基于有限元和断裂力学的起重机裂纹故障研究

发布时间：2018-01-16 05:25

本文关键词：基于有限元和断裂力学的起重机裂纹故障研究　出处：《武汉科技大学》2012年硕士论文　论文类型：学位论文

【摘要】：起重机是工程实际中的重要设备，随着国民经济的快速发展，它在工程实际中发挥的作用越来越来巨大。与此同时，由于高频率和高负荷的工作，使得起重机故障不断，其中最常见也最危险的是金属结构疲劳裂纹故障，裂纹故障易引发结构破断从而引发重大事故，因此对起重机疲劳裂纹故障的研究成为现代工程中一个重要课题。本文以某公司第三钢轧厂高跨4#125t×22m铸造起重机主梁裂纹为研究对象，以有限元软件ANSYS为研究工具，分析了该起重机疲劳裂纹产生的原因，并提出裂纹止裂修复措施，最后验证了修复的可行性，为起重机同类型裂纹的研究和修复提供了参考。本文所做的主要工作如下：（1）对该起重机主腹板裂纹故障产生的原因进行了分析和研究，利用有限元软件ANSYS分工况对起重机主梁进行了静强度分析，通过分析对比，，发现啃轨力的作用致使主腹板与隔板的焊址处产生较大脉动应力及焊接残余应力过大是主腹板上裂纹产生的两个主要原因。（2）基于线弹性断裂力学对该起重机主梁的疲劳裂纹进行了寿命估算，计算出了含初始缺陷的主梁裂纹扩展设计寿命和该起重机理论使用寿命，并通过计算所得的主梁裂纹扩展剩余寿命得出这些主梁裂纹亟待修补的结论。（3）依据断裂力学裂纹止裂修复理论，提出了主梁裂纹修复措施，并对修复后的主梁再一次进行有限元分析。分析过程采用了ANSYS子模型技术，对裂纹故障部位单独建模分析，使计算效率和精度明显提高。通过修补前后的应力对比分析，得知裂纹位置的应力水平经修补后有了明显下降，且应力水平降至安全范围之内。这个结论验证了笔者采取的修复措施的可行性。（4）结合ANSYS3D断裂模型与子模型技术对裂纹区域进行了模拟，计算出了裂纹尖端的应力水平及应力强度因子幅度Δ K。利用ΔK对修补后的裂纹进行扩展判定和寿命评估，得知裂纹经修复后不会再扩展，从而进一步验证了修补方案的可行性。
[Abstract]:Crane is an important equipment in engineering practice. With the rapid development of national economy, it plays a more and more important role in engineering practice. At the same time, because of high frequency and high load work. The most common and dangerous fault of crane is the fatigue crack fault of metal structure, which can easily lead to structural breakage and lead to serious accident. Therefore, the research on the fatigue crack fault of crane has become an important subject in modern engineering. In this paper, the main beam crack of #4125t 脳 22m foundry crane in the third steel mill of a company is taken as the research object. With the finite element software ANSYS as the research tool, the causes of the fatigue crack in the crane are analyzed, and the crack arrest and repair measures are put forward. Finally, the feasibility of the repair is verified. This paper provides a reference for the study and repair of the same type cracks in cranes. The main work of this paper is as follows: 1) the causes of the main web crack of the crane are analyzed and studied, and the static strength of the crane main girder is analyzed by using the finite element software ANSYS. It is found that the two main causes of cracks on the main web are the large pulsating stress at the welding site of the main web and the excessive welding residual stress due to the action of the gnawing force. Based on the linear elastic fracture mechanics, the fatigue crack life of the main girder of the crane is estimated, and the design life of the crack propagation of the main girder with initial defects and the theoretical service life of the crane are calculated. By calculating the residual life of crack propagation in the main beam, the conclusion that these cracks need to be repaired is obtained. 3) according to the theory of crack stopping and repairing in fracture mechanics, the measures of repairing main beam crack are put forward, and the finite element analysis of the main beam after repairing is carried out again. The ANSYS sub-model technique is used in the analysis process. The calculation efficiency and precision are improved obviously by modeling and analyzing the crack fault location separately. Through the comparative analysis of stress before and after repair, it is known that the stress level of the crack position has obviously decreased after repairing. And the stress level is within the safe range. This conclusion verifies the feasibility of the restoration measures taken by the author. (4) ANSYS3D fracture model and sub-model technique are used to simulate the crack region. The stress level and the amplitude of stress intensity factor 螖 K at the crack tip are calculated. The crack propagation and life evaluation are made by using 螖 K, and it is found that the crack will not propagate after repair. Thus, the feasibility of the repair scheme is further verified.
【学位授予单位】：武汉科技大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH21

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