高超声速飞行器刚体／弹性体耦合动力学建模

高超声速飞行器广泛采用升力体、乘波体等气动布局和轻质复合材料、薄壁结构等,导致结构振动与刚体运动频率非常接近,给飞行器制导控制系统设计带来了巨大挑战.针对该类飞行器的特点,考虑结构的横向位移,将机身前后体简化为于质心处固联的2根悬臂梁,并从统一的能量观点出发,基于拉格朗日方程与虚功原理,在纵向平面推导出适合高超声速飞行器的刚体/弹性体耦合动力学模型.通过对比耦合模型与传统刚体模型的极点分布情况,发现结构振动与刚体短周期模态紧密耦合,离心力的引入影响了高度与长周期模态,对高超声速飞行器航迹运动的作用不可忽视.最后分析了飞行速度与结构阻尼变化对耦合模型动态性能的影响.结果证明飞行速度对刚体运动模态影响显著,而结构阻尼的变化主要改变弹性模态.

Hypersonic vehicle rigid/elastic coupled dynamic modeling

Extensive use of lifting body, wave-rider aerodynamic layout and other composite materials, thin-walled structures, lead the frequency of structural vibration and rigid body motion very close. This yields a great challenge to the vehicle control system design. Taking into account the transverse displacement, a specific simplification which treats the vehicle body as two mass center fixed cantilever beams was adopted. And the hypersonic aircraft-s rigid body/elastic coupling model was derived based on the principle of virtual work and Lagrange equations. After comparing the open-looped poles of new coupling model and traditional rigid body model, a conclusion that the short-period vibration mode and the structures vibration mode tightly coupled with each other was made. The centrifugal force affected the height and long-period mode, and the effect on the flight path can not be ignored. Finally, changes in flight speed and structural damping on the dynamic performance of coupled model were analyzed. Results show that flight speeds significantly affect the rigid body motion modes, while the structural damping mainly changes in elastic mode.