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The Environmental Protection Agency (EPA) requirement for 54.5mpg by 2025 to reduce greenhouse gases has pushed the industry to look for alternative fuels to run vehicles. Electricity is of those green energies that can help auto industry to achieve those strict requirements. However, the electric or hybrid-electric vehicles brought new challenges into science and engineering world including the Noise and Vibration issues which are usually tied up with both airborne and structural noises. The electromagnetic force plays a significant role in acoustic noise radiation in the electric motor which is an air-gap radial Maxwell force. This paper describes an innovative approach to model the physics of noise radiated by the electric motor.

This paper presents the propshaft liner development that is expanded from previously published SAE technical paper and US patents. The new developments will expand in two facets: liner tuning adjustment and refinement, along with the implications to and solutions for broadband attenuation. Methods for developing a liner with higher tuning adjustment capability will be discussed, along with the results for a design-of-experiments study. In addition, concerns are explored and addressed of broadband attenuation in balancing the tuning effectiveness for particularly targeted frequency range. A particular application of the newly developed liner, trade-marked as Sylent liner, was illustrated and discussed in detail.