8Squeak and Rattle Control in Vehicle Body

8.1 Introduction

8.1.1 What Is Squeak and Rattle?

From perspective of noise existing period, the automotive noise can be divided into two categories: continuous noise and transient noise. The continuous noise refers to the noise lasting relative long time or existing all the time, such as engine noise, wind noise. The transient noise refers to the noise coming and then disappearing in a relative short period. The transient noise is an abnormal sound, which should be avoided during vehicle operation.

This chapter focuses on the transient noise of squeak and rattle (S&R). Squeak is generated by the friction between two objects. Rattle is induced by the impact between two objects. In some references, buzz, another transient noise, is included in the scope of squeak and rattle, and they are called BSR.

Buzz is the sound generated by the structural resonance, which is similar to the radiation sound induced by a panel structural resonance. The S&R refers to the sound generated by action between two adjacent parts, while buzz refers to the sound generated from a single part excited by external excitation. Therefore, for most cases, buzz can be separated from the S&R.

Both the S&R and continuous noise are unexpected sounds, but they have differences. In general, the continuous noise is the regular, relatively long duration sound. For example, vehicle occupants can hear regular engine noise during the whole driving period. The engine noise ...

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