Abstract: The dynamic analysis of flexible hub-beam system is investigated. Firstly, by the Hamilton theory and using the finite element method for discretization, the first-order approximation coupling model and the corresponding KED uncoupled model are presented, respectively. Then dynamic characteristics of the hub-beam system are studied through numerical simulations. Two cases are considered in this study: the rotary inertia of the hub is much larger than or is close to that of the flexible beam. Simulation results demonstrate that there possibly exists failure in using the traditional zeroth-order approximation model for rigid-flexible coupling dynamic system when large motion of the system is unknown, whereas the first-order approximation model is valid. When the rotary inertia of the hub is much larger than that of the beam, the result using the zeroth-order approximation model has small error in comparison with that using the first-order approximation model. But when the rotary inertia of the hub is close to that of the beam, the zeroth-order approximation model may lead to wrong result.

Key words: hub, flexible cantilever beam, zeroth-order approximation model, first-order approximation model, KED uncoupled model