起升载荷下门式起重机主梁损伤与寿命研究

发布时间：2018-05-20 05:47

本文选题：门式起重机 + 主梁　；参考：《辽宁工程技术大学》2015年硕士论文

【摘要】：起重机械对国民经济建设发挥着积极的促进作用,在工作过程中,各机构频繁的完成起动、制动操作,受到正、反向力的交替作用,存在着强烈的振动与冲击,由于经常处于不稳定变幅应力的作用之下,各结构(机构)将产生不同程度的损伤,这直接影响门式起重机的整机性能。主梁作为起重机的关键部件,其损伤情况和寿命在很大程度上决定了起重机的使用寿命。随着我国起重设备制造技术的不断进步与发展,起重机的起重能力、运输距离越来越大,对主梁的安全性要求也越来越高。本学位论文以起升载荷作用下主梁的冲击损伤以及主梁的疲劳寿命为研究对象开展研究,目的在于提高门式起重机主梁的综合性能,为主梁的结构设计提供手段,为门式起重机的安全运行和经济效益的提高提供了一定的理论依据,具有广泛的工程应用背景和一定的学术研究价值。本论文建立了门式起重机主梁结构有限元模型,对其进行了适当简化。采用有限元软件ANSYS Workbench和疲劳分析软件nsoft对主梁的动静态力学特性和疲劳损伤进行了分析。仿真结果表明：主梁受力较大的位置主要集中在主梁的腹板、上下盖板与腹板的焊接部位、横隔板与腹板连接部位以及主梁与支腿连接部位,易产生疲劳损伤；有预应力的模态振频较无预应力模态振频略小,压应力使结构的刚性减少,频率降低;质量的减少会使频率升高；起升时间控制在1-1.5s较为合适,这样既可以保证起重机工作效率,又不会对金属结构和传动部件施加很大的动载荷,从而降低起、制动过程中金属结构的损伤；疲劳损伤是由某几个幅值非常大的循环载荷产生的,40t以上起重量是造成主梁损伤主要载荷；冲击载荷作用下保守估计主梁在不修复的情况下可使用24.7年；过载、残余应力、表面粗糙度和缺口效应均对主梁的使用寿命具有明显的影响。应用以Paris公式和Miner线性损伤理论为基础的疲劳寿命计算数学模型,通过编写MATLAB程序计算门式起重机主梁结构疲劳寿命为24.59年。该寿命计算值与冲击损伤结果较为接近,说明冲击损伤研究具有一定的合理性和科学性。
[Abstract]:Lifting machinery plays a positive role in the construction of national economy. In the process of work, each organization frequently completes the starting and braking operation, is subjected to the alternating action of positive and reverse forces, and has strong vibration and impact. Due to the effect of unstable amplitude stress, various structures (mechanisms) will produce varying degrees of damage, which directly affects the performance of gantry cranes. As the key component of crane, the damage and life of main girder determine the service life of crane to a great extent. With the continuous progress and development of hoisting equipment manufacturing technology in our country, crane lifting capacity, transportation distance is becoming larger and larger, and the safety requirements of the main beam are becoming higher and higher. In this dissertation, the impact damage and fatigue life of the main girder under lifting load are studied. The purpose of this thesis is to improve the comprehensive performance of the main girder of the gantry crane and to provide the means for the structural design of the main girder. It provides a certain theoretical basis for the safe operation of gantry crane and the improvement of economic benefit. It has extensive engineering application background and certain academic research value. In this paper, the finite element model of portal crane girder structure is established, and it is suitably simplified. Finite element software ANSYS Workbench and fatigue analysis software nsoft are used to analyze the dynamic and static mechanical properties and fatigue damage of the main beam. The simulation results show that the main beam is mainly located in the web of the main beam, the welding part between the upper and lower cover plate and the web, the connection part between the transverse diaphragm and the web, and the connection part between the main beam and the supporting leg, which is prone to fatigue damage. The frequency of pre-stressed mode vibration is slightly smaller than that of unprestressed mode, the compression stress reduces the rigidity and frequency of the structure, the reduction of mass increases the frequency, and the lifting time is controlled at 1-1.5 s. This can not only guarantee the efficiency of crane work, but also do not exert great dynamic load on metal structure and transmission parts, thus reducing the damage of metal structure in the process of starting and braking. Fatigue damage is caused by a number of cyclic loads with a very large amplitude. The load of 40 t or more is the main load to cause damage to the main beam, the conservative estimation of the main beam under impact load can be used for 24.7 years without repairing, the overload, the residual stress, The surface roughness and notch effect have obvious influence on the service life of the main beam. The fatigue life calculation mathematical model based on Paris formula and Miner linear damage theory is applied to calculate the fatigue life of gantry crane main girder structure by compiling MATLAB program. The fatigue life of gantry crane main girder structure is 24.59 years. The calculated value of life is close to the result of impact damage, which indicates that the research of impact damage is reasonable and scientific.
【学位授予单位】：辽宁工程技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH213.5

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