feasibility study of structural damage detection using narmax modelling and nonlinear output frequency response function based analysis

nonlinear output frequency response functions (nofrfs) are a series of one-dimensional functions of frequency recently proposed by the authors to facilitate the analysis of nonlinear systems in the frequency domain. the present study is concerned with a feasibility study of the application of the well-known nonlinear auto-regressive moving average with exogenous inputs (narmax) modelling method and the nofrfs-based analyses to the detection of damage in engineering structures. the new technique includes three steps. first, a narx model is established by applying the narmax modelling method to input and output data collected from a test on an inspected structure. then, the nofrfs and an associated index for the inspected structure are determined from the established narx model. finally, structural damage detection is conducted by comparing the values of the nofrf index of the inspected structure with the values of the index for a damage-free structure. an experimental application to the detection of damage in aluminium plates demonstrates the potential and effectiveness of the new damage detection technique.