斜接弯管沿管向穿透裂纹弹塑性有限元分析

【作者】 肖传冰；

【导师】 李惠荣；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2003， 硕士

【摘要】 对在役压力管道进行安全评定具有重要的意义。自七十年代至今，断裂力学理论和实际应用都有相当的发展，但是对于目前工程中许多含裂纹结构，进行安全评定所需的可以直接应用的断裂参量解仍很缺乏。本文以断裂力学理论为基础，采用有限元的方法，借助大型通用有限元软件ANSYS分析、计算了工程中常用的焊制斜接四节段弯管斜接管段沿轴向穿透裂纹的线弹性参量K₁因子和弹塑性参量J-积分，给出了其形状系数F和全塑性系数h₁，可供工程实际应用的结论，增补了J-积分全塑性解数据库。包括： 1．建立了焊制斜接四节段弯管有限元模型，分析其在内压、弯矩组合载荷作用下整体应力分布特点，为进一步的断裂分析提供了必要的参考。 2．研究探求ANSYS中含裂纹结构有限元模型建立的方法，根据现有文献的算例验证了裂纹的模拟方法。并以有关斜接弯管的几何、材料、载荷特性等为参数，利用ANSYS提供的参数化设计语言（APDL）编写模型生成程序，用以有限元分析。 3．利用位移法，借助ANSYS后处理器（／POST1），分别在单纯内压、弯矩载荷作用下，求解线弹性断裂参量应力强度因子K₁。并进一步推导得到形状系数F的拟合计算式。 4．处理了ANSYS中非线性材料性质的定义，引入了材料的幂硬化指数n，利用APDL编写了裂纹J-积分求解程序，对本文所述裂纹进行了弹塑性有限元分析。根据EPRI全塑性J-积分处理方法，求解裂纹的全塑性J-积分J_P，裂纹的全塑性解系数h₁。 5．分别计算了内压、按不同比例构成的内压-弯矩组合载荷作用下，裂纹的全塑性解系数h₁，编制了全塑性解系数h₁表格。更多还原

【Abstract】 It is important to give the safety estimation of piping being used. The theories and applicationes of fracture mechanical have developed more since 1970s But,to many structures with cracks being used in engineering, the fracture parameters can be used for safety-estimation are scarce. On the basis of fracture mechanical theory, adopting the technique of finite element analysis(FEA), the study calculated the fracture parameters of stress intensity factor KI and J-integral for the throughwall cracks along the axis of piping elbow with four sections, gived the shape factors F and full-plastic coefficients h1 to supply the datebase of full-plastic solution. Concluding:1. The finite element models of piping elbow with four sections were built, on the basis of the models, the study analyzed the distributions of stress under internal pressure .combined internal pressure and moment to give references for the analysis of fracture.2. Studying the method of building the finite element model for ANSYS program, the study testifid the model on the basis of some known examples. Also, the study compiled the program of creating model in use of a parameter design language(APDL) by the parameters of geometry materials load etc..3. On the basis of the theory of displacement method, the study calculated the linear elastic fracture parameters KI under internal pressure and moment loads through the postprocessor, then, getted the fomulation of shape factor F.4. The study treated with the definition of nonlinear material properties, using the stiffering exponent-n. The program of the solution of J-integral were compiled and the elastic-plastic FEA were done, on the basis of EPRI plastic J-intigral estimation, the full-plastic J-integral and full plastic solution h1 were done.5. The study gived the full plastic solution coefficients h1 under internal pressure and combined internal pressure and moment in different properties.更多还原