Force Identification for Nonlinear Structures using the Dynamic Response Sensitivity

Abstract

Force identification is an inverse procedure that estimates the applied forces based on the measured dynamic responses. This paper introduces a novel force identification method for nonlinear finite element models via sensitivity of dynamic response with respect to the load parameters in the time domain. Unlike conventional state space method, the formulation introduced in this study is based on the implicit Newmark method and Newton-Raphson algorithm to solve nonlinear flexible dynamic problems. Since the sensitivities at respective discretized time step are evaluated in geometrically nonlinear framework, robust and accurate prediction of the exciting force in nonlinear problems can be made. In order to demonstrate the effectiveness and validity of the presented method, nonlinear floating beam and 3D shell problems with various loading conditions are provided in this paper. The results show that the proposed method can accurately determine the magnitude of the input forces even with the presence of the noise effect.