Automotive Engineering - August 2022 - 21

NVH FEATURE
Concept
Reality
From
to
Noise-reduction plot shows the performance of Dow's Betafoam versus the baseline.
the foam material would flow. " When
there are areas of concern, we take that
CAD data and 3D-print the parts long
before release of any sheetmetal. We
don't do any acoustic testing on them.
3D printing has been immensely helpful.
The point is to simply understand how
the material flows through that space.
There are areas within vehicles, both ICE
and EV, that have particular areas needing
to be treated. "
Dow uses a proprietary engineering
methodology called 'Acoustimize' to
evaluate and optimize the NVH performance
of a vehicle as the driver's ear
experiences it. " Acoustimize gives us
the DNA of the vehicle body, " Braun
said. " It tells us how sound travels from
front-to-back, back-to-front, side-toside
and corner-to-corner.
" We measure and introduce noise
throughout certain areas in a microphoned
vehicle that typically has about
32 microphones fitted, " he noted. " We
have six to eight locations where we
introduce noise. "
The Acoustimize process has enabled
Dow engineers to speed development of
robust sound packages for OEMs and
tier suppliers by identifying manufacturing
complexities, such as metal fit, sealer
skips and pass-throughs which are not
detectable by other methods. It also
helps pinpoint noise communication between
different segments of the vehicle.
The company claims that Acoustimize
AUTOMOTIVE ENGINEERING
studies have demonstrated noise-reduction
improvements of five to 20 dB
in applications using Betafoam, compared
to competitive NVH-attenuation
treatments and designs.
Road/tire and wind noise remain an
arch enemy of vehicle development
teams, according to NVH engineers. As
the tire industry investigates a new generation
of non-pneumatic tire tech aimed
at EV applications, new challenges and
opportunities will emerge. Pass-by noise,
initially for European vehicle applications,
also is a focus of NVH material innovations
for the wheelhouse area.
Wind noise is the omnipresent tricky
foe and while incremental noise-reduction
improvements are being made in
this area--vehicle designers would most
like to eliminate exterior mirrors, replacing
them with cameras - OEMs are focusing
on the noise sources (road/tire,
structural vibrations, e-motor frequencies)
on the " lower end " of the body.
As to the future of NVH analysis and
abatement strategies, OEMs increasingly
want to see prediction modeling of foam
behavior in cavities, Braun reported.
" They want us to provide flexibility
and to keep pace with their faster and
faster development cycles, " he said.
" More virtual testing solutions, to supplement
and in some cases replace
physical tests, also are on the way.
OEMs are asking for virtual data more
than ever. "
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August 2022 21
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Automotive Engineering - August 2022

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