Showing papers by "Milena Martarelli published in 2008"

V-belt transverse vibration measurement by means of laser Doppler vibrometry

Abstract: The dynamic behaviour of a power transmission V-belt system with two fixed pulleys has been analysed by applying the theory of the forced non-linear response of a moving string driven harmonically by eccentrically mounted pulleys. The model has been validated experimentally with reference data obtained by measuring out-of plane components of the belt vibration. The experimental data have been acquired by means of a single-point laser Doppler vibrometer (LDV), measuring the transverse vibration of the belt. Another experimentally technique applied here, for transverse vibration acquisition, was the continuous scanning LDV (CSLDV) that has been used for the first time in translating objects. From the model and the measurements, it has been found that the frequency crossing diagrams, analogous to the so-called Campbell plot used in rotating machinery, perfectly agree. Essentially, this plot demonstrates that the natural frequencies are strongly dependent on the belt's transport speed. Consequently, the model can be employed as useful tool for identifying the transport speeds at which resonances are expected.

"dynamic characterization of a washing machine: numerical multi-body analysis and experimental validation"

Abstract: This paper shows the performances of a multi-body model of a washing machine realised with the aim to predict the vibrational behaviour of the whole machine and potentially the acoustic emission. The inputs of the model (pulleys rotation, motor vibrations transmitted via the motor-tube connections) has been measured experimentally at different spin velocities. Each component of the model have been updated by reference test data obtained by performing a modal analysis on the same component excited in controlled conditions. Finally, the model has been calibrated with vibration signals acquired experimentally at different points, i.e. on the tube, on the suspension systems and on the cabinet. The future exploitation of the model will be the employment of its results as the input of an acoustic model (i.e. Boundary Element Method, BEM) in order to calculated the noise generated by the washing machine in operating conditions.