This article looks at different innovative materials applied to the body structure, their design and their placement to provide a quiet interior of vehicles. A series of vehicle case studies details the in-vehicle performance and benefits of both preformed and bulk material solutions as applied to the body structure: baffles, sealers, barriers, dampers and structural reinforcements. An emphasis is placed on low cost, low mass and high performance optimized solutions. A thorough understanding of the noise source path relationships that exist in the interior of a vehicle has been made available through the use of tools such as Transfer Path Analysis and Airborne Source Quantification. It is known that approximately 85% of the noise entering the passenger compartment of vehicles at frequencies below 500 Hz, enters through structure-borne paths. This changes to approximately 80% contribution through airborne paths at frequencies of 1000 Hz and above. Due to the high contribution of powertrain and road induced noise from the lower body structure, a sealing strategy of the structure-borne paths is employed where baffles or foams are applied to the vehicle to keep these noise components primarily within the lower body. These types of treatments typically are placed at or below the beltline and are intended to keep noise from propagating into the upper car body through its four pillars. Vehicle hollow body cavities are filled either with expandable bulk materials or with preformed materials. The preformed polymer baffles expand and seal the cavity when they are heat reacted by the assembly plant paint ovens. The bulk material is an urethane foam, whose two components quickly mix and form a rigid foam seal in the cavity immediately after injection. In addition to body cavity fillers, barrier plugs and patches are implemented to control noise breakout from body cavities into the vehicle interior. Asphaltic melt sheets constrained layer dampers and a variety of bulk applied sealers are used to minimize panel vibrations and the noise radiation associated with them. Structural reinforcement and recent development of lightweight, expandable structural materials have also improved the overall acoustic performance of production vehicles.
Vehicle acoustics solutions
Schalldämmvorrichtungen in Fahrzeugkarosserien
Sound and Vibration ; 37 , 7 ; 16-19
2003
4 Seiten, 13 Bilder, 1 Tabelle, 8 Quellen
Article (Journal)
English
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