Abstract
The noise of passenger cars must be reduced even further to meet customer requirements. A lower sound level, but also a better sound quality are both aims in making the noise acceptable to passengers. It is therefore desirable that influence of design features on NVH can be predicted as early as possible in the powertrain development plan.
In this paper, a description of a new NVH simulation procedure and analysis is proposed, which can be used in the initial powertrain design and concept phase. The paper outlines the procedure to predict the powertrain structural vibrations and airborne noise, under running conditions, and gives an approach to associate the calculated results with subjective effects inside the car.
The investigation, which uses a new method of analysis, has identified an excitation mechanism for the half-order powertrain vibration, which had not previously been reported. The paper shows simulations which identify and classify the contributions of powertrain stiffness, flywheel dynamics and engine bottom end stiffness to different harmonics.
In this early-stage NVH optimisation procedure, some psychoacoustics criteria related to vehicle interior noise are used to classify the solutions.
Lastly, the paper shows the potential and the role of NVH recommendations in the powertrain design process.