Abstract: Identification of impact load on composite material structures is the second-category inverse problem in structural dynamics, prone to significant deviations due to the influence of measurement noise and modeling errors. To address this issue, this paper proposes a novel method for the precise identification of impact load based on truncated vibration responses. Firstly, the complete vibration response is decomposed into multi-scale intrinsic mode functions using variational mode decomposition (VMD), thereby eliminating high-frequency modes and measurement noise to obtain a truncated vibration response that contains only the low-order principal frequency components of the structure. Subsequently, the truncated singular value based least squares method is employed to extract the truncated modal constant vector of the impact location from the truncated vibration response to realize impact localization. Finally, based on the localization results, the collinearity factor of the modal constant vector is estimated, thus completing the inversion of the impact intensity. Experiments on a real wing show that the proposed method can achieve a localization success rate of up to 86.67% by using the truncated vibration response composed of the first three modal acceleration responses of the wing with merely a single accelerometer, and the average peak relative error index of force reconstruction is only 6.51%.

Key words: impact force identification, composite material structures, truncated vibration response, variational mode decomposition, inverse problem