A Study On CAE Analysis Of An Integral Articulated Bus

With the rapidly development of our country's public transit, Green Public Transit, Intelligence Public Transit and High-capacity Bus Rapid Transit (BRT) are gradually brought out and used. These new traffic ways extremely improve the technology of our country's city bus. As High-capacity Bus Rapid Transit, the research of low-entry large capacity buses plays very important role. As the vehicles of BRT system, 13.7 meters long large city buses and 18 meters long articulated buses can carry 130 people and 200 people respectively, so they play a very important role in every bus factory's work. At present, almost every bus manufacture has researched their own large capacity buses, during the process of their research, CAE analyses technology are getting more and more used.Using the CAE analyses method can estimate the vehicle in the prime stage of the design process; and it can discover problems at earlier time, shorten the cost of design cycles. At present, more and more advanced CAE technologies are used. As the bringing out of new products becomes more and more quickly, CAE technology has had an indispensable position now. The foreign companies use the FEM(Finite Element Method) to analysis the bus frame's static and dynamic performance which is earlier than china, now have got abundant experiences. Although we've also did many research work in our own country, lots of details need to be studied. At this background, the author did some work on CAE analysis of articulated bus in 18 meters.First of all, this article summarized the main content of the CAE analysis of articulated buses and then described the simplicity fundamental of establishing the CAE model, the method of exerting load and the treatment of constraint in the analysis process, also estimated the static and dynamic performance of the articulated buses. The static analysis mainly indicates the calculation of the bus frame's bending stiffness and torsional rigidity. The evaluation of the bus frame's static stiffness also includes the deformation of the body frame's opening. This article analyzed the body frame's strength condition and stiffness of an articulated bus that studied in our cooperative item; and also calculated the modal analysis, surveyed the dynamic characteristic of the articulated bus. Through this analysis, we discovered that the top bridge of the front suspension may have some design problem, and at the same time more than 52% of all the components have low stress condition. This indicates that the analyzed articulated bus has great lightness vacuum.When we survey the strength of the body frame, we treat the braking case as one special case. Be different with other researchers who directly define the articulated buses'largest braking acceleration as a =μg(μis the ground's largest friction factor, usually a=0.8 ), this article carefully studied the distribution of the braking force. Through the study of 6185 articulated bus, we work out the actual largest braking acceleration—a≈0.65g(g is the acceleration of gravity)of the bus. Then we bring this value into the buses'CAE mode to study the frame's strength condition. Through surveying the distribution of the articulated bus, it can help us to choose the braking system and master the braking efficiency.This article also did many research works on the analysis of the articulation and some important portions. During the initial research, the articulation was simplified as the beam element, this method can't show the details of the stress distribution of body frame. In order to attain more details, this paper modeled the articulation by solid elements and studied the stress distribution of the articulation during the full load high speed cases,full load ascent cases and take turn cases. Through the research we discovered that the articulation is satisfied with the using condition. At the same time the author also give some advices on how to modify the problematical structure that discovered during the analysis process. Considering the structural style and applied forces, this paper decides to move the top bridge 100 millimeters out of their normal position, and changes the structural style of the middle floor, and reduces the dimension of the floor's some middle components. At last, we obtained that the stress of the top bridge is down form 428MPA to 330 MPA and this satisfies the material's using condition.At the end of the article we use the optimum design function of the CAE software to optimize the components with low stress ability of the 6185 articulated bus. Satisfying the integer strength,stiffness and carrying capacity, we did some research on the lightweight work on the side wall of the articulated bus. After optimizing some components with low stress condition, not influencing the integer stress distribution and contorting the modifying component with right stress level, the weight of the articulated bus was cut down 122.3 kilograms. This is an optimistic improvement and if we optimized the whole body frame, the results may be better.