Design Of Motorcycle Frame And Its Mechanics Analysis

This thesis focused on the research of the frame and rear fork of the MAX2 motorcycle which is developed in Chongqing Rato Power Co., Ltd. using vibration theory and finite element method. The contents and achievements of this work are as following:The design of the project, layout and frame structural mode is achieved based on the well developed clay model and the exactly 3D digital model for the frame and rear fork was also built.The experiment of modal analysis and modal testing are carried out. Then the exactly meshing process of the frame is preceded with the method of changing the connection type from welding to surface connection. The modal analysis is achieved using Block Lanczos method and the motorcycle's dynamics is primarily evaluated. The model testing of the frame is processed by the LMS testing equipments. Based on the comparison of the testing data, the correctness of the modal analysis is verified and the part which needs modification at the low frequency band is found.The statics of the frame and fork is carried out. The concentrated load is applied by changing the axis of rotation of the frame and fork to MPC multipoint restriction. Through the statics analysis, the parts which beyond the yield limitation on the frame are found and the basis for the design of the spring stiffness is made. The correctness of the design of the spring stiffness of the front and rear damper is verified through the check of the impact loadFrame design is optimized. The design requirements are satisfied by increasing the stiffness which affects the part to improving the inherent frequency of the system based on the modal test and analysis. Based on the statics analysis, the thickness and the structure of corresponding parts were modified to make the parts beyond yield stress meet the request of certain material.