公式（Paris公式）中的两个材料常数进行了估算，用人工神经网络建立一个学习系统，方便的获得各种材料的疲劳裂纹扩展率。通过计算和实验数据的比较，证明了利用神经网络进行疲劳裂纹扩展率的估算是可行的。 （4）应用该公式对一种压力容器进行了寿命估算和LBB（破前漏）分析。 （5）复合型裂纹在工程上是普遍存在的，由于它的应力状态的复杂性，工程上在一系列假设的前提下提出了一些准则。这与强度理论的思想是一致的。基于二者之间的共性，建立了一个基于统一强度理论的复合型裂纹断裂准则。更多还原

【Abstract】 This paper is one part of the project the fracture and fatigue life of pressure vessels? which is supported by science foundation of Department of Labor and Social Security of GanSu Province. Based on investigation, the following results are obtained: (1) Firstly, this paper reviewed briefly the development of safety assessment for pressure vessels. That include: 0 the development of FAD technology; ?the application of probabilistic method; he application of fuzzy method(esp. artificial neural network); Othe new advances on engineering assessment methods for fatigue. In the last, the developing direction in the future is prospected in the paper. (2)The fatigue of Pressure Vessel is a popular problem in engineering. The method of estimate fatigue life is very shorter than examination because of the dispersion of examination data. A formula is presented in this paper that is suitable to estimate fatigue crack growth Rate of the pressure vessels. The formula which separate the elastic and plastic component can be used in Paris zone and quickly growth zone. in this paper, the reasonableness is interpreted and the estimation method that could be used easily is presented. The application of this formula can improve the precision of calculate. (3) It has been widely used that the Paris law can discripted the relation between the fatigue crack growth rate and the stress intensity factor. The parameter of Paris law can be achieved by experiment. In this paper, a manner based on the artificial neural network is presented, which can estimate the parameter of Paris law in order to reduce experiments, take advantage of data and save times. Through comparing the results of estimation with experiment data, we prove that it抯 practical to estimate the rate by neural network method. (4)the fatigue life of a pressure vessel is estimated by this formula, and it抯 LBB analysis is presented. (5)Mixed mode cracks is in existence universally. Because of its complexity of combined stresses just as strength theory , a lot of mixed mode fracture criteria are presented based on some hypothesis. In this paper a mixed mode fracture criteria was established which based on the Yu’s unified strength theory from the commonness of both theory.更多还原