A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Earth-moving machine cab enclosed sound field active control simulation
Experimental tests carried out inside an earth-moving machine cab enlightened that the noise level at the operator's ear position was higher than 80 dB. The relevant spectrum contained dominant contributions at the first and eighth harmonics of the engine fundamental frequency, due to the engine firing and the cooling system, respectively. Referring to typical machine working conditions and depending on the requested power, the engine rotational speed varies from 1500 r.p.m. to 2500 r.p.m. with a consequent engine fundamental frequency shift from 25 Hz to 40 Hz. The dominant contributions to the global noise level turn out to be always within 400 Hz. in order to have a complete characterisation of the acoustic field in the volume generally occupied by the operator's head, sound pressure maps have been obtained on three vertical parallel planes at a reciprocal distance of 10 cm. Moreover a commercially-available active noise device working as to a single-channel feedforward scheme has been used within the 0-500 Hz frequency range. A first series of experiments has been carried out using the best secondary source positioning on account of practical requirements as implementation facilities and cost minimisation. The results showed noise reductions up to 5-6 dB(A) at the operator's ear position. However the spatial extend of the controlled area and the noise reduction amount strongly depend on the setting of several control parameters like signal amplifications and error microphone position. The present paper reports a first series of results concerning the simulation of the cab enclosed acoustic field. The relevant active noise control achieved by means of the total time-averaged acoustic potential energy minimisation strategy has been emphasized.
Earth-moving machine cab enclosed sound field active control simulation
Experimental tests carried out inside an earth-moving machine cab enlightened that the noise level at the operator's ear position was higher than 80 dB. The relevant spectrum contained dominant contributions at the first and eighth harmonics of the engine fundamental frequency, due to the engine firing and the cooling system, respectively. Referring to typical machine working conditions and depending on the requested power, the engine rotational speed varies from 1500 r.p.m. to 2500 r.p.m. with a consequent engine fundamental frequency shift from 25 Hz to 40 Hz. The dominant contributions to the global noise level turn out to be always within 400 Hz. in order to have a complete characterisation of the acoustic field in the volume generally occupied by the operator's head, sound pressure maps have been obtained on three vertical parallel planes at a reciprocal distance of 10 cm. Moreover a commercially-available active noise device working as to a single-channel feedforward scheme has been used within the 0-500 Hz frequency range. A first series of experiments has been carried out using the best secondary source positioning on account of practical requirements as implementation facilities and cost minimisation. The results showed noise reductions up to 5-6 dB(A) at the operator's ear position. However the spatial extend of the controlled area and the noise reduction amount strongly depend on the setting of several control parameters like signal amplifications and error microphone position. The present paper reports a first series of results concerning the simulation of the cab enclosed acoustic field. The relevant active noise control achieved by means of the total time-averaged acoustic potential energy minimisation strategy has been emphasized.
Earth-moving machine cab enclosed sound field active control simulation
Simulation der aktiven Geräuschminderung im umschlossenen Schallfeld des Führerhauses einer Erdbewegungsmaschine
Carletti, E. (author) / Miccoli, G. (author) / Vecchi, I. (author)
1996
4 Seiten, 1 Bild, 2 Tabellen, 3 Quellen
Conference paper
English
Active Control of Structurally Radiated Sound from an Enclosed Finite Cylinder
| British Library Online Contents | 1994