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NVH refinement is an important aspect of the powertrain development and vehicle integration process. The depletion of fossil-based fuels and increase in price of gasoline have prompted most vehicle manufacturers to embrace propulsion technologies with varying degrees and types of hybridization. Many different hybrid vehicle systems are either on the market, or under development, even up to all-electric vehicles. Each hybrid vehicle configuration brings unique NVH challenges that result from a variety of sources. This paper begins with an introductory discussion of hybrid propulsion technologies and associated unique vehicle NVH challenges inherent in the operation of such hybrid vehicles. Following this, the paper outlines a two-dimensional landscape of typical customer vehicle maneuvers mapped against hybrid electric vehicle (HEV) operational modes.

Driveline shudder is a low-frequency (10 Hz - 30 Hz) vibration issue of vehicles that can occur under various test conditions. Specifically, launch shudder is an issue that can be prevalent under vehicle take-off conditions. Factors that typically contribute to launch shudder include stick-slip excitation of friction materials (clutches) and driveline excitations, in particular, on rear wheel drive (RWD) vehicles. Shudder caused by the driveline excitation is generally related to the universal joints (Cardan joints) in the driveline system. In this case, the u-joint forces and kinematics induce a 2nd order excitation when operated under a driveline angle. This document focuses on launch shudder phenomena resulting from driveline system excitation on a RWD vehicle. An initial treatment of the physics governing launch shudder and typical factors influencing the shudder levels in vehicle are provided.

The electrification of vehicle propulsion has caused a significant change in many areas including the world of vehicle acoustics. Comments from the media currently range from “silently hums the future” to “electric car roars with V8 sound”. Decades of experience in designing brand-specific vehicle sound based on noise and vibration generated by combustion engines cannot be simply transferred to the upcoming vehicles driven purely by electric powertrains. Although electric vehicles are almost always considerably quieter than those powered by internal combustion engines, the interior noise is characterized by high-frequency noise components which can be subjectively perceived as annoying and unpleasant. Moreover, such disturbing noise is no longer masked by combustion engine noise. Fundamental questions regarding the sound design of electric vehicles have yet to be answered: it remains unclear what exactly the interior noise of an electric vehicle should sound like.