Identification of nonlinear frequency response curves under shaker-structure interaction through force-controller-free phase-locked loop testing

Abstract This paper presents an integrated approach for extracting nonlinear frequency response (NLFR) curves in systems affected by shaker-structure interaction. The approach leverages three distinct phase-locked loop (PLL) testing methods, each tailored for different levels of coupling effects. By resectioning the response surfaces obtained from the proposed PLL-based tests, the need for force controllers is eliminated. The technique is validated through numerical and experimental studies. Experiments conducted on nonlinear beam and plate structures illustrate the effectiveness of the proposed technique, even in the presence of coupled modes.