起重机提升系统和主梁扭振动力学研究及其多目标优化

发布时间：2018-02-27 23:45

本文关键词： 起重机提升系统动力学主梁扭振多目标优化　出处：《中南大学》2013年博士论文　论文类型：学位论文

【摘要】：起重机是物料搬运行业主要的运输工具,其间歇、重复、循环的工作特点会引起短时、强激励、交变的运行状态,需重点研究其在垂直和扭转方向产生的冲击和振动等动载效应。本文密切结合起重运输机械行业的工程实际需求,提出了多自由度提升系统动力学模型和多段集中质量主梁扭振动力学模型,通过自适应步长四阶Runge-Kutta法进行数值求解,结合现场试验对提升系统和主梁扭振动力学进行了研究及优化分析,研究成果可以为起重机详细设计提供理论依据。主要研究内容与创新点如下： (1)构建了增加自由度的提升系统动力学模型,新增自由度包括：提升钢丝绳时变刚度、减速机构扭转自由度、吊钩以及端梁垂向自由度。基于所建立的系统动力学模型,开发了Simulink求解程序,采用自适应步长四阶Runge-Kutta法高效求解,结果与试验测得的结果吻合,验证了模型的合理性。研究了各种典型工况下提升系统的动力学特性,获取了关键部件在对应工况下的动载系数,为起重机关键零部件设计载荷的选取提供了参考。首次研究了在提升速度一定的情况下,影响提升动载系数的其它因素,为保持起重机运行效率不降低的前提下,进一步减小提升动载系数提供了理论依据。 (2)提出了多段集中质量主梁扭振模型,将主梁扭振问题转化为类传动轴系扭振问题,采用Simulink进行了数值求解,结合现场试验,验证了扭振模型的合理性。研究了吊重离地起升及突然减载工况下的扭振振型和衰减规律,分析了主梁截面、小车对重、吊钩偏心量及小车在主梁上的位置等因素对扭振的影响规律,得到了影响主梁扭振的主要因素,比较了标准工字梁和焊接箱梁扭振特性的差异,为主梁设计时考虑扭振动载及解决主梁因扭振引起的材料失效问题奠定了基础。 (3)建立了综合考虑提升动载和主梁扭转动载等特性的主梁自重多目标优化模型,解决了以往主梁优化仅考虑自重而引起其它部件设计载荷过大的问题。采用本文建立的提升系统和主梁扭振求解模型,以5吨单梁起重机为研究对象,针对吊重离地起升工况进行了全程多目标优化。研究了不同种群规模和进化代数对优化结果的影响,得到了适合于起重机多目标优化的种群规模和进化代数；对计算得到的Pareto非劣解进行了研究分析,结果比单目标优化更为丰富,研究成果已应用在新型主梁设计中；选取不同动态特性参数作为优化目标,研究了多目标优化模型如何选取合理的优化目标。
[Abstract]:Crane is the main means of transportation in material handling industry, its intermittent, repetitive and cyclic work characteristics will cause short-term, strong incentive, alternating operation state, It is necessary to study the impact and vibration effects in the vertical and torsional direction. The dynamic model of multi-degree-of-freedom hoisting system and the torsional vibration dynamic model of multi-segment lumped mass main beam are presented. The numerical solution is carried out by adaptive four-order Runge-Kutta method. Combined with field test, the torsional vibration dynamics of hoisting system and main beam are studied and optimized. The research results can provide theoretical basis for the detailed design of crane. The main research contents and innovations are as follows:. The dynamic model of lifting system with increasing degree of freedom is constructed. The new degree of freedom includes: the time-varying stiffness of wire rope, the torsional freedom of decelerating mechanism, the hoist and the vertical freedom of end beam. The Simulink solution program is developed, and the adaptive step size four-order Runge-Kutta method is used to efficiently solve the problem. The results are in good agreement with the experimental results, and the rationality of the model is verified. The dynamic characteristics of the lifting system under various typical operating conditions are studied. The dynamic load coefficients of the key components under the corresponding working conditions are obtained, which provides a reference for the selection of the design loads of the key parts of the crane. For the first time, other factors affecting the dynamic load coefficient of the crane are studied under the condition of constant lifting speed. It provides a theoretical basis for further reducing the hoisting dynamic load coefficient without decreasing the crane running efficiency. The torsional vibration model of multi-section concentrated mass main beam is put forward. The torsional vibration problem of the main beam is transformed into a torsional vibration problem of a kind of transmission shaft system. The numerical solution is carried out by using Simulink, and combined with the field test, the torsional vibration of the main beam is solved numerically. The rationality of torsional vibration model is verified. The torsional vibration mode and attenuation law are studied under the condition of hoisting and sudden reduction of load, and the cross-section of the main beam and the car counterweight are analyzed. The influence of the eccentricity of hooks and the position of trolley on the main girder is studied. The main factors affecting the torsional vibration of the main girder are obtained, and the difference of torsional vibration characteristics between the standard I-beam and welded box girder is compared. Considering torsional vibration load and solving the material failure problem caused by torsional vibration of the main beam, the foundation is laid for the design of the main beam. (3) A multi-objective optimization model for self-weight of main beam considering the characteristics of lifting dynamic load and torsional dynamic load of main beam is established. This paper solves the problem that the design load of other parts caused by the optimization of the main beam is too large only considering the deadweight. The lifting system and the torsional vibration solution model of the main beam are adopted in this paper, and the 5 ton single beam crane is taken as the research object. The overall multi-objective optimization is carried out for hoisting conditions of hoist hoisting. The effects of different population size and evolutionary algebra on the optimization results are studied, and the population size and evolutionary algebra suitable for crane multi-objective optimization are obtained. The Pareto noninferior solution obtained by calculation is studied and analyzed. The results are more abundant than that of single objective optimization. The research results have been applied to the design of new type main beam, and different dynamic characteristic parameters are chosen as the optimization objective. This paper studies how to select reasonable optimization objectives for multi-objective optimization model.
【学位授予单位】：中南大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH21

【相似文献】