桥式起重机金属结构疲劳损伤和剩余寿命预估研究

发布时间：2018-01-15 18:08

本文关键词：桥式起重机金属结构疲劳损伤和剩余寿命预估研究　出处：《太原科技大学》2011年硕士论文　论文类型：学位论文

【摘要】：随着我国经济的高速发展,作为厂房、冶金、码头等重要的吊装搬运工具,桥式起重机在国民生产中,起着越来越重要的作用。由于生产和生活的需要,起重机经常要在恶劣的环境下连续工作。随之,造成桥式起重机疲劳事故的频繁发生。在这些事故中,最严重也是最常见的一种就是以疲劳裂纹为特征的桥式起重机箱形梁的疲劳破坏。因此,研究疲劳裂纹产生的原因和扩展情况,以及起重机金属结构的剩余寿命,就显的至关重要。对于起重机结构疲劳断裂与剩余寿命的研究,已经有不少的方法;但这些方法要么是停留在理论阶段,要么是模型过于简单;而且在分析手法上,这些研究方法只研究了从变形直至破坏的两种疲劳破坏的极限状态,并未探究这些裂纹形成的原因和深层机理。因此,不能满足安全生产的实际需要。本课题把断裂力学与损伤力学有机地结合起来,对通用的桥式起重机箱形梁加以研究。首先运用有限元分析软件ANSYS,对焊接箱形梁进行典型工况的分析,绘制出相应的应力图和应变位移图,并找出焊接箱形梁上的危险点。其次,把应变片贴在以上分析的桥式起重机的危险部位,采集起重机疲劳载荷数据,接下来运用雨流计数法,对所得的应力—时间历程进行统计计数,得出该台起重机的疲劳载荷谱。再次,对桥式起重机的疲劳机理进行分析,探讨疲劳裂纹的成因。同时,对所产生的疲劳裂纹进行分类,再分别对线弹性裂纹与弹塑性裂纹进行应力强度因子的分析,得出相应的应力强度因子,讨论这些裂纹附近的应力场。由多裂纹迭代法,得出在多裂纹情况下的应力强度因子与多裂纹附近的应力场情况。最后,将断裂力学与损伤力学相结合,推导出桥式起重机焊接箱形梁在恒幅载荷与变幅载荷下的疲劳寿命,同时对于箱形梁上线弹性裂纹与弹塑性裂纹也进行了寿命分析。再结合Visual C++6.0,开发出桥式起重机寿命预估软件,并对实际的起重机,预估其焊接箱形梁的寿命。
[Abstract]:With the rapid development of Chinese economy, as an important lifting and handling tool such as factory building, metallurgy, wharf and so on, bridge crane plays a more and more important role in national production because of the need of production and life. Cranes often have to work continuously in harsh conditions. As a result, bridge crane fatigue accidents occur frequently. In these accidents. The most serious and most common is the fatigue failure of box girder of bridge crane characterized by fatigue crack. Therefore, the cause and propagation of fatigue crack are studied. As well as the remaining life of crane metal structure, it is very important. There are many methods to study the fatigue fracture and residual life of crane structure. But these methods either stay in the theoretical stage or the model is too simple; Moreover, in the analysis technique, these research methods only studied two kinds of fatigue failure limit state from deformation to failure, did not probe into the reason and the deep mechanism of these cracks. Can not meet the actual needs of production safety. In this paper, fracture mechanics and damage mechanics are combined organically to study the box girder of bridge crane. Firstly, the finite element analysis software ANSYS is used. The typical working conditions of welded box beam are analyzed, the corresponding stress diagram and strain displacement diagram are drawn, and the dangerous points on the welded box beam are found. Secondly. The strain gauge is attached to the dangerous part of the bridge crane analyzed above and the data of the crane fatigue load are collected. Then the stress-time history is counted by the rain flow counting method. The fatigue load spectrum of the crane is obtained. Thirdly, the fatigue mechanism of the bridge crane is analyzed, and the causes of fatigue cracks are discussed. At the same time, the fatigue cracks are classified. Then the stress intensity factors of linear elastic cracks and elastic-plastic cracks are analyzed, and the corresponding stress intensity factors are obtained, and the stress fields near these cracks are discussed. The stress intensity factor and the stress field near the multi-crack are obtained. Finally, the fracture mechanics and damage mechanics are combined. The fatigue life of welded box girder of bridge crane under constant amplitude load and variable amplitude load is deduced. At the same time, the life analysis of linear elastic crack and elastic-plastic crack on box girder is also carried out. Combined with Visual C 6.0, the life prediction software of bridge crane is developed, and the actual crane is given. The life of welded box beam is estimated.
【学位授予单位】：太原科技大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH215

【引证文献】