Dynamic Analysis Of Mechanical Structure With Finite Wlastic Parts

With the progress of economy and the continuous improvement of the level of science and technology, the development of machanical industry has been an important and powerful driving force. The increase of machanical parts dimension, the decrease of the weight of the structure, the improvement of running speed and the precision of the operation require that both the design and the analysis of the machanical products should be better than ever before. Thus, in order to satisfy the demand of it, the design and analysis method should be more resonable and reliable, which means that part of the crane booms parts are regarded as elastomer and part of them is regarded as the rigid body. Then the crane boom system will be modeled according to the rigid-flexible coupling dynamics. Based on the characteristics of system dynamics equations analyzing the related dynamics, we have the subject about the structual dynamic analysis of the crane with finite elastic parts.The subject is also named the coupled dynamic analysis, this thesis has two parts about the coupled dynamic. One part is that the large rigid displacement will be coupled with small elastic deformation when the kinetic units are modeling. The other part is that part of the units in the system can be regarded as the rigid body, and the other are the flexible one, so the system is a coupled rigid and flexible one which is coupled rigid with flexible body. The characteristic of the paper is when calculating the unit displacement field the traditional first-order linear interpolation theory is discarded. The effect of shear deformation is included into flexural deflection and considering the coupling effects of deformations in the extensional and flexural deflection, the second-order coupling terms of deformations in two displacement fields are developed, so highly accurate displacement field is given.Based on the Lagrange Equation, the article tries to get the unit dynamic equation in the moving coordinate system and apply the derived high precision displacement field in the unit dynamic equation. Then calculate the coefficient matrix in the relevant kinetic equations and verify the coefficient matrix veracity in the high-quality displacement fields. Through changing the coordinate system, we can change the kinetic equation from unit to a whole. After that, according FEM we can build up the kinetic equation of the coupled rigid and flexible system by gathering units and calculate the coefficient matrix in the system dynamics equations.After obtaining the dynamic equations, in terms of solving the dynamic equations, considering the traditional KED methods and flexible multi-body dynamics, to find a calculation method between efficiency and calculation accuracy. First proceed dynamics modeling analysis based on a simple numerical example, then proceed rigid-coupled system dynamics modeling analysis to the crane jib boom system, it will analyze the dynamic characteristics during luffing process, so the method provide a theoretical basis for the structural design of the crane.