农业工程学报Issue(3)：38-46,9.DOI:10.3969/j.issn.1002-6819.2013.03.006
联合收获机底盘机架有限元模态分析与试验
Finite element mode analysis and experiment of combine harvester chassis
摘要
Abstract
With the rapid development of agricultural mechanization in China, the combine harvester has been applied widely in the past decade. Compared with foreign study, however, domestic studies of the vibration intensity as well as the whole anti-vibration performance of the combine harvester in the various operating conditions were still in its infancy. And few researches were focused on the vibration stability of combine harvester chassis frame, although which was the installed base of the combine harvester, not only carrying the cutter, conveyor, threshing and separating device, but also supporting the engine and other mechanism. During the combine harvester working, the exciting vibrations from the pavement, cutter, engine, vibrating screen and threshing cylinder would cause the combine harvester vibration. Once those excitation frequencies were closed to or overlapped the natural frequencies of the combine harvester chassis frame, the whole body of the combine harvester would produce resonance seriously, which brought about adverse effect on work performance, service life and reliability of the combine harvester. Therefore, in order to improve the operating performance and optimize the chassis structure of the combine harvester, it was particularly necessary to carry out the modal testing and analysis on the chassis frame of the combine harvester. In the paper, the parametric modeling of the combine harvester Julong-280 chassis frame was developed using the three-dimensional modeling software UG. After meshing, the modal parameters as well as the modal vibration shapes were calculated utilizing the NX Nastran, and the first 4 modal frequencies were 20.44, 36.35, 41.75 and 43.67 Hz,respectively. In order to verify the accuracy of the modal analysis results, the laboratory modal testing about the combine harvester JuLong-280 chassis frame was implemented by exciting vibration method with the DH5902 dynamic analysis system. Then experimental modal parameters were obtained, and the first 4 modal frequencies were 20.02, 38.82, 41.02 and 45.78 Hz,respectively. By comparing the above results, it could be seen that the theoretical modal frequencies were close to the experimental modal frequencies (the maximum error is 6.36%) and their mode shapes were also basically the same, which verified the correctness of the calculated results and the accuracy of the chassis frame finite element model. Then, the excitation frequencies of the exciting vibrations from the pavement as well as the engine, cutter bar, vibrating screen and threshing cylinder of the combine harvester were analyzed, and the result demonstrated that the natural frequencies of the combine harvester chassis frame were closed to or overlapped the above excitation frequencies, which implied the combine harvester was vulnerable to resonance in operation. Therefore, in order to improve the modal frequencies to avoid the resonance, a reasonable optimization proposal was conducted by the Altair HyperOpt method. The optimization results indicated that the first 4 modal frequencies of the improved frame increased respectively to 21.70, 36.61, 43.64 and 46.33 Hz with the weight of the frame increased by 3.77%. These values avoided the range of external excitation frequencies of the threshing cylinder 15-18.3 Hz as well as the engine 38.3-41.7 Hz, which means the improvement could avoid the resonance effectively.关键词
联合收获机/模态试验/优化设计/底盘机架/模态分析Key words
combine harvester/modal test/optimization design/chassis/modal analysis分类
农业科技引用本文复制引用
李耀明,孙朋朋,庞靖,徐立章..联合收获机底盘机架有限元模态分析与试验[J].农业工程学报,2013,(3):38-46,9.基金项目
国家科技支撑计划资助项目(2010BAD01B06)、国家"863"计划资助项目(2012AA10A502)、谷物联合收割机多源振动传递机理研究(51205110)、江苏省高校优势学科建设工程资助项目(苏财教(2011)8号)、江苏省农业装备与智能化高技术研究重点实验室开放项目(KF201101)和江苏省农业科技支撑计划资助项目(BE2012382) （2010BAD01B06）
