Complex nonlinear response of a piecewise linear oscillator: Experiment and simulation

In this work an experimental piecewise linear oscillator is presented. This consists of a linear mass-spring-damper undergoing intermittent contact with a slender beam, which can be modelled as providing stiffness support only. Experimental bifurcation diagrams are presented in which a complex response is observed. Smooth bifurcations are recorded, but more typically rapid transitions between at-tractors were observed. All of the following are shown to occur: coexisting attrac-tors, basin erosion associated with grazing trajectories, pairs of unstable periodic orbits, chaotic response, loss of stability through grazing and saddle node bifurcations. All of these come into play to generate the observed experimental bifurcation scenarios. It is shown that a global analysis is important in understanding the system response, especially close to grazing conditions. Although grazing is known to cause a local change in stability, it was found that more often grazing of one orbit would cause a change in the other orbits which resulted in boundary crisis and annihilation of the attractor.