| With the rapid development of science and the continuous progress of the society, passenger comfort, security, power and green environmental protection is particularly important. Due to the actual strength of bus body is more dependent on the vehicle vibration and random load response. The body design is also converted to the analysis of modal and the dynamic, it abandons the former static analysis of dominant position. So as to make the bus avoid resonance and make a preliminary assessment of dynamic characteristics from body design. In order to accurately predict the reliability and the service life of the body frame, the response of the body structure is researched under the excitation of random road.A full load of bus body frame is taken as the research object in this paper:firstly, the structure of the body frame is analyzed from the structure characteristics, the layout and the load characteristics, etc. Then three-dimensional modeling is established by Solid Works, in order to improve the efficiency and accuracy of the results of finite element analysis, it is necessary to simplify 3D model. Inputting material properties, constraint mode,mesh, the finite element model is generated.Secondly, buses are abstracted into four conditions under stationary and running state of mechanic conditions, according to the actual running situation of bus, the load and boundary conditions of each kind of working situation is defined reasonably. Finite element static analysis is carried out on the bus body frame structure, stress distribution and deformation of bus body is obtained under various working conditions. According to the analysis results, a comprehensive evaluation of the stiffness and strength properties are taken, it provides a reliable theoretical basis for improving the body structure design.Thirdly, based on static analysis, the modal analysis of the bus body frame is carried out by ANSYS Workbench, obtaining its first ten orders natural frequencies and modal shapes, to lay the foundation for the bus body frame toavoid resonance and subsequent dynamic analysis. The vibration amplitude with the change of the excitation frequency curve of body frame structure is obtained by harmonic response analysis, and got the resonance frequency of the body, it provides the basis for improving the design of body frame dynamic optimization and the engine working frequency.Finally, random vibration of the structure of the body frame under random road excitation is conducted by modal superposition method, and stress distribution and displacement deformation for random vibration of the body frame structure is obtained. Using the data from the results of random vibration,and random fatigue strength calculation on the body frame structure is conducted by applying Gauss three interval method and Miner’s law, moreover the fatigue strength of body frame structure under the effect of road random excitation is verified. |
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