ON THE HORN EFFECT OF A TYRE/ROAD INTERFACE, PART I: EXPERIMENT AND COMPUTATION

✍ Scribed by R.A.G. GRAF; C.-Y. KUO; A.P. DOWLING; W.R. GRAHAM

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 643 KB
• Volume: 256
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.2001.4238

✦ Synopsis

Near the tyre/road contact area, the road surface and the tyre belt form a horn-like geometry, which provides a signi"cant ampli"cation mechanism for sound sources. Measurements have been carried out on a stationary tyre placed on a plane surface in an otherwise anechoic chamber. Following the reciprocal theorem a microphone was placed in the road surface near the contact patch and a white noise source was used in the far "eld. The ampli"cation by the horn e!ect can then be determined as a function of frequency for an array of microphone positions relative to the contact patch and the centre of the tyre. These experimental measurements show that the horn e!ect is responsible for about 10}20 dB increase in noise level. The ampli"cation function shows a distinct interference pattern for higher frequencies and is independent of the longitudinal source position for low frequencies and source positions close to the contact patch. Numerical calculations using the indirect boundary element method have been carried out. These show excellent agreement with the measurements in the frequency regime of the BEM, i.e., up to 2500 Hz. The dependence of the horn e!ect on primary geometrical parameters such as the e!ect of the radius of curvature of the shoulders, the load and the width of the tyre has been investigated experimentally and numerically. The broad features of the horn e!ect are given by the cylindrical geometry of the tyre. The rounded edges of the tyre tend to increase the levels of the minima and shift them to higher frequencies, while slightly decreasing the levels of the maxima. Shape variations due to load can be accounted for by correcting the source distance to the edge of the formed contact patch. The ampli"cation at low frequencies increases with width, the results collapsing onto a single curve as a function of the dimensionless width / .