重型矿用自卸车车架的模态分析和结构优化

Modal analysis and structure optimization of the frame of heavy mining dump truck

针对国内某重型矿用自卸车车架动静态特性不良的问题,文章建立了车架的有限元模型,并进行了模态分析及测试。结果表明,实验模态和数值计算结果较吻合,且均显示车架的固有频率与电机激励频率重叠。为了改善车架的动静态特性,以静应变能和模态应变能的加权和最小作为优化目标,质量及电机激励频率作为约束条件,通过对各组件板厚特征对加权能和质量的灵敏度分析确定设计变量,对在凸凹路面减速转弯的整车满载车架进行尺寸优化和形貌优化。优化结果表明,车架在质量没有增加的前提下,加权能从8 500J减小到5 600J,车架不再与电机发生共振,且第1阶弹性固有频率由4.93 Hz提高到了6.50 Hz,最大应力从385.9 MPa减小到211.2 MPa,表明车架的动静态特性得到了改善。

In view of the bad static and dynamic characteristics of a domestic heavy mining dump truck , the finite element model of its frame was built and then the modal analysis and test were conducted . The results showed that the experimental results and simulation results were almost identical ,and the frame’s natural frequency overlapped the motor frequency .In order to improve its performance ,the minimized weighted sum of the static strain energy and modal strain energy was taken as the optimization objective ,and the mass and the motor frequency range as the constraint conditions .The design variables were determined according to the results of sensitivity analysis of each component thickness feature related to the weighted energy and mass .The frame’s size and shape optimization design was also done with the whole vehicle under full load condition on the rough road as the vehicle turned the corner with its speed being reduced .The optimization results showed that the dynamic and static characteristics of the frame had been effectively improved .On the premise that the frame mass did not increase ,the weighted energy of the frame reduced from 8 500 J to 5 600 J ;the frame did not resonate with the motor ,and the first‐order elastic natural frequency increased from 4.93 Hz to 6.50 Hz ;and the maximum stress reduced from 385.9 M Pa to 211.2 M Pa .