农业工程学报
農業工程學報
농업공정학보
Transactions of the Chinese Society of Agricultural Engineering
2015年
19期
46-53
,共8页
姚艳春%杜岳峰%朱忠祥%毛恩荣%宋正河
姚豔春%杜嶽峰%硃忠祥%毛恩榮%宋正河
요염춘%두악봉%주충상%모은영%송정하
农业机械%振动%优化%玉米收获机%车架%模态分析
農業機械%振動%優化%玉米收穫機%車架%模態分析
농업궤계%진동%우화%옥미수획궤%차가%모태분석
agricultural machinery%vibrations%optimization%corn combine harvester%frame%modal analysis
为研究玉米收获机车架振动特性及其优化方法，该文通过振动测试与模态分析方法，分析车架田间振动特性，并以提高1阶扭转频率为目标优化车架结构。首先，通过有限元建模及模态分析，提取车架固有频率与振型，其次，通过整机田间振动试验，获取车架4个测点处振幅统计特征及功率谱，分析其对车架振动特性的影响，最后，研究车架壁厚和刚度与固有频率的关系，以提高车架1阶扭转频率为目标优化车架。研究结果发现，测点振幅大小依次为：车架后桥上方、发动机横梁位置、发动机纵梁位置、车架前桥上方，其中车架后桥上方振幅已超过发动机振幅，发生共振；模态振型与田间振动试验对比发现，1阶扭转和2阶弯曲模态对车架振动影响较大，引起车架共振主频为9.79 Hz，接近1阶扭转共振频率；发现优化后车架1阶扭转振型位移由7.778下降到3.768，1阶弯曲振型位移由6.83下降到3.651，显著改善了车架振型，1阶扭振频率由15.9927提高到22.4595 Hz，提高车架1阶扭转频率。田间耐久试验表明优化后车架无故障时间由20提高到60 h。该研究可为农机装备的振动特性分析与减振设计提供参考。
為研究玉米收穫機車架振動特性及其優化方法，該文通過振動測試與模態分析方法，分析車架田間振動特性，併以提高1階扭轉頻率為目標優化車架結構。首先，通過有限元建模及模態分析，提取車架固有頻率與振型，其次，通過整機田間振動試驗，穫取車架4箇測點處振幅統計特徵及功率譜，分析其對車架振動特性的影響，最後，研究車架壁厚和剛度與固有頻率的關繫，以提高車架1階扭轉頻率為目標優化車架。研究結果髮現，測點振幅大小依次為：車架後橋上方、髮動機橫樑位置、髮動機縱樑位置、車架前橋上方，其中車架後橋上方振幅已超過髮動機振幅，髮生共振；模態振型與田間振動試驗對比髮現，1階扭轉和2階彎麯模態對車架振動影響較大，引起車架共振主頻為9.79 Hz，接近1階扭轉共振頻率；髮現優化後車架1階扭轉振型位移由7.778下降到3.768，1階彎麯振型位移由6.83下降到3.651，顯著改善瞭車架振型，1階扭振頻率由15.9927提高到22.4595 Hz，提高車架1階扭轉頻率。田間耐久試驗錶明優化後車架無故障時間由20提高到60 h。該研究可為農機裝備的振動特性分析與減振設計提供參攷。
위연구옥미수획궤차가진동특성급기우화방법，해문통과진동측시여모태분석방법，분석차가전간진동특성，병이제고1계뉴전빈솔위목표우화차가결구。수선，통과유한원건모급모태분석，제취차가고유빈솔여진형，기차，통과정궤전간진동시험，획취차가4개측점처진폭통계특정급공솔보，분석기대차가진동특성적영향，최후，연구차가벽후화강도여고유빈솔적관계，이제고차가1계뉴전빈솔위목표우화차가。연구결과발현，측점진폭대소의차위：차가후교상방、발동궤횡량위치、발동궤종량위치、차가전교상방，기중차가후교상방진폭이초과발동궤진폭，발생공진；모태진형여전간진동시험대비발현，1계뉴전화2계만곡모태대차가진동영향교대，인기차가공진주빈위9.79 Hz，접근1계뉴전공진빈솔；발현우화후차가1계뉴전진형위이유7.778하강도3.768，1계만곡진형위이유6.83하강도3.651，현저개선료차가진형，1계뉴진빈솔유15.9927제고도22.4595 Hz，제고차가1계뉴전빈솔。전간내구시험표명우화후차가무고장시간유20제고도60 h。해연구가위농궤장비적진동특성분석여감진설계제공삼고。
The low level of Chinese corn harvest seriously has restricted the corn harvest mechanization. Modal analysis is a very important and useful method for various engineering applications, such as design and dynamic test. There are few researches on vibration test and modal analysis of corn combine harvester frame, which is a key part of the corn harvester. During the harvester’s operation, the frame carries and supports the assembly and components, such as engine, cutting header, cab, picking mechanism, elevator, granary, tank, and all alternating loads will eventually pass to the frame. When the vibration frequency is caused by the external excitation and closed to the natural frequency of the frame, it will produce resonance phenomenon, which accelerates the frame strength failure, and therefore affects the dynamic performance and reliability of the frame structure. Using the method of combining the vibration test and modal analysis, this paper studies the vibration characteristics and optimizes the frame, which has the guiding significance for the corn combine harvester design and optimization. Firstly, the paper studies the finite element modeling and analysis method of the frame, and obtains the natural frequency and vibration mode based on the theory of modal analysis. Secondly, using the method of time domain and power spectrum analysis, the paper analyzes the field road test data, and gets amplitude characteristics and power spectrum at 4 measuring points of the frame, as well as attains the excitation frequency of road roughness which is concentrated in the range from 0 to 2.4 Hz, and the whole machine key components’ excitation frequency, and studies the influence of the frame. Eventually, this paper studies the influence of discontinuous change of the interval of frame wall thickness and stiffness on the frequency and mode, improves the first-order frequency based on the fundamental frequency optimization method, and then puts forward the improvement scheme and optimized frame structure. The result shows that the vibration frequency of the rear bridge above the frame is 9.79 Hz, close to first-order resonance frequency, which has caused resonance and strength failure. At the same time, the vibration amplitude of the frame from high to low is as follows: the rear bridge above the frame, the engine beam position, the engine longitudinal beam position, and the front bridge above the frame. The vibration amplitude of the rear bridge above the frame exceeds the engine amplitude, which illustrates the resonance has occurred. After the optimization, the first-order natural frequency of frame keeps away from the external excitation, which increases from 15.9927 to 22.4595 Hz, and at the same time, after the optimization of vibration shape, the first-order torsional eigen mode magnitude decreases from 7.778 to 3.768; the first-order bending eigen mode magnitude decreases from 6.83 to 3.651, which has improved the mode shape. The durability test shows that the failure rate of optimized frame is reduced, and the mean time without failure increases from 20 to 60 h. This paper presents the modeling analysis, vibration test, data processing and structure optimization method, and provides a good reference for corn combine harvester vibration control and performance optimization.
