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As pressures mount to remove physical prototyping from the vehicle development process, there is a growing need for subjective evaluations of virtual prototypes. Virtually assessing NVH vehicle targets and using driving simulators to make those early critical design decisions is becoming a larger part of the NVH engineering process. Today this is only possible if you put a driving simulator at the center of your development process. Being able to drive and evaluate both test and simulation results simultaneously in a simulator allows engineering teams to leverage a hybrid engineering approach. By starting with measured on-road data from a physical vehicle, engineers can build virtual prototypes. By using this hybrid engineering process to incorporate CAE and test data together an engineer can create a virtual vehicle model with the desired NVH characteristics as a physical vehicle.

As the move to decrease physical prototyping increases the need to virtually prototype vehicles become more critical. Assessing NVH vehicle targets and making critical component level decisions is becoming a larger part of the NVH engineer’s job. To make decisions earlier in the process when prototypes are not available companies need to leverage more both their historical and simulation results. Today this is possible by utilizing a hybrid modelling approach in an NVH Simulator using measured on road, CAE, and test bench data. By starting with measured on road data from a previous generation or comparable vehicle, engineers can build virtual prototypes by using a hybrid modeling approach incorporating CAE and/or test bench data to create the desired NVH characteristics. This enables the creation of a virtual drivable model to assess subjectively the vehicles acoustic targets virtually before a prototype vehicle is available.

Realistically experiencing the sound and vibration data through actually listening to and feeling the data in a full-vehicle NVH simulator remarkably aids the understanding of the NVH phenomena and speeds up the decision-making process. In the case of idle vibration, the sound and vibration of the idle condition are perceived simultaneously, and both need to be accurately reproduced simultaneously in a simulated environment in order to be properly evaluated and understood. In this work, a case is examined in which a perceived idle quality of a vehicle is addressed. In this case, two very similar vehicles, with the same powertrain but somewhat different body structures, are compared. One has a lower subjective idle quality rating than the other, despite the vehicles being so similar.

This work presents an application of airborne source path contribution analysis with emphasis on prediction of wideband sounds inside a cabin from measurements made around a stand-alone engine. The heart of the method is a time domain source path receiver technique wherein the engine surface is modeled as a number of source points. Nearfield microphone measurements and transfer functions are used to quantify the source strengths at these points. This acoustic engine model is then used in combination with source-to-receiver transfer functions to calculate sound levels at other positions, such as at the driver's ear position. When combining all the data, the in-cabin engine sound can be synthesized even before the engine is physically installed into the vehicle. The method has been validated using a powertrain structure artificially excited by several shakers playing band-limited noise so as to produce a complicated vibration pattern on the surface.

The outdoor drive-by test has been part of the standard measurement procedures in the automotive industry for decades. Numerous measurements and publications of results and procedures have focussed on the sound radiation of the moving vehicle and the comparison of results with actual laws and test codes. ISO 362 is the most well known standard which sets the scope of the drive-by method, the instruments, accuracy and the description of the vehicle movement. The noise acceptance limits for various classes of vehicles have been steadily decreasing and will conceivably continue to do so. There is therefore an increasing need for efficient tools to quantify the main sources that contribute to the pass-by noise. A quick method for noise source quantification without having to modify the vehicle e.g. leadwrapping, is highly desirable. Moving source beamforming enables individual noise sources to be quantified at the ISO measurement position during a single pass-by.

For many years engineers in the automotive market have struggled to find ways to accurately and efficiently map the noise sources found inside a vehicle. Many techniques, both theoretical and measurement based, have been proposed and used, but there has always been a trade off between accuracy and efficiency. Techniques like sound intensity mapping and Statistical Energy Analysis have proven to be accurate when mapping noise sources in vehicle, but require a large investment in time and money to create a simple, easy to interpret picture showing where dominant noise sources come from. In this paper the authors will introduce and demonstrate a novel technique, spherical beamforming, which can overcome the issue of test time and produce fast, accurate noise maps from the interior of a vehicle.

An overview is presented of the overpressure and noise due to airbag deployment in a passenger car. Overpressure is the low frequency compression of the air in a closed compartment, and noise is the higher frequency sound of bag inflation. The overview is timely, because there is now an accumulation of medical evidence to indicate that the overpressure and noise resulting from airbag deployment can be a threat to hearing, while, at the same time, the growing use of multiple airbag systems increases the threat. This problem can be counteracted by using aspirating airbags that draw in air from the passenger compartment as they deploy. There are two types of aspirating bag: one using suction that requires a compartmentalized bag and the other using entrainment that does not require a compartmentalized bag. The relative merits of suction and entrainment are discussed in the paper. To date compartmentalized bags have not been used.