Detection and Quantification of Non-Linear Structural Behavior Using Frequency Domain Methods

Most of the practical engineering structures exhibit nonlinearity due to nonlinear dynamic characteristics of structural joints, nonlinear boundary conditions, and nonlinear material properties. In this paper, we investigate the effectiveness of five selected frequency domain techniques for the detection of nonlinear behaviour of the structure. Numerical simulation studies have been carried out by choosing a typical benchmark problem i.e., spring-mass system. The strength and weaknesses of each of the technique are evaluated with respect to their sensitivity to measurement noise. Efforts are also made in this paper to estimate the degree of nonlinearity present in the system using all the five techniques. Numerical investigations are later complemented with experimental studies to demonstrate their practical applicability. The investigations carried out in this paper clearly highlight the effectiveness of the bispectrum technique in robustly identifying the presence and also the degree of nonlinearity in the system.