Caratterizzazione dinamica non lineare di una cinghia di trasmissione

In this paper the effect of a pulley eccentricity on power transmission belt is experimentally investigated. The evaluation of the nonlinear behaviour of the belt, in presence of large amplitude of vibration due to special resonance conditions, is the goal of the present work. Transversal vibrations of moving surfaces cannot be measured through classical transducers such as accelerometers; therefore in this case Laser displacement transducers are used. An hardening nonlinear behaviour of the system is observed, i.e. the stiffness of the systems grows with the amplitude of vibration. The experimental amplitude-frequency response curve is compared with that of a hardening Duffing oscillator representing the nonlinear vibration when the first mode is directly excited. A parametric resonance phenomenon of subarmonic kind is observed. This is due to the tension fluctuation. The experimental results are explained and compared with those present in literature.