【文章內(nèi)容簡介】
noise. By means of using finite element methods, we can satisfy the requiring of automotive design, and develop the level of design radically. In addition, shortcut the development period and reduce the cost. 1 . Body Structure Static Analysis The key of static analysis is to ensure reasonable loads and their standard. 共 5 頁 第 6 頁 The loads of body structure are very plex. But mostly have two kind like below: (1) Torsion (simulate the wheel run up) the torque can be confirm by axle load , suspension stiffness and the rough of load surface. For minivan it can is equal about . (2) Bending (simulate the weight of passenger and luggage) the load can be ensure according tothe number of passengers and the weight of luggage. The static analysis can be divided into strength analysis and stiffness analysis. For static strength analysis, the safety factor is . For static stiffness analysis, 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 cyl