含缺陷厚壁压力容器J积分计算方法及失效评定曲线方法研究

发布时间：2018-01-15 09:29

本文关键词：含缺陷厚壁压力容器J积分计算方法及失效评定曲线方法研究　出处：《华东理工大学》2012年硕士论文　论文类型：学位论文

【摘要】：厚壁压力容器特别是大型的厚壁压力容器长期承受高温高压和化学介质的作用,在极端的工作条件下运行,属于特种设备范畴之内。而裂纹和缺陷的扩展是造成压力容器事故的重要原因,因此结构完整性评定是判断压力容器是否能够安全运行最重要的内容之一。而结构完整性评定中的J积分工程估算方法和失效评定曲线技术是研究者们长期关注和研究的重要课题。作者基于上述关键技术展开了研究,主要包括以下内容： 1.针对大型厚壁压力容器,以内压作用下内表面半椭圆裂纹厚壁圆筒为模型,利用ABAQUS软件进行了大量建模计算和比较,发现EPRI延性断裂手册全塑性解针对厚壁压力容器的适用性较弱的问题。讨论了全塑性解计算方法,重新给出大量的内压作用下内表面半椭圆裂纹厚壁圆筒的全塑性解,补充了EPRI延性断裂手册内容。 2.基于等效远场应力法,给出了统一的J估算表达式和针对于厚壁压力容器载荷比形式的n无关全塑性解系数x0手册；针对等效远场应力法只能用应力形式计算J积分的问题,推导了基于载荷比形式x0解的J积分计算方法；验证了载荷比形式x0的精度和本文中给出的J积分计算方法的有效性。 3.针对特定材料的大型厚壁压力容器,文中以R6的选择2失效评定曲线为基础,以R6的选择3失效评定曲线为标准,利用转化应力σTeff建立了基于载荷比形式x0解的失效评定曲线。该曲线无需通过J积分的计算,只需知道材料真应力真应变关系即可得到；不仅具有R6选择3的精度和R6选择2与结构无关的特性,并且具有计算方法简便的优点,使文中的J积分计算方法提升到了实际工程应用层面。
[Abstract]:Thick-walled pressure vessels, especially large thick-walled pressure vessels, operate under extreme working conditions under the action of high temperature and high pressure and chemical medium for a long time. It belongs to the category of special equipment, and the crack and defect propagation is the important cause of the accident of pressure vessel. Therefore, structural integrity assessment is one of the most important contents in judging whether the pressure vessel can operate safely. The J integral engineering estimation method and failure assessment curve technique in structural integrity assessment are concerned by researchers for a long time. The author has carried out the research based on the above key technologies. It mainly includes the following: 1. For a large thick-walled pressure vessel, a large number of modeling calculations and comparisons have been carried out by using ABAQUS software to model the inner surface semi-elliptical cracked thick wall cylinder under internal pressure. It is found that the full plastic solution of EPRI ductile fracture manual is weak for the applicability of thick-walled pressure vessel, and the calculation method of full plastic solution is discussed. The full plastic solution of the thick wall cylinder with semi-elliptic crack on the inner surface under a large amount of internal pressure is given again, which complements the EPRI ductile fracture manual. 2. Based on the equivalent far-field stress method, the unified J-estimation expression and the n-independent fully plastic solution coefficient x0 for the form of load ratio of thick-walled pressure vessel are given. In order to solve the problem that the equivalent far-field stress method can only calculate the J-integral in the form of stress, the J-integral calculation method based on the form of load ratio x _ 0 is derived. The accuracy of the load ratio form x0 and the validity of the J integral calculation method given in this paper are verified. 3. For large thick-walled pressure vessels with specific materials, this paper bases on the failure evaluation curve of choice 2 of R6 and takes the curve of failure assessment of choice 3 of R6 as the standard. The failure evaluation curve based on the form of load ratio x 0 is established by means of transformation stress 蟽 Teff. The curve does not need to be calculated by J integral, but only need to know the true strain relation of material true stress. Not only has the accuracy of R6 selection 3 and R6 selection 2 independent of the structure, but also has the advantage of simple calculation method, so the J integral calculation method in this paper has been raised to the practical engineering application level.
【学位授予单位】：华东理工大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH49

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