The Use of the Fitting Time HistoriesMethod to Detect the Nonlinear Behaviour of Laminated Glass

Abstract

The experimental free vibrations of a laminated glass beam are inves- tigated with the aim of extracting the nonlinear characteristics of the dynamical behaviour, by an appropriate post-processing of data en- suing from the tests. An updated version of the Fitting Time History (FTH) technique is used. It is based on the least square approx- imation of the measured damped free vibrations of the laminated glass, and provides the optimal values of the natural frequencies and damping coefficients. While in a previous work attention was mainly devoted to the determination of the linear dynamical properties, here the focus is on the nonlinear behaviour, in particular on the nonlinear relationship between the excitation amplitude and: (i) the natural frequencies, a fact that is commonly encountered in nonlinear dy- namics and known as ‘backbone curve’; (ii) the damping coefficient, a fact that is somehow unexpected and commonly not reported in the literature.