| The farm vehicle which was designed and manufactured by a machinery Co. Ltd ofQinZhou. is mainly used in short-distance transport between urban and rural areas.Because of poor road conditions and driving overloaded. The Farm vehicle find out thatthe frame’s vertical bending deformation is too large; the cab vibration is too large andthe frame’s longitudinal beam break and other questions in the process of using. Thesequestions have affected the normal use of the farm vehicle. To make analysis of thecauses of these problems, and find out a reasonable solution, this paper analyzes thestatic and dynamic characteristics of farm vehicle frame, and finally put forward thestructure improvement scheme of the vehicle frame on the basis of structuraloptimization design.The purpose of this paper is introduce the Computer Aided Design and thefinite-element analysis into the design of the farm vehicle frame to further improve thestructure of the frame design which enable the frame’s structure performance meet therequirements of use. First, before importing the3D model into the finite elementsoftware of HyperWorks，we should reduce the complexity of the vehicle frame structure.Then we should establish the finite element model of farm vehicle with Shell element asthe base unit. The deformation and stress distribution of the frame under different workconditions are gained after static analysis. On the basis of analyzing we find that theframe exists the phenomenon of local stress concentration. And then put forward somefeasible suggestions on the improvement of the frame structure.Secondly, In order to study dynamic characteristics of farm vehicle frame, the freemodal analysis of farm vehicle frame was analyzed by the finite element software ofHyperWorks.At the same time the modal test of vehicle frame is carried out base on theLMS Test LAB vibration test system. We used Least Squares Frequency Domain method(the LSCF method) to extract the modal parameters of farm vehicle frame in theexperiment, and obtained the modal frequency and vibration mode which is almost theconsistent results of finite element software in the range of low frequency. So the resultsof modal experiment proved the correctness of finite element modal. Then by using themulti-body dynamics software MSC.ADAMS to establish rigid-flexible coupling modelof the farm vehicle. Then the simulation of driving on the C and D grade road (whichwere built according to the GB/T7031-2005Mechanical vibration-road surface spectralmeasurement data report) and Washboard road and twist road respectively. Throughdynamic simulation we obtain the dynamic stress curves of the frame in these types ofroad conditions, then we analyze dangerous sections of the frame in the dynamic case,the simulation results are consistent with the actual fracture position of the frame.According to dynamic stress analysis of frame we make more rational structuremodification suggestions for the enterprises and also lay the foundation for the structural optimization.Finally, by using of size optimization method for the key parts of the frame we carryon the modal frequency sensitivity, stiffness sensitivity and Compliance Index sensitivityanalysis. With comprehensive utilization of the result of static, dynamic and sensitivityanalysis,We modify the beam cross-sectional dimension of farm vehicles and carry outthe strength and modal check.In this paper, through analysis of the frame static and dynamic characteristics, weestablish a numerical model and related analysis data of the frame for the enterprise. Atthe same time, we provide the reference for further optimization of the frame structureimprovement and analysis of anti-fatigue characteristic. Such an attempt was valuableboth in academic research and in practical technology. |
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