Reducing traffic noise and improving comfort in automotive vehicles have been at the core of a recent global initiative. As a result, engineers must comply with strict government regulations while providing a better passengers’ experience. One important requirement involves a measurement procedure referred to as Pass-by Noise: as of recently, the maximum allowed sound level has been reduced, placing a constraint on the design of commercial vehicles. To anticipate the evolution of Pass-by Noise regulations and design vehicles in compliance with future constraints, car manufacturer Renault decided to use MSC’s Actran to extend its acoustic simulation capabilities and model the exterior acoustic propagation.

Improving designs, lowering costs

There are several solutions that engineers have come up with – from adding sound-absorbing materials to modifying parts of the vehicle geometry. But to get off to a truly solid start, Renault decided it needed simulation. “We wanted to have a generic approach valid for any kind of vehicle,” says Philippe Modillat, NVH CAE expert at the Renault Methodology development department. “We needed to have a prediction method for both the acoustic sources and transfer functions from these sources to the regulation microphones.” And that is exactly what the company found in MSC’s solution. Examining noise sources from the engine, the tire-to-road contact, the exhaust line, and the air intake, Renault ultimately succeeded in developing a generic approach for any type of vehicle. Moreover, it is now able to check every vehicle. By considering the vehicle acoustics early in the design phase, Actran has allowed Renault to improve its designs and lower developments costs.

Renault currently uses the methodology on a daily basis to optimize a vehicle’s technical definition, thus ensuring that absorbing materials will be places exactly where needed. “We started from scratch for this exterior acoustic problem, and what we were able to achieve in just a couple of years in this project is quite impressive to me,” Philippe concludes.

Noise is everywhere… have you give it some thought?

Whether it is speakers, kitchen appliances, or vacuum cleaners that you’re producing, have you ever thought about the noise your product might be making? And would you like to optimize it, so your customers will feel better when using it? Then don’t hesitate to contact us. We’d be happy to help!

Dr Michel Azoulay

Upon completion of his PhD in Dynamics and Computational Engineering in Loughborough University in the UK, Michel worked as a simulation engineer in the defense industry for several years.
His extensive consultancy work included multibody dynamics simulation, advanced nonlinear & multiphysics mechanical simulations for defense, aerospace, and transportation industries. Michel is also involved in presales, training, support, and consultancy using MSC Software products for In Summa Innovation customers.