工程起重机伸缩臂系统结构稳定性及复合运动动力学研究

发布时间：2018-05-23 13:44

本文选题：工程起重机 + 伸缩臂系统　；参考：《哈尔滨工业大学》2013年博士论文

【摘要】：工程起重机是在一定范围内实现重物水平搬运和垂直提升的多动作起重机械，是各种工程建设中不可或缺的吊装设备。轮式起重机具有机动灵活，稳定性好，效率高，特别适用于狭窄场地作业等优点，被广泛应用于建筑、交通、水电和军工等工程建设中。伸缩臂作为轮式起重机最重要的工作部件，其同时承受较大的轴向载荷和横向载荷，有时还会受到冲击载荷的作用，，为保证其安全可靠的工作，不仅需要进行强度和刚度分析，还需进行准确的动静态稳定性和动力学分析。本文以工程起重机伸缩臂系统为主要研究对象，对起重机伸缩臂系统的动静态稳定问题进行研究，并探讨了支撑油缸、伸缩臂间摩擦力和牵绳或拉索等对伸缩臂起升平面外稳定性的影响。同时，在柔性多体系统动力学基础上，建立一种兼顾精度和求解效率的高效运动弹性动力学分析方法，并针对典型工程起重机柔性伸缩臂系统进行弹性动力学分析。在起重机设计规范GB/T3811-2008中，起重机伸缩臂起升平面外的失稳计算模型为变截面阶梯柱模型，为计算简单起见该模型忽略了内置的支撑油缸和伸缩臂间摩擦力对稳定性的影响。为准确地计入支撑油缸和臂间摩擦力对伸缩臂稳定性的影响，本文在变截面阶梯柱模型的基础上，提出了考虑支撑油缸和同时考虑支撑油缸和臂间摩擦力的两种失稳计算模型。针对不同的失稳计算模型，从精确临界挠曲微分方程出发，分别推导了多节起重机伸缩臂三种失稳计算模型欧拉临界力的递推表达式，并对三种计算模型的欧拉临界力进行了分析比较；此外，还研究了牵绳或拉索等引起的非保向力对伸缩臂起升平面外稳定性的影响。分析结果表明，起重机设计规范中采用变截面阶梯柱模型计算伸缩臂的失稳临界力是偏于安全的，而牵绳或拉索等引起的非保向力能有效地提高伸缩臂起升平面外的抗失稳能力。针对起重机伸缩臂在小变形情况下的动力稳定性问题，通过非线性有限单元法结合Lagrange方程，建立复杂杆系结构在轴向周期载荷作用下的参数振动方程，推导其动力不稳定边界的临界频率方程。应用该频率方程给出了起重机伸缩臂第一和第二动力不稳定区域，并讨论了阻尼对动力不稳定区域的影响，研究结果表明，应用非线性有限单元法求解结构参数振动问题是有效的和精确的；同时随着阻尼的增大，动力不稳定区域减小，且对第二动力不稳定区域影响更加明显。同时，针对传统两结点梁单元在结构稳定分析中精度不够的问题，依据插值理论构造了计及二阶效应的高精度非线性三结点Euler-Bernoulli梁单元，并将该新型梁单元应用于结构动力稳定分析中。该非线性三结点梁单元的计算精度远高于传统两结点梁单元，新型单元与传统梁单元划分3-4个单元时具有相同的计算精度，从而有效地提高求解效率。柔性多体系统动力学方程是一组强耦合、强非线性微分-代数方程组，难以求解和工程实际应用。本文从柔性多体系统动力学理论出发，结合KED方法的特点，采用适当的假设建立了柔性梁杆系统的单元运动方程，给出运动方程中各矩阵的显式表达式，并介绍了集中参数在梁杆任意位置时引起的附加矩阵。同时通过整体坐标系和随动坐标系之间的坐标转化关系矩阵，导出空间梁杆系统在整体坐标下的动力学方程。最后，讨论了动力学方程的求解策略和程序组织，编制了相应柔性梁杆系统动力学分析的数值求解程序。对典型的曲柄滑块机构进行了运动弹性动力学分析，证明了本文高效方法具有较高的分析精度，其计算量与KED方法几乎相当，提高了柔性多体系统动力学方程的求解效率。以QAY500全路面起重机的伸缩臂系统为实例，应用提出的高效柔性系统动力学分析方法，对柔性伸缩臂系统的回转、起升和变幅等复合运动进行动力学分析，考察复合非线性运动过程中柔性伸缩臂系统的动力学响应，给出各关键点或关键构件的变形和内力变化过程，为起重机伸缩臂系统的结构设计分与安全分析提供重要依据。
[Abstract]:The engineering crane is a multi action lifting machine which realizes the horizontal transportation and vertical lifting in a certain range. It is an indispensable hoisting equipment in all kinds of engineering construction. The wheel crane has the advantages of flexibility, stability and high efficiency, especially in the narrow field operation. It is widely used in construction, transportation, hydropower and military workers. As the most important working part of the wheel crane, the telescopic boom is the most important part of the wheel crane. It bears large axial load and lateral load at the same time, and sometimes it will be affected by the impact load. In order to ensure the safety and reliability of the work, it not only needs strength and stiffness analysis, but also needs accurate dynamic and static stability and dynamic analysis. This paper studies the dynamic and static stability of the telescopic boom system of the crane, and discusses the influence of the support oil cylinder, the friction force between the telescopic arms and the rope or cable on the external stability of the telescopic boom. At the same time, a kind of flexible multi-body system dynamics is established. Elastic dynamic analysis of typical engineering crane flexible telescopic boom system is carried out considering the accuracy and efficiency.
In the crane design code GB/T3811-2008, the instability calculation model outside the lifting plane of the crane's telescopic boom is a variable cross section staircase model. For the sake of simplicity, the model ignores the influence of the internal friction force between the supporting oil cylinder and the telescopic arm on the stability. The stability of the support oil cylinder and the arm friction force is accurately calculated for the stability of the telescopic arm. On the basis of the variable cross section column model, this paper presents two models for calculating the instability of the support oil cylinder and considering the friction between the cylinder and the arm at the same time. According to the different instability calculation models, from the exact critical flexure differential equation, three model Eulers are derived for the calculation model of the multi crane telescopic boom. The recurrence formula of the critical force is analyzed and the Euler critical force of the three models is analyzed and compared. In addition, the influence of the non conformal force caused by the rope or cable on the outer stability of the telescopic boom is also studied. The analysis results show that the variable section staircase model is used to calculate the instability of the telescopic boom in the crane design code. The boundary force is partial to safety, and the non directional force caused by the rope or cable can effectively improve the anti buckling ability of the telescopic boom.
In view of the dynamic stability of the crane telescopic boom under the small deformation condition, the nonlinear finite element method combined with the Lagrange equation is used to establish the parametric vibration equation of the complex rod system under the axial periodic load, and the critical frequency equation of the dynamic unstable boundary is derived. The crane telescopic arm is given by using the frequency equation. The first and second dynamic unstable regions have been discussed and the effect of damping on the dynamic unstable region is discussed. The results show that the nonlinear finite element method is effective and accurate in solving the vibration problem of structural parameters, and with the increase of damping, the dynamic instability region is reduced and the influence of the second dynamic unstable region is more evident. At the same time, in view of the problem that the precision of the traditional two node beam element is not enough in the structural stability analysis, the high precision nonlinear three node Euler-Bernoulli beam element with two order effect is constructed according to the interpolation theory, and the new beam element is applied to the structural dynamic stability analysis. The calculation precision of the nonlinear three node beam element is far higher. In the traditional two node beam element, the new element has the same calculation accuracy as the traditional beam element divided into 3-4 elements, thus effectively improving the efficiency of the solution.
The dynamic equation of flexible multibody system is a group of strong coupling and strongly nonlinear differential algebraic equations. It is difficult to solve and apply to engineering. In this paper, based on the dynamics theory of flexible multibody system, combined with the characteristics of KED method, the element motion equation of flexible beam bar system is established with appropriate assumptions, and the matrix of each matrix in the motion equation is given. The explicit expression is presented, and the additional matrix is introduced when the central parameter is at any position of the beam. At the same time, the dynamic equation of the spatial beam bar system in the whole coordinate is derived through the transformation of the relation matrix between the coordinate system and the coordinate system. Finally, the solution strategy and program organization of the dynamic equation are discussed. A numerical solution program for the dynamic analysis of a flexible beam bar system is carried out. The dynamic elastodynamic analysis of a typical crank slider mechanism is carried out. It is proved that the high efficiency method in this paper has high analytical accuracy. The calculation amount is almost equal to that of the KED method, and the efficiency of solving the dynamic equation of flexible multibody system is improved.
Taking the telescopic arm system of QAY500 full road crane as an example, the dynamic analysis method of high efficiency flexible system dynamics is applied to the dynamic analysis of the composite motion of the flexible telescopic boom, lifting and varying amplitude. The dynamic response of the flexible telescopic arm system in the complex nonlinear motion process is investigated, and the key points or key points are given. The process of deformation and internal force changes provides important basis for structural design and safety analysis of crane telescopic boom system.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TH21

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