基于XFEM的焊接接头裂尖力学场分析

发布时间：2018-05-20 00:06

本文选题：异种金属焊接接头 + 弹塑性　；参考：《西安科技大学》2017年硕士论文

【摘要】：核电安全端异种金属焊接接头受焊接工艺、材料微观组织结构、几何不连续性和力学性能不均匀性的影响,其焊缝区域的裂纹扩展行为存在不确定性和不规律性。为了给异种金属焊接接头的安全评价提供一定帮助,本文以安全端异种金属焊接接头为研究对象,利用有限元软件ABAQUS中的扩展有限元模块,根据结构的材料力学性能、受力状况及设定的断裂判据确定裂纹的启裂位置及扩展行为,分析了异种金属焊接接头扩展裂纹尖端力学场的分布规律和裂纹扩展路径的特点。完成的主要工作如下:(1)利用有限元软件ABAQUS中的扩展有限元模块,建立了弹塑性条件下异种金属焊接接头材料的裂纹扩展有限元模型,实现了均质材料模型和异种金属焊接接头材料模型的裂纹扩展,提出了扩展有限元法和弹塑性断裂力学相结合的裂纹扩展研究方法;(2)通过建立异种金属焊接接头四种材料的均质模型,分析了不同材料在裂纹扩展过程中的裂尖力学场分布规律和裂纹扩展路径特征,得到了材料抗拉强度、弹性模量和屈服强度变化对扩展裂纹尖端力学场及裂纹扩展路径的影响规律,为研究异种金属焊接接头材料模型的裂纹扩展行为提供参照基准;(3)通过建立异种金属焊接接头材料的裂纹扩展有限元模型,分析了低碳钢A508和316L不锈铡中扩展裂纹尖端的力学场分布规律和裂纹扩展路径特征,得到了抗拉强度、弹性模量和屈服强度失配对扩展裂纹尖端力学场及裂纹扩展路径的影响规律。本文提出的基于扩展有限元在弹塑性条件下的异种金属焊接接头裂纹扩展行为研究方法,为确保核电焊接接头在高温高压水环境下的安全运行具有重要意义。
[Abstract]:Under the influence of welding process, microstructure, geometric discontinuity and non-uniformity of mechanical properties, the crack propagation behavior in the weld zone is uncertain and irregular. In order to provide some help for the safety evaluation of dissimilar metal welded joints, this paper takes the safety end dissimilar metal welded joints as the research object, and makes use of the expanded finite element module in the finite element software ABAQUS, according to the mechanical properties of the materials of the structure. The stress condition and fracture criterion are used to determine the crack initiation position and propagation behavior. The distribution of mechanical field at the crack tip and the characteristics of crack propagation path of dissimilar metal welded joints are analyzed. The main work is as follows: (1) using the expanded finite element module in the finite element software ABAQUS, the crack propagation finite element model of dissimilar metal welded joint under elastoplastic condition is established. The crack propagation of homogeneous material model and dissimilar metal welded joint material model is realized. In this paper, a new method of crack propagation is presented, which combines the extended finite element method and elastic-plastic fracture mechanics. The homogenization model of four kinds of materials for dissimilar metal welded joints is established. The crack tip mechanical field distribution and crack propagation path characteristics of different materials during crack propagation are analyzed, and the tensile strength of the materials is obtained. The influence of the variation of elastic modulus and yield strength on the mechanical field and crack propagation path of propagating crack tip. In order to study the crack growth behavior of dissimilar metal welded joint material model, the finite element model of crack growth of dissimilar metal welded joint material is established. The mechanical field distribution law and crack propagation path characteristics of propagating crack tip in low carbon steel A508 and 316L stainless guillotine are analyzed, and the tensile strength is obtained. The effects of elastic modulus and yield strength on the crack tip mechanical field and crack propagation path are investigated. In this paper, an extended finite element method for studying the crack propagation behavior of dissimilar metal welded joints under elastoplastic conditions is proposed, which is of great significance to ensure the safe operation of nuclear power welded joints under high temperature and high pressure water conditions.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG407

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