自由-自由运行体系动态载荷反演问题研究

Study of dynamic force identification for free-free structural system

对自由-自由运行体系动态载荷识别问题进行深入研究,将自由-自由运行体系振动积分方程时域离散化,建立了体系动态载荷反演的力学模型。在动态载荷反演模型求解过程中,由于结构矩阵的病态特性以及测量噪声的影响,常规最小二乘法往往失效;通过对载荷反演模型进行奇异值分解,指出该病态问题的本质,并提出相应的正则化求解方法。数值仿真表明了本文方法能够得到满足工程要求的稳定近似解。本文研究对于实际飞行器运行过程所受动载荷评估具有一定的意义。

A discrete formulation of force identification method in time domain is proposed, which is mainly for reconstructing the dynamics force applied on free-free structural system. The inverse problem of force identification is always ill-posed due to the inverse process of structural matrix and measurement noise in practical engineering and the ordinary least square method always obtains the meaningless solu- tion. This paper further discloses the essence of ill-posedness of force identification problem in detail through the singular valued decomposition technique, and the corresponding regularization technique is presented to single out a stable and useful solution to force identification problem. Finally two forces ex- erting on a free-free plane frame structure are successfully identified by regularization technique with dif- ferent measurement noise, at the same time the force identification results obtained by regularization technique are compared with the results gained by ordinary least square method. The numerical simula- tion shows that the regularized solution to identification of load exerting on the free-free structural sys- tem is valid. The proposed method is meaningful in the application to dynamic force identification for flying vehicles.