Search Results

In rear wheel drive vehicles, passenger perceived tonal noise is often generated by high frequency rotational vibrations of the transmission output shaft. This rotational vibration is excited by the transmission and couples with the dynamic and inertial properties of the driveline and suspension to generate forces through the suspension attachment locations. This paper demonstrates an approach which uses experimental techniques to measure the rotational dynamics of the output shaft and noise path analysis procedures to predict the vehicle system interaction and resulting vehicle noise contribution from this path. An evaluation of three rotational data acquisition techniques, a measurement technique used to characterize a vehicle's torsional acoustic sensitivity, and an application of mobility coupling to the torsional noise path is presented.

Constrained Layer Damping (CLD) treatments have long provided a means to effectively impart damping to a structure [1, 2 and 3]. Traditionally, CLD treatments are constructed of a very thin polymer layer constrained by a thicker metal layer. Because the adhesion of a thin polymer layer is very sensitive to surface finish, surfaces that a CLD treatment can be effectively applied to have historically been limited to those that are very flat and smooth. New developments in material technology have provided thicker materials that are very effective and less expensive to apply when used as the damping layer in a CLD treatment. This paper documents the effectiveness of such a treatment on a cast aluminum front cover for a V6 engine. Physical construction of the treatment, material properties and design criteria will be discussed. Candidate applications, the assembly process, methods for secondary mechanical fastening will be presented.