基于模态置信度准则的插秧机支撑臂模态分析与结构优化

针对高速插秧机栽插机构动力传输过程中的振动问题,该文以2ZG-6DK插秧机为研究对象,分析了栽插系统动力传输方式及工作原理;利用Solid Works软件对插秧机动力传输系统中关键部件支撑臂进行建模,将模型导入ANSYS Workbench并结合Lanczos Method解算方法求解模态固有频率和振型,在此基础上开展基于MAC(modal assurance criterion)准则优化的模态试验,验证了有限元理论分析的准确性。为使支撑臂固有频率避开外部激振频率,在分析外部频率激振特点的基础上,基于ISIGHT多学科软件平台,采用序列二次规划法对支撑臂结构参数进行优化。研究结果表明:优化后支撑臂侧壁腔体厚度5.7 mm、横梁宽度42.0 mm、臂长497.0 mm,前4阶模态频率分别调整至135.17、204.23、483.14和702.32 Hz,均可避开插秧机汽油发动机激振频率范围86.67~120 Hz。优化后1阶频率下振动幅度衰减最为明显,振动幅值最高下降9.4%,支撑臂低频振动特性得到明显改善。研究结果可为插秧机的振动特性分析与减振设计提供参考。

Modal analysis and structure optimization of transplanter support arm based on modal assurance criterion

Abstract: In recent years, with the rapid development of agricultural mechanization in China, rice transplanter has been widely used. Because the transplanting parts of the transplanter have a large vibration in the working process, it will have a great impact on the operation of the machine and the operating environment of the driver. At present, the analysis of the vibration of the support arm of the transplanter and the research on how to reduce the vibration and noise are still in initial stage. In the working process, the support arm bears a variety of dynamic loads, including the working load of various parts, engine and road surface stimulation. When the frequency of the dynamic load is close to the natural frequency of the support arm, the resonance phenomenon will occur. The mechanical resonance affects the normal operation of the transplanter, reduces the service life of the transplater, and seriously affects the comfort of the working environment. Therefore, it is of great of significance to study the vibration and noise reduction of rice transplanter. In view of the vibration and noise problems in the power transmission process of high-speed rice transplanter planting mechanism, 2ZG-6DK rice transplanter was taken as the research object in this paper, and the power transmission mode and working principle of planting system were analyzed. The 3D software was used to standardize the support arm which is the key components in the power transmission system of the transplanter, and the model was imported into the ANSYS Workbench and combined with the Lanczos Method to solve the modal natural frequency and mode shape. In order to optimize the structure of the support arm based on the finite element model, it is necessary to verify the accuracy of the finite element model of the support arm. The modal test of the supporting arm of Nantong 2ZG-6DK transplanter was carried out by using DH5902 Dynamic Data acquisition and modal analysis system, the first 4-order modal frequency and mode of the support arm of the transplanter were obtained by signal analysis and parameter identification. The accuracy of the finite element model of the support arm was verified by the comparison between the modal test results and the finite element analysis results. Based on this, MAC-based (modal assurance) was carried out and the accuracy of finite element analysis was verified. The criterion test optimized the modal test to verify the accuracy of the finite element theory analysis. In order to avoid the external excitation frequency of the support arm, based on the analysis of the external frequency excitation characteristics, and on account of the ISIGHT multidisciplinary software platform, the structural parameters of the support arm were optimized by the sequential quadratic programming method. The results showed that the thickness of the optimized support arm sidewall cavity was 5.7 mm, the beam width was 42.0 mm, the arm length was 497.0 mm, and the first 4-order modal frequencies were adjusted to 135.17, 204.23, 483.14 and 702.32 Hz respectively, which all avoided the gasser engine excitation frequency range 86.67-120 Hz. After the optimization, the vibration amplitude attenuation was the most obvious at the 1-order frequency, the vibration amplitude was decreased by 9.4%, and the low-frequency vibration characteristics of the support arm were significantly improved. The research results can provide reference for the vibration characteristics analysis and vibration reduction design of the rice transplanter.