This paper presents the key issues to qualify and quantify the shock absorber contribution to the interior noise level of vehicles. Unlike previous papers on suspension noise analysis the shock absorber is investigated as a noise generator rather than a structural noise transmission element. Shock absorber noise can be classified under two types: structure-borne and air-borne noise. Both noise types need a different approach and measuring techniques for both types are discussed. For air-borne noise we discuss the noise measuring environment, equipment and the measurement results from a typical double tube damper. It is explained which parameters cause the scattering of the sound pressure. CFD calculation techniques are used to optimize the hydraulic flow in the damper and consequently to reduce the radiated sound pressure. The simulation of an improvement is tested in practice. Structure-borne noise is investigated by characterising the force output of the shock absorber. The force output of the shock absorber is broad due to the impacts of the different valving combinations inside the shock absorber. A technique how to differentiate the shock absorber noise from the total interior sound pressure level of the vehicle is described. In addition a complete example is elaborated.
Practical techniques for evaluation of structure-borne and air -borne noise of shock absorbers
Praktische Techniken zur Ermittlung des Körperschalls und Luftschalls von Stoßdämpfern
1994
13 Seiten, 16 Bilder, 4 Quellen
Conference paper
English
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