刚柔耦合建模理论的实验验证　

EXPERIMENT VALIDATION ON MODELING THEORY FOR RIGID-FLEXIBLE COUPLING SYSTEMS

传统的混合坐标建模理论是零次近似方法,对刚柔耦合问题的描述存在缺陷.研究以一个由中心刚体、柔性梁及末端质量组成的刚柔耦合系统为对象,建立了精确的一次近似的刚柔耦合动力学方程,在该模型中计及了结构阻尼及风阻的影响.利用单轴气浮台动力学实验平台,通过与实验数据的比较,说明了传统零次近似方法在某些条件下已不能正确描述柔性体的刚柔耦合动力学性质;而一次近似的刚柔耦合动力学模型得到的结果与实验相符,从而验证了一次近似耦合理论的正确性和可靠性.

It's well known that the traditional hybrid-coordinate model of rigid-flexible coupling systems, i.e. the zero-order approximate dynamic model, has some flaws in some high speed cases. The present work presents a finite-element model for a multibody system consists of a rotating hub and a flexible beam with a tip mass on its tip. This theoretical procedure and the traditional hybrid coordinate approach are examined by comparing their numerical simulations with an experimental test. Based on deformation theory and geometric constraints, a second-order approximation for the displacement field is proposed and the dynamic stiffening is accounted for. Since the motion of the hub is unknown, the large overall motion of the reference frame of the beam is not prescribed and is affected by elastic deformation. In order to compare simulation results with experimental data, both viscous damping and air drag force have been introduced into this model. The experiment is carried out in a single-axis air-bearing testbed. The results demonstrate the validity of the developed model, while the traditional hybrid coordinate approach could lead to bad results for some high speed cases.