起重机臂架的非线性稳定性分析

发布时间：2018-07-29 20:18

【摘要】：随着工程建设发展的需要,起重机越来越向着大型、高耸、轻柔化、格构式方向发展。由于高强度钢材的大量采用,提高了结构的强度,却使格构式压杆的刚度和稳定性问题日益明显。复杂格构式臂架的稳定性分析已成为大型起重机设计计算的难点。由于履带起重机臂架系统为空间格构式结构,利用传统的数学模型和力学方法已经很难对其稳定性进行准确的校核。因此,必须寻求起重机臂架稳定性的合理分析方法,实现准确计算。针对上述存在的现实问题,本文以某160吨样机为例,在分析起重机臂架的结构特点的基础上,建立臂架的力学模型,并用此模型对臂架的强度和压杆稳定性进行分析,强度和稳定性的最大应力分别432.24MPa和509.7MPa,都小于许用应力510.4MPa,满足强度和压杆稳定性要求,为有限元软件分析提供了参考依据。其次在有限元软件ANSYS中建立了臂架的有限元模型,并对其进行了静态分析,最大应力是430.291MPa,继而进行特征值屈曲分析,以特征值屈曲模态形状作为非线性屈曲分析的初始缺陷,对臂架进行非线性屈曲分析,最大应力是503,828MPa,满足压杆的强度和稳定性要求。将有限元计算结果与起重机设计规范中的公式计算结果进行比较,误差都在2%以下,验证了有限元分析结果的正确性；并分析臂架偏摆力,回转惯性力和风载荷因素对臂架非线性稳定性的影响,由于臂架偏摆力所产生的应力占总应力的32%所以偏摆力是导致臂架失稳的主要因素,在不影响起重机效率的前提下,适当减小回转时的速度和加速度可以提高起重机变截面臂架的稳定性。
[Abstract]:With the development of engineering construction, cranes are more and more large, towering, gentle and lattice. Because of the large use of high strength steel, the strength of the structure is improved, but the stiffness and stability of the lattice compression bar become more and more obvious. The stability analysis of complex lattice boom has become a difficult point in the design and calculation of large crane. Because the boom system of crawler crane is a spatial lattice structure, it is difficult to accurately check the stability of crawler crane by using traditional mathematical model and mechanical method. Therefore, it is necessary to seek a reasonable analysis method for the stability of crane jib to realize accurate calculation. Aiming at the practical problems mentioned above, a 160-ton prototype is taken as an example. Based on the analysis of the structural characteristics of the boom, the mechanical model of the boom is established, and the strength of the boom and the stability of the compression rod are analyzed by the model. The maximum stress of strength and stability is less than that of allowable stress of 510.4 MPa, respectively, 432.24MPa and 509.7 MPa, which meet the requirements of strength and stability of compression bar, and provide a reference for finite element software analysis. Secondly, the finite element model of the boom is established in the finite element software ANSYS, and the maximum stress is 430.291MPa. The eigenvalue buckling analysis is carried out, and the eigenvalue buckling modal shape is used as the initial defect of the nonlinear buckling analysis. The nonlinear buckling analysis of the boom shows that the maximum stress is 503828MPa, which meets the requirements of strength and stability of the compression bar. The results of finite element analysis are compared with those of the formula of crane design code, and the error is less than 2%, which verifies the correctness of finite element analysis, and analyzes the deflection force of boom. The influence of rotary inertia force and wind load factors on the nonlinear stability of the boom. Because the stress produced by the swinging force of the arm frame accounts for 32% of the total stress, the deflection force is the main factor leading to the instability of the boom, without affecting the crane efficiency. The stability of the crane with variable cross section can be improved by decreasing the speed and acceleration of the rotating crane.
【学位授予单位】：东北大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH21

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