Frequency response function measurements in the presence of non-linear distortions. A general framework and practical advices

In this paper we deal with the measurement of the frequency response function (FRF) of linear dynamic systems in the presence of non-linear distortions. The aim of this paper is to provide the reader insight in the impact of non-linear distortions on FRF measurements. It is shown how to measure the best linear approximation; how to detect, qualify and quantify the non-linear distortions, and this without using additional measurements. Finally, the use of the best linear approximation is illustrated. All results are experimentally verified.