A frequency-domain approach to crack-related fault detection

Nonlinearity detection and characterization is a hot topic in data-driven engineering or industrial practice. This study theoretically investigates a novel frequency domain method for nonlinearity characterization. It is shown that, with output decomposition and regulation, the even order nonlinearity and crack-incurred nonlinearity (not a simple even order nonlinearity although at its initial stage) can all be effectively evaluated by the magnitude of the 2nd order harmonic response, and the latter is a linear function of the crack severity and can be accurately estimated with the proposed method. The results provide a useful frequency domain approach for nonlinearity detection and characterization.