At the regular inspection for automobile, an inspector impacts wheel fixing nuts with a hammer and detects the looseness of nuts by listening to impulsive sound. The amplitude of impact force with the impact hammer does not influence the frequency component in the impulsive sound. Excessive impact force only damages the surface of nut. Since several lateral natural frequencies of the wheel are generated for a thin wheel such as the passenger car, the variation of frequency by hammering cannot be detected. It is difficult to detect the looseness of the nut by the spectrum and the wavelet transform analysis for impulsive sound. The purpose of this study is to develop an inspection technique that detects the looseness of wheel fixing nuts easily and quantitatively. The experiments were carried out using an actual passenger car. Effects of the tightening torque of the wheel fixing nut on impulsive sound and acceleration of fixing nut were examined. The variation of frequency in impulsive sound by hammering cannot be detected for the looseness of nut. The impulsive frequency in circumferential acceleration of wheel fixing nut decreases as the tightening torque decreases. Listening to the circumferential vibration of nut by means of sound scope is an easy and accurate inspection technique for looseness of nut.
Acoustical diagnosis for the looseness of wheel fixing nuts of automobile by hammering
Akustische Diagnose der Radmutterlockerung eines Automobils durch Hammerschläge
2001
4 Seiten, 6 Bilder, 1 Quelle
Aufsatz (Konferenz)
Englisch
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