Study On Key Issues Of Machine Tool Structures Modeling Based On Dynamic Boundary Element Methods

The dynamic characteristics of the machine tool structures should be predicted efficiently in design since they affect the manufacturing quality and productivity. Efficient prediction can improve design quality, reduce trial-manufacture period of innovation product, increase the success rate of once design, and satisfy trial-manufacture requirements of innovation product It is important to enhance the innovation product's advantages in market competition.According to the machine tool structures, its dynamic characteristics depend on all components, corresponding assembled structure and joints of the machine tools. Regarding common plate, beam and corresponding assembled structures as object, dynamic characteristics of the machine tool structures are studied by the dynamic boundary element methods (DBEM).The main contents in the dissertation are as follows:(1) Based on static and dynamic fundamental solutions of the plates, a dynamic modeling method of the plates and the joints are proposed to establish boundary dynamic equations of the plates, by analyzing the procedure of modeling the machine tool structures.(2) Based on dynamic fundamental solutions and static fundamental solutions, boundary dynamic equations of the assembled plate and stiffened plate structures are established by applying rigid conditions. Based on the above equations, the static fundamental solutions in combination with dynamic fundamental solutions are adopted, and boundary dynamic equations of machine tool structures are established by applying flexible joint conditions. A new approach of treating with the joints and modeling the machine tools is presented by ingeniously introducing characteristics of the joints into the whole machine tool.(3) According to the singular integral and the comer questions in calculating the plate structures with dynamic fundamental solutions, the half-analysis separation method for solving the singular integral questions and the corresponding method for processing corner questions are presented.(4) The seeking scanning method for solving the frequency characteristics and an analytical method to calculate modal shapes of the machine tool structures are presented. The established methods have the advantages of fast, simple, easy realization and good robustness. The above methods are effective in computer analysis, which are efficiently used in the machine tool structures with a large number of joints.(5) Based on the proposed analytical approaches for analyzing the dynamic characteristics of the machine tool structures, a series of numerical approaches for analyzing various machine tool structures are formulated and the corresponding analysis program is developed. The validity of the proposed approaches and program are verified by numerical analysis and experiment.