Numerical analysis of longitudinal waves in bars for diagnostic purposes

The detection of a local reduction of stiffness in a synchronous belt was experimentally studied by monitoring the vibrations of the support of the driven pulley. The lack of teeth in a synchronous belt is the cause of variations in the forces exchanged between the belt and pulley compared to the forces exchanged in a healthy belt. These variations in force lead to a different vibratory behavior of the bodies of the transmission and can be highlighted by analyzing the vibratory signals. A workbench for the diagnostic study of mechanical transmissions was equipped, and acceleration measurements were performed on the support of the driven pulley under the working conditions of some healthy and defective belts. Comparing the power spectra of the measured accelerations in both cases, meaningful variations in the amplitude of the peaks were observed at frequencies multiple of the frequency of turn of the belt. This result was obtained using some particular test and measurement conditions. A diagnostic procedure for detecting defects in synchronous belts was developed.