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This study proposes a technique to reduce vehicle longitudinal vibration at surface input without worsening the shock feeling at projection rideover by combining a suspension model with elastic principal axes and a tire longitudinal force model even when the suspension longitudinal rigidity is low. Furthermore, by considering the coupling with the suspension member and the differential gear, and by using the actual tire input characteristics measured in the drum projection test, it is shown that it is possible to reduce vehicle longitudinal vibration at projection ride-over. The intended effects of the numerical simulation were also confirmed by actual driving tests. [ABSTRACT FROM AUTHOR]

This paper addresses the cascading design method of NVH (Noise, Vibration and Harshness) performance between an OEM (Original Equipment Manufacturer) and suppliers. The increasing trend toward electric vehicles requires the exploring of cascading design method, because of the easiness of the assembly of the electric vehicles. However, there are difficulties for the cascading design of NVH performance to overcome the coupling problem among each subsystem. It is generally difficult to divide key evaluation characteristics of a whole structure to individual characteristics of each subsystem because of the coupling resonance. In this paper, cascading design method which utilizes the MMC (Mutual Mean Compliance) was proposed. The MMC is used as an index to meet the final NVH target levels of a whole structure. Then, the MMC is cascaded to each subsystem or component. Finally, the cascaded MMC is achieved by improving individual MMCs of each separate subsystem, while being careful about the resonance of a whole structure caused by strong coupling. In the paper, it is shown that the recalculation of MMCs after subsystem’s structural modification is feasible using FBS (Frequency response function Based Sub-structuring). In addition, MMC based cascading design method using FBS was defined and organized as a procedure. The method was also verified by a numerical case study.