Research On The Rigid-Flexible Coupling Impact Dynamics Of Flexible Multibody Systems

In this dissertation, the dynamic modeling theory and numerical simulation for the rigid-flexible coupling impact dynamics of flexible multibody systems are researched.In the particular engineering fields of aviation, aerospace, vehicles, robots, and weapons, there are a lot of contact/impact problems between complex multibody systems. Impact will cause tremendous changes in the dynamical behavior of flexible multibody systems, excite high-order modes of flexible bodies, and affect the operation stability and accuracy of the system. Therefore, impact has become an important factor that cannot be ignored in system analysis and control. Because of the short duration, large intensity, strong nonlinearity, highly coupling, and numerical difficulties of the impact process, the research on flexible multibody impact dynamics has great difficulties. By far, the research is far from maturation. The rigid-flexible coupling impact dynamics of flexible multibody systems has become one of the most challenging research topics in the field of multibody system dynamics.Based on the rigid-flexible coupling dynamic theory of flexible multibody system and the impact dynamic modeling approach, the research on the dynamic modeling theory and numerical simulation for the global rigid-flexible coupling dynamics of flexible multibody systems with impact is presented in this dissertation. Some research work and achievements are as follows:A review of past and recent developments in the multibody system dynamics and the impact dynamics of flexible multibody systems is presented, and the research objectives and the main content of this dissertation are put forward.The impact dynamic modeling theory for a flexible beam with large overall motion is studied. The system’s rigid-flexible coupling dynamic equations without impact are established. The impulse-momentum method, the continuous contact force method, and the contact constraint method are selected to be the impact dynamic approach. The system’s rigid-flexible coupling impact dynamic equations are derived, and the contact/separation criterion is presented. The dynamic transformation and solution are achieved between the impact process and the impact-free process.On the basis of the dynamic modeling theory, the dynamic simulation software for the global dynamics of a flexible beam with large overall motion is developed, and the simulation procedure is given. The impact dynamic simulation examples of the system are presented by using the impulse-momentum method, the continuous contact force method, and the contact constraint method. The dynamic response of the system in the global process is analyzed and contrasted. The characteristics, advantages, defects and application scope of the various impact dynamic approach are compared. Studies shows that the system’s dynamic behaviors change dramatically in the impact process, and the effects of the large overall motion, the small deformation motion and the impact are coupled. The impact makes great effect on the system’s global dynamics during and after impact.The dynamic modeling theory and numerical simulation for the rigid-flexible coupling impact dynamics of multi-link flexible multibody system are studied. The axial, bending, and torsional deformation are all considered. Based on the rigid-flexible coupling theory, the rigid-flexible coupling dynamic equations of the system are proposed, using the recursive Lagrangian dynamic modeling approach. On the use of the impulse-momentum method, the continuous contact force method, and the contact constraint method, the system’s impact dynamic equations are derived. The impact dynamic simulation examples are given to verify the dynamic modeling theory. The dynamic response using various impact dynamic approach is analyzed and contrasted.A partition method for the impact dynamics of flexible multibody system is proposed, based on the rigid-flexible coupling impact dynamic theory for flexible multibody system. The flexible multibody system is divided into the local impact region and the region away from impact, and the two regions are connected by certain boundary conditions. A local impulse method for establishing the initial impact conditions is proposed, which meets the compatibility conditions for contact constraints and the actual physical situation of the flexible bodies’impact process. The system’s rigid-flexible coupling impact dynamic equations are derived based on the contact constraint method. The solving algorithm and several impact dynamic simulation examples are given.Finally, the main research work, achievements and innovations of this dissertation are summarized, and the prospect for further research orientation is presented.