Article Source: IMechE

As the market for propulsion systems changes to meet consumer needs, engineers working in noise, vibration and harshness are feeling the pressure to use innovative approaches and technologies to measure and analyse vibro-acoustics.

This is a particularly pertinent area of development for automotive NVH engineers, where the market is rapidly becoming less focused on the traditional internal combustion engine. While Automotive OEMs are working to improve fuel economy, reduce emissions, and increase efficiency, this in turn puts more stress on the powertrain system due to higher levels of vibration.

Noise, Vibration and Harshness 22 May 2018

Identifying and addressing issues with NVH as early as possible is important.

“We are constantly trying to understand the system as early as possible, so that should we have a cross attribute conflict, we still have time to change the system,” explained Sean Biggs, Technical Specialist at Jaguar Land Rover.

“If we get it wrong it invariably means a late change which is both costly and stressful.” This view is shared by Professor Stephanos Theodossiades, Professor of Non-Linear Dynamics at Loughborough University, who agreed that “the late development stage that NVH issues come to the surface gives limited time to engineers to react and investigate the root causes of the occurring issues.”

NVH is also a key concern for those developing hybrid and electric vehicles, and automotive engineers are having to adapt to this shift. Furthermore, electric vehicles which do not benefit from the traditional noise of an internal combustion engine and hybrids present a unique challenge when dealing with noise and vibration, from both the internal combustion engine and the electric motor. In this area, Ricardo UK have been developing sound quality requirements:

“Initially this has been a blank canvas” outlined Simon Tate, Ricardo UK’s NVH Department management, “but Sound Augmentation technologies such as Ricardo RAS-R and the ability to develop the acoustics of electric powertrains are providing the tools for exploring the possibilities.”

There are cross industry applications where lessons can be learned, including Targeted Energy Transfer, a method to reduce vibration-induced energy losses, alongside system design, material choice and manufacturing methods. New technologies and approaches are being introduced, including the use of modelling and computer aided engineering to predict noise and vibrations. It particular it is the increased test and CAE integration that Sean Biggs sees as the future for NVH engineering to achieve greater reductions.

“Effective CAE leading (not replacing) the development process will require more detailed testing to develop targets and better understand system performance,” he explained. Other new areas involve the combination of multiple disciplines: “the coupling between dynamics and tribology in NVH and efficiency investigations is a relatively recent trend, which adds more fidelity in the simulation results” said Professor Theodossiades.

“It would be very interesting if manufacturing tolerances and system uncertainties became part of the numerical simulations in order to provide more comprehensive design guidelines.”

With this in mind, the Institution’s upcoming Noise, Vibration and Harshness seminar is well timed to outline the latest developments in this area from the automotive, aerospace, marine, military and power generation industries. Alongside speakers from Jaguar Land Rover, Ricardo UK and Loughborough University, attendees will also hear technical presentations and case studies from specialists at BAE Systems Land, Lloyds Register, Horiba MIRA and Ford Motors amongst others. Join them on 22 May 2018 in Birmingham to understand how your organisation can more effectively meet your vibro-acoustic targets.

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