A novel strategy for force identification of nonlinear structures

Abstract

Dynamic force is the key indicator for monitoring the condition of a mechanical product. These mechanical structures always encompass some nonlinear factors. Most previous studies focused on obtaining the dynamic force of linear structures. Consequently, this study focuses on the nonlinear mechanical structure, and a novel identification strategy is proposed to indirectly identify the excitation force. For the identification strategy, based on a nonlinear state-space model, a force identification equation for the nonlinear structure is built, wherein the transfer matrix consists of coefficient matrices of the nonlinear state-space model, and these coefficient matrices are calculated by a nonlinear subspace identification algorithm. Then, under the generalized cross-validation criterion, the truncated total least squares method is introduced to solve the ill-posed equation to eventually obtain the excitation force of the nonlinear structure. The identification results from two numerical simulation cases and one experimental case illustrate that the proposed identification strategy can stably and accurately identify the excitation force of nonlinear structures.

Accelerated generalized minimax-concave sparse regularization for impact force reconstruction and localization

“…To mitigate the highly under-determined and unstable nature of the highly ill-conditioned inverse problem of impact force identification, regularization techniques are commonly utilized. 5 Tikhonov regularization method is one of the classical methods for the inverse problem. Jacquelin et al 6 compared generalized singular value decomposition (GSVD), Tikhonov, and TSVD methods to reconstruct impact forces imposed on an aluminum plate in time domain, and stated that the condition number of the transfer function is influenced by the position of measuring points.…”