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  • Summary & Details

Performance Evaluation of Various Structural Damping Materials for Application in Electric Vehicles

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Author(E)1) Oliver Unruh, 2) Bernd Fuhrmann, 3) Heike-Ursula Obst
Affiliation(E)1) Sika Automotive, 2) Sika Automotive, 3) Sika Automotive
Abstract(E)The ongoing electrification of passenger car propulsion systems has an impact on vehicle acoustic quality due to the different excitation characteristics of electrical drives compared to internal combustion engines. The airborne noise and structural vibrations, induced by electric motor, have higher frequency components and they influence the application of acoustic countermeasures in the vehicle. One important element of these treatments is the structural damping package, which can include monolayer damping such as liquid applied sound damping (LASD) as well as bitumen or polymer-based dampers and various multilayer constraint layer damping materials. The performance of damping materials is commonly characterized by the loss factor and estimated by the well-known Oberst Beam Method. Major drawbacks of this method are the measurement limitations to composite loss factors less than 0.3, lower frequency range (less than 500 Hz) and the overall inability to evaluate materials in the excitation frequency range associated with electric propulsion systems. An advanced method called OLF (Optical determination of Loss Factor) is available for material evaluation to much higher frequencies (at least 2 kHz) and allows systematic evaluation of damping material in the specified frequency range. The first part of the paper uses the OLF method to characterize different damping materials regarding their loss factors as a function of frequency and temperature. Additionally, to show the impact of different damping materials on the production car body, a laser vibrometer study is performed. This study shows major differences in vibration attenuation performance of the investigated materials and highlights the importance of accurate selection of suitable damping material for e-vehicles application, all to ensure a high level of acoustic comfort.

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