| 1 | Partition method and experimental validation for impact dynamics of flexible multibody system显示文摘The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications.The numerical approaches being used widely in impact analysis are mainly from two fields: multibody system dynamics(MBS) and computational solid mechanics(CSM).Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed:the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effec-tive formulation considering both accuracy and efficiency.Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion. | J.Y.Wang Z.Y.Liu J.Z.Hong | 2018 | Acta Mechanica Sinica2018，34，3： | 2 |
| 2 | New method for oblique impact dynamics research of a flexible beam with large overall motion considering impact friction force显示文摘A flexible beam with large overall rotating motion impacting with a rigid slope is studied in this paper. The tangential friction force caused by the oblique impact is analyzed. The tangential motion of the system is divided into a stick state and a slip state. The contact constraint model and Coulomb friction model are used respectively to deal with the two states. Based on this hybrid modeling method, dynamic equations of the system, which include all states(before, during, and after the collision)are obtained. Simulation results of a concrete example are compared with the results obtained from two other models: a nontangential friction model and a modified Coulomb model. Differences in the results from the three models are discussed. The tangential friction force cannot be ignored when an oblique impact occurs. In addition, the results obtained from the model proposed in this paper are more consistent with real movement. | W.Yuan L.Li D.G.Zhang J.Z.Hong | 2016 | Acta Mechanica Sinica2016，32，4： | 1 |
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