Research On Flexible Body Modeling In Mechanical Dynamics Simulation System

The traditional rigid multi-body system (MBS) dynamics assumes bodies to be rigid. In practice, bodies suffer some degree of deformation. In the majority of the cases the relative displacements are so small that they do not affect the system's behavior. However, in the cases of lightweight spatial structures and manipulators or high-speed machinery, deformation will influence the dynamics of those systems and can not be neglected. This thesis, supported by the National High-Tech, China (No.2004AA411010) and the National Key Science and Technology program (No.2004BA201A85), aims at the implementation of the module of flexible body modeling and simulation and its integration with the original rigid multi-body modeling system, based on the theory of flexible multi-body dynamics and computer graphics.First, a flexible multi-body modeling method, which consists of floating frame of reference and modal superposition is discussed and a modal body formulation is developed. Then the flexible multi-body dynamics formulation is obtained based on the method. The theory of mode analysis and component mode synthesis is discussed. A set of input data for MBS codes describing flexible bodies is proposed and an interface for importing data is designed for the widely used modal neutral file (MNF). The basic model elements and its internal topological relationship are analyzed. Data structure for representing flexible parts is presented. Constraint and force model representation and implementation are developed. After that, the architecture of the multi-body system module is established.Furthermore, the result data of simulation, which is obtained by solving the dynamical model, is reorganized and animation data is built. Combined with computer graphics and computer animation technology, the simulation animation of the model is generated by applying coordinate transformation and view projection on the model.Finally, by using the technologies, a module of flexible body modeling is developed and its integration with InteDyna is implemented on VC++7.0 development platform. A full truck modeling example is presented, which validates that the research and method are feasible and effective.