基于子模型的挖掘机结构瞬态动力学研究

Transient Dynamics Analysis for the Structures of the Excavator Based on Sub-Modeling Method

在挖掘机工作装置结构的瞬态动力学分析中,既要考虑油缸刚度、结构刚度对动态分析的影响,又要考虑得到准确的结构局部(如焊缝)应力用于疲劳分析,如按此要求建立的整体精细模型用于动力学仿真,其工作量是海量的且不现实的.为此,文中提出了整体动态模型与局部子模型相结合的方法,用于挖掘机工作装置结构的动态计算;采用梁单元、弹簧单元等将整体结构等效为一个简单、高效的动态模型;对复杂的局部结构再用精细子模型求解,得到精确局部应力.最后以某型挖掘机为例进行案例计算和试验测试对比分析,计算瞬态应力峰值与测试结果的误差小于8%,结果证明了所提方法和模型的正确性.

In the analysis of transient dynamics of the excavator working device structure,not only the stiffness of both the hydraulic cylinders and the structures,but also the accurate stress of local structures（ such as welded seams） applied in fatigue analysis should be taken into consideration. In order to meet these requirements,a global and refined model should be built for dynamics stimulation,which seems to be overwhelming and impractical.Therefore,a method that combines the global dynamic model with local sub-model is proposed to analyze the structural dynamics of the excavator working device. The global structures are simplified to more simple and efficient dynamic model with beam and spring model. Then,the sub-model with refined finite element is adapted to get the accurate local stress at the complex local structures. Finally,the comparison between the analysis and test results of an excavator shows that the error of the transient stress peak value between the calculation and test is less than 8%.The results show that the proposed method and model is correct.