关键词: 间隙非线性, 子空间辨识, 非线性翼段, 系统辨识, 条件逆谱法

Abstract: On one hand, it is difficult to establish an accurate dynamical model description reflecting structural characteristics of a real-world complex structure with freeplay nonlinearity because of the inconvenience or impossibility of measuring the gap. On the other hand, even though the freeplay has been estimated, the modal parameters of the nominal linear system of the structure are still out of reach. Therefore, in this paper, nonlinear system identification was performed by the usage of conditioned reverse path method and time-domain nonlinear subspace identification method to obtain the parameters of freeplay nonlinearity as well as the frequency response function of the nominal linear system of the nonlinear structure. A 2-DOF wing section was chosen as a demonstration, on which the numerical experiments of ground vibration tests were performed. Nonlinear system identification was carried out by applying the conditioned reverse path method and time-domain nonlinear subspace identification method. Consequently, the nominal linear system can be accurately estimated by both methods, and the identified parameters of freeplay nonlinearity can also be obtained by smooth function approximation in conditioned reverse path method and by reconstruction via a series of piecewise linear functions in time-domain nonlinear subspace identification method.

Key words: freeplay nonlinearity, subspace identification, nonlinear wing section, system identification, conditioned reverse path method