An on-site modal testing method for the detection of structural non-linearities Part I: Development

The work presented in this paper discusses the feasibility of an experimental method to detect non-linear structural behaviour in a practical engineering environment. The method is based on the linear analysis of non-linear systems with increasing amplitude random excitation signals. The analysis of the modal parameters from a linear analysis provides a means to detect when a system is behaving in a non-linear fashion and, under some circumstances, to classify the type of non-linearity present. The basic testing/analysis approach is presented and its characteristics evaluated using data simulating three classical non-linear vibratory systems. The results indicate the method is capable of detecting when these non-linear characteristics become significant to void the use of linear analysis methods. The practical implementation constraints are discussed throughout paper to enable the application of the approach in a more realistic testing environment.