Finite Element Analysis And Test Investigation For XQ6125 City Bus

Model XQ6125 is a city bus designed by our campany which can carry many people. There are some troubles on the bus body frame during our consumers drive the bus. These troubles did not occur during the bus was tried. In order to minutely realize the intensity and rigidity of the bus,so we can drastically resolve these troubles and improve on the design of the bus; in order to pile up the design experience of bus frame with theoretics foundation and in order to master the FEA method of bus; I finished this paper.The contents of this paper includes the application status and development tendency of CAE, the theory basis of finite elements method and finite elements analysis software ANSYS, as well as the finite element emulational and fatigue strength analysis for the typical working conditions of whole framework regarding city bus XQ6125 using software ANSYS based on the statics and dynamics theory, furthermore this paper involves static electromotive test for the bus frame in real multiple working conditions, evaluating the rigidity and strength of city bus XQ6125 from both vision of theory analysis and actual test. The veracity of analysis for real vehicle using finite element model of this bus has been validated according to the data comparison between theoretical analysis and actual measurement.This paper particularly describes the finite element modeling process for the frame of bus body and chassis as a whole and especially the structural statics analysis regarding following working conditions: fully loaded bending condition, the condition when the front left wheel is suspended and the twisting condition when the rear right wheel is suspended. The practical measurement investigation have been carried out for the static bending and twisting working condition of buss body frame in accordance with measurement technology of strain gauge.According to the theoretical analysis and the real measurement results thanks to the strain gauge, it has been proved that the whole structural strength and rigidity of city bus XQ6125 can respect the practical requirement, and generally the rigidity and strength of chassis frame are much stronger than bus body frame. There are some partial areas on the floor frame and three upright poles under waist beam at left rear wheel along with vertical poles of side window after driver window can be found where the stress is biggish when the bus is under fully loaded static twisting conditions, and these areas have some risk.The modal analysis result on the whole structure shows that it is easily to generate resonance phenomenon when frequency activated by engine closes to the intrinsic frequency of the model during the normal idle running of the engine. Furthermore, from the modal analysis we can conclude that chassis frame is not sensitive to the frequency activated by engine in different working conditions, to deal with vibration and noise issue it is proposed to focus more on bus body. It is indicated by the random vibration analysis that the body will generate a strong vibration when the system is under the activation of frequency 9.0283Hz; the top portion of bus body is rather risky when the resonance occurs for the system.The fatigue analysis for the whole structure demonstrates that chassis frame has superior fatigue strength and has no fatigue failure risk; the body frame fatigue strength on front, rear, left, right and top portion of the bus body can meet requirement but it is a little bit lower regarding the fatigue strength on rear floor frame.The comparison that theoretical stress analysis corresponds to the practical measurement results shows the finite element model of XQ6125 is veracious relative to real vehicle. It is trustful regarding the analysis results and the finite element model can be considered as a basis for various mechanics characteristics analysis and study concerning the whole structure of this bus.