Spur Gear Vibration Mitigation by Means of Energy Pumping

The dynamic behaviour of a spur gear pair can be studied in terms of transmission error considering a single degree of freedom system. Thus, a mechanical system exhibiting combined parametric excitation and clearance type nonlinearity is examined by means of numerical integrations and continuation methods in an effort to explain its complex behaviour, as it is commonly observed in the steady state forced response of rotating machines. The specific case of a preloaded mechanical oscillator having a periodically time varying stiffness function and subject to a symmetric backlash condition is considered. Even if such an oscillator represents the simplest model able to analyze a single spur gear pair, it exhibits a complex dynamic scenario, namely jumps, superharmonics, subharmonics resonances and dynamic bifurcations. In order to reduce the vibration of the system, a nonlinear absorber is applied. Unlike common linear and weakly nonlinear systems, systems with strongly nonlinear elements are able to react efficiently on the amplitude characteristics of the external forcing in a wide range of frequencies. A strongly and essentially nonlinear, lightweight, with cubic stiffness oscillator is then attached to the main nonlinear system under periodic parametric forcing and the feasibility of a possible application of this nonlinear energy sink (NES) for vibration absorption and mitigation is checked.