基于hyperworks汽車車架有限元分析外文翻譯-汽車設(shè)計(存儲版)
【正文】 calculate the torsion loadcase. By our experiences, if the minivan has a very high torsion rigidity, usually it automatically ensures a suitable bending rigidity. Except control the deform value, we must notice the smooth of curve and the deform value of peristome. And it is necessary to analysis the connect stiffness between the body and suspension, engine, body attachment, etc. 2 . The Dynamic Analysis and Evaluation of Body Structure The body in driving endure a lot of excite. Studying dynamic characteristic can effectively analysis automobile fortable, and the fatigue life of body. The aim of studying dynamic characteristic is optimal the body structure and control body mode. The frequency of body must stagger excite frequency. Normally, the first step natural frequency of minivan body is varies between 2040Hz. In the field of the frequency, the source of excite mostly have two kinds: one is the wheel unbalance, frequency varies between 130Hz, the other is engine idle excite, frequency varies between 2040Hz. The excite frequency of wheel can be ensure by driving speed, in China, it is below 150km/h, quite below 21Hz. So the first step natural frequency must above 23Hz. The excite frequency of engine idle lie on the number 共 5 頁 第 7 頁 of cylinders and idle rotate speed. For example: (1) four cylinders, idle rotate speed n = 600r/min, the excite frequency of engine idle: f =(600/60)2=20Hz (2) six cylinders, idle rotate speed n = 600r/min, the excite frequency of engine idle: f =(600/60)3=30Hz (3) eight cylinders, idle rotate speed n = 600r/min, the excite frequency of engine idle: f =(600/60)4=40Hz. The range of body frequency above are body assembly, it is said, body in white add the weight of body attachments, such as seats, doors, engine hood, luggage lid etc. Usually we can simulate those attachments by means of rigid elements, in order to considering their effort. Engine hood and luggage lid must have enough torsional stiffness, doors and their outer panel must have enough stiffness, too. The others, such as mirror, steering system, exhaust, had to have reasonable dynamic characteristic, avoid approach body frequency, in the mean time, must stagger the excite frequency of engine idle, too. TABLE 1. EXCELLENT AGREEMENT BETWEEN THEORY AND EXPERIMENT Analysis result Experime
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