| The industry of motorcycle develops rather late in our country. in the early days of 1980's,the motorcycles were manufactured by introducing overseas 1960's or 1970's technologies and equipment. Most of motorcycle enterprises are still in mapping design phase because of lack of necessary condition and method. It results directly in long period and high cost of researching new products in motorcycle industry .furthermore many problems occurs in the stage of batch manufacture.The frame is the main components of motorcycle , consisting of much kinds of pipe and plate , the room three-dimensional structure being complex frame is as the motorcycle framework. And by the frame motor , drive system and hanging unit , veer unit and wheel and so on consist of an entire one . The frame not merely bear the weight driver, motor and else components , still be able to be subjected to different shocks or liberation. Hence strength and the stiffness design is the significant segment in the frame design.In chapter one, we first summarized motorcycle development history and abroad present situation ,pointing out China is the great state nation of manufacture in the motorcycle at present , yet the level that our country and external have disparity on the motorcycle development catching up in development capability and the manufacture technique ought to be the most pressing matter of the moment . With the development of computer , we can't part from the computer-aided design technique in performance the safe and reliable motorcycle . The finite element method is numerical calculation means adapting to the use calculating machine. Using this method we can calculate displacement field stress field then we use the result improved the composition design as the base. In chapter two, we discuss the method of the finite element m in detail. The fundamental idea is scattered the solution area as one series finite and according to the specified means element that connects together assembly . Since the element compose of the difference mode, and the element in itself may possess not one shape , hence we can model resolution domain of complex geometry shape . Afterwards we detailed introduction the common used beam element in the motorcycle design, pointing out that the beam element is simplifies the frame composition and section property of the element reflect the actual structural property of frame. This kind of method causes to frame analysis calculation more accurately and be able to supple more beneficial help in frame design.We use this method to chapter third , and utilize I-deas finite element analysis software , establishing the frame finite element model , analysis strength and stress distribution of CM125-17's motorcycle frame tianhe-company of Changchun changling. Compare it with the frame experiment. The result show that strongest point of stress appear in the top of strengthen board on back bend beam. So the stress is greet in here ,safety factor is small. In order to improve the bear of the height and the performance of the frame we must ameliorate the frame so that reduce it stress. Hence the 4th chapter optimize CM125-17's motorcycle frame .we have the follow conclusion.1) when building the model , we ought to the entirety be consider model and the appropriate modeling method, accords with the project model to the full and will be convenient for that the calculation is analysed , and hence when establishing finite element model , in order to reveal mechanics characteristic and the smallest solved time we simplify the model. omit some not bearing the weight components , the great model is in the interest of the little model, and decreases amount of work and computation time.2) Using beam element and element partition of the frame and loading means with the focus force and static solution finite element model be able to be overcome else unitary element model. At the same time we verify the model in the way of static load experiment. causing frame analytic system confidence level and operation stren...
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