Detection of reduced stiffness in synchronous belts by means of pulley vibration monitoring

This paper discusses a new approach to detecting the detachment of one belt tooth in mechanical transmission systems with synchronous belts, which involves monitoring vibrations in the bodies linked to the pulley. A preliminary numerical analysis was carried out in order to estimate and compare the forces acting on the pulley in a healthy synchronous belt and in a belt lacking one tooth. Simulation results show that the lack of a tooth causes moderate but not negligible variations in the tangential force on the pulley. These variations involve different vibration behaviours that can be studied by analysing vibration signals in the frequency domain. Tests applied using a suitable experimental apparatus confirmed the numerical results. In the power spectrum, the lack of a tooth caused variations in peak amplitudes at multiples of the belt running frequency. In this study, where low frequencies were investigated, the displacement sensor performed better than the accelerometer for vibration measurements.