轮胎式起重机底架结构疲劳研究

发布时间：2018-05-14 01:21

本文选题：底架结构 + 疲劳累积损伤理论　；参考：《武汉理工大学》2011年硕士论文

【摘要】：轮胎式起重机采用的是周期性间歇作业,经常会频繁的起升或者下降以及起动和制动。由于其工作速度高,工况复杂而且比较繁重,受循环往复的交变载荷,因而容易产生金属结构件的疲劳开裂,对正常的安全生产造成严重威胁。国内外对起重机的疲劳破坏作了不少研究,但是大多涉及到港口的桥架型起重机,这种类型的起重机通常都没有回转机构,而回转作业会使起重机的作业条件更恶劣,由于产生的应力幅更容易发生疲劳破坏；也有少数涉及到门座式起重机的疲劳研究,但是门座式起重机由于使用了臂架自重平衡系统,可以全幅度变幅和回转作业,而轮胎式起重机只能按照起重能力表在不同的幅度下有其相对的额定起重量。鉴于此,有必要对港口的轮胎式起重机做一个疲劳方面的分析研究。底架是轮胎式起重机的重要的承载结构件,因工况比较繁重以及受力状况复杂而易出现疲劳破坏和裂纹。在以前的轮胎式起重机设计中,主要按照经验设计和静强度设计方法,通常采用选择较大的许用安全系数或者选择提高其材料的许用应力两种办法来减少结构破坏,而这样就必须增加板厚或采用高强度钢,但是这样紧紧是提高了构件的静强度,仍然有可能发生结构疲劳破坏,因为疲劳破坏不同于静力破坏。疲劳裂纹通常是先在结构危险点的局部区域内萌生,然后裂纹扩展直至发生结构断裂。因此,必须采取合理的方法降低危险点的峰值应力,或者提高危险点的局部区域材料强度,才能提高其疲劳强度,从而确保轮胎式起重机安全有效的运行使用。本文首先介绍了疲劳的一些基本概念、疲劳强度理论以及本文所用到的三种有限元分析软件；然后采用MSC.Patran对进行轮胎式起重机底架结构建模,合理分析了载荷情况和加载方式,并对模型局部不断调整,然后使用MSC.Nastran进行静力分析,验算相关的静强度刚度；以《起重机设计规范》为标准,对底架结果进行多种工况下的静力分析结果,按步骤进行疲劳强度校核,发现可能的疲劳点,从而指导设计改正；通过对起重机底架典型工况的瞬态分析得到相关的应力谱,再结合查询得到S-N曲线,利用MSC.Fatigue对底架结构进行了全寿命分析,得出底架结构的全寿命云图,并作出相关分析。
[Abstract]:Tyre cranes use periodic intermittent operations, often frequent hoisting or dropping, starting and braking. Because of its high working speed, complex and heavy working conditions, and subjected to cyclic alternating load, it is easy to produce fatigue cracking of metal structure, which poses a serious threat to normal safety production. Many researches have been done on the fatigue failure of cranes at home and abroad, but most of them involve bridge cranes in ports, which usually do not have rotary mechanism, and rotary operation will make the working conditions of cranes worse. Because the stress amplitude generated is more prone to fatigue failure; there are also a few related to the fatigue study of gantry cranes, but the gantry cranes can vary amplitude and rotate in full amplitude because of the use of the jib self-weight balance system. The tire crane can only have its relative rated lifting weight according to the lifting capacity table at different ranges. In view of this, it is necessary to do a fatigue analysis of the port tire crane. Chassis is an important bearing structure of tire crane. Fatigue failure and crack are easy to occur because of heavy working conditions and complicated mechanical conditions. In the previous design of tire crane, according to the experience design and static strength design method, two methods are usually adopted to reduce the structural damage, such as choosing a larger allowable safety factor or choosing to increase the allowable stress of the material. In this way, the thickness of plate or high strength steel must be increased, but the static strength of the member can be improved so that the fatigue failure of the structure is still possible, because the fatigue failure is different from the static failure. The fatigue crack usually originates in the local region of the dangerous point of the structure, and then the crack propagates until the structure breaks. Therefore, it is necessary to adopt reasonable methods to reduce the peak stress of the dangerous point or to increase the local material strength of the dangerous point in order to improve the fatigue strength and ensure the safe and effective operation of the tyre crane. This paper first introduces some basic concepts of fatigue, fatigue strength theory and three kinds of finite element analysis software used in this paper, and then uses MSC.Patran to model the structure of tire crane chassis, and reasonably analyzes the load situation and loading mode. The model is adjusted locally, and then static analysis is carried out by using MSC.Nastran to calculate the relative static strength stiffness, and the results of static analysis under various working conditions are carried out on the basis of "Crane Design Code" as the standard. The fatigue strength is checked according to the steps, the possible fatigue point is found, and the design correction is guided. The related stress spectrum is obtained by transient analysis of the typical working conditions of the crane chassis, and then the S-N curve is obtained by combining with the query. The whole life of the underframe structure is analyzed by MSC.Fatigue, and the whole life cloud diagram of the underframe structure is obtained, and the correlation analysis is made.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH213.6

【引证文献】