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Picking up good vibrations

Passenger experience is of paramount importance to the design of any mobility application. Whilst experience can translate into many forms, one of the most pressing is that of acoustic management. As transportation undergoes continuous improvement and adjusts to the needs of the market so too does the requirements of acoustic management methods.

Electric and hybrid vehicles and the rise of noise vibration harshness (NVH)

Conventional combustion engines emit a distinctive pattern of noise and vibration. Over the past century engineers have worked to adequately manage the vehicles acoustics to maximise consumer comfort. As engines have become more effective, so too has the ability to dampen excess sound. Whilst combustion engines provided a challenge for acoustic engineers, the noise and vibration served a purpose. As a vehicle reaches high speeds the components of the vehicle create a selection of buzz, squeaks and rattles which are, in a conventional vehicle mostly drowned out by the sound of the engine. However, in an electric vehicle which creates significantly less noise and vibration the sounds of components rubbing together and rattling against one another can be off-putting. Whilst these sounds are normal and do not present a hazard to the passengers, they can be unsettling and even irritating.

Despite the pandemic the transition to electric and hybrid vehicles continues and in 2020, Europe overtook China as the largest marketplace for these environmentally conscious vehicles. Noise vibration harshness (NVH) has therefore become a major topic for the electric and hybrid vehicles sector. Various methods have been devised to cover up the excess vibrations and sounds from the vehicle including even using speakers to emit noise cancelling background sounds. For the foam and adhesives supply chains this presents an opportunity to offer products which can help to dampen sound and help design engineers (and passengers) avoid a headache. Unlike solid structures, foams and certain adhesives contain gaseous pockets. This structure allows sound to dissipate more effectively than a solid substrate. This is due to the sound waves being slowed down by the soft surface and not simply bouncing off as they would on a solid surface. If components, either as part of the vehicle interior or even structurally, can absorb vibration and sound, the benefit for the EV market can be enormous.

Continuous improvement for the highly regulated aerospace market

Automotive is not the only mobility sector to be examining acoustic management. Aerospace also has an interest in ensuring passenger satisfaction. With much larger engines and greater speeds an aircraft has a sizable challenge in dampening sound successfully. The blessing and the curse of aerospace are twofold, firstly the regulation on aircraft safety features means that the process of qualifying a product takes much longer than it does for the automotive sector. Secondly aerospace has a much larger budget to invest in product development as the stakes are higher. This can prove to be a valuable asset for industries such as automotive who can learn much from the research and development conducted by the aerospace industry.

Not only are the regulations for acoustic management higher for aerospace, the health, safety and lightweighting requirements are also more stringent. A product must be durable, flame retardant and lightweight enough to meet the specifications of the aircraft. The process of acoustic development then becomes about offsetting the mechanical properties of a product in order to meet these needs. Despite being slower moving than the automotive market due to stringent regulation the aerospace market also offers the opportunity for foams and adhesives. As lightweight and sound absorbent materials, their use in the aircraft’s interior and structural components. Adhesives can also act to absorb sound. By using foaming adhesives, engineers are able to absorb sound and lessen the chance of components moving around and causing excess sound. This technology replaces the soft foam used previously and allows for quicker application as well as filling the spaces more effectively. Foam, on the other hand is featured heavily in the aircraft interior and can be further optimised to reduce excess noise.

Acoustic management provides a wealth of opportunity for the foam and adhesives supply chains. Products with the ability to dampen vibration can be highly beneficial to a design team who wish to closely control the experience of the consumer and make it more pleasurable. If cost, durability and lightweighting can be counterbalanced with acoustic development a supplier stands to make themselves invaluable to their customers.