Celebrating

125yearsVol. 200 • Issue 1

ai-online.com • autoindustry.us • peace

A GUIDE TO THE

digitization

OF MANUFACTURING

AUTOMOTIVE INPUT
pricing systems disrupted
by tech companies
PMMA COMPOUNDS
enable the reshaping ofvehicle front-ends

Controlling noise levels
in electric vehicles

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visit ai.com.ai“Lightweight multilayer products are required to build
lighter vehicles without compromising acoustic comfort.
Sika follows a very straight forward philosophy: the rightmaterial with the right design at the right place.”– Bernd Fuhrmann. Global Product Manager Damping & Head of Acoustic Center, Sika Automotive.

“damping properties than lower performing damping
Some Sika solutions have up to four times higherinnovationmaterials such as monolayer, magnetic bitumen or”

sprayable products of comparable weight.

“Quiet” electric vehicles spark
new noise challenges
By: Tony Davidson

New energy vehicles (NEV) present a range of new design challenges for developers andsuppliers of noise damping materials and solutions.

Optical determination of Loss Factor (OLF) in the Sika
Acoustic Center.

Composite loss factor performance of the SikaDamp-641
constrained layer damper.

Lightweight multilayer products are required to build lighter vehicles
without compromising acoustic comfort. Noises such as road-tireinteraction, which is largely muffled by internal combustion engines,
become much more intrusive in a quiet, electrically powered car.
New composite materials and manufacturing techniques
used in electric vehicles also introduce their own frequencies ofstructure-borne noises. One of the companies in the technologicallead in this field is Sika, which has won multiple awards from
OEMs for the quality and consistency of its products.
Automotive Industries (AI) asked Bernd Fuhrmann.
Global Product Manager Damping & Head of Acoustic
Center, Sika Automotive, to outline some of the specificchallenges in damping electric vehicle noise.
Fuhrmann: The excitation characteristic shifts from the lowfrequency combustion sounds of the internal combustion engine(ICE) to specific noise and vibration signature of the electric motor.
Road and wind noise is not affected, but high-frequency vibration
sources from the electrical system and drivetrain become more
prominent, especially in the critical frequency range between 500
Hz and 2500 Hz.

Additionally, the integration of the batteries as a vital
structural component of car body design increases the overall
body stiffness. The change shifts the structural resonancefrequencies, which are higher than those of conventional ICE
body design, hence the acoustic materials must be engineered
to address this change.
AI: What products has Sika developed for electricvehicles?
Fuhrmann: Sika has developed multi-layer damping systems
to address a wide frequency range. Some Sika solutions have up
to four times higher damping properties than lower performingdamping materials such as monolayer, magnetic bitumen orsprayable products of comparable weight.
One aspect of electric vehicles that is often overlooked isthat they tend to be heavier than their conventionally poweredcounterparts, mainly due to the weight of the battery system.
When implementing damping solutions, low weight options
should be considered in order to lower overall vehicle mass andease range issue. Within Sika damping portfolio, there are very low
weight systems such as SikaDamp-760 Ultralight, which provides

2TO READ THE FULL VERSION OF

STORIES GO TO www.ai-online.com

twice as much damping performance at 25% of the weight whencompared to monolayer damper with similar performance.
AI: How important is it to target noise as close to thesource as possible?
Fuhrmann: At Sika we believe that it is the most efficient andleast expensive approach to reduce interior noise. The vehicle
body itself is the biggest radiator of airborne noise in the vehicle.
When more vibrational energy is input to vehicle body, more
airborne noise will be radiated.
Highly effective damping solutions can greatly attenuate thevibrational energy leading to the lower airborne noise. Conversely
if one chooses to use low performing damping materials or
minimalistic damping packages, the resulting increased level ofairborne noise will have to be countered with more interior NVH
measures such as heavy carpet layers with thick foam absorbers
or synthetic fleeces. These treatments would add additional
weight and cost to the vehicle.
AI: Are your solutions saving weight?
Fuhrmann: Sika has a wide range of damping products
within its portfolio. SikaDamp high performance constrained

design at the right place. We design parts to avoid oversizedlayouts and to further reduce weight while addressing vibrational
hotspots with appropriate material choice. Compared to thesprayable damper which is very limited in scaling performance,
our approach opens a versatile and flexible layout of theacoustical damping package.
AI: What research and development and testing backyour products?
Fuhrmann: The Sika development process incorporates
various methods and tools for characterizing and quantifying
material properties including mechanical and acousticalcharacteristics. We can respond in all customer regions, backedby R&D centers located all over the world, to meet customer
specifications, regulatory requirements and sustainability targets.
With a focus on holistic material characterization, Sika has also
developed a method for measuring high frequency performanceof the products, enabling us to compare acoustical performanceon a much more detailed level.
AI: What is the Optical determination of Loss Factor (OLF)?
Fuhrmann: The OLF method was developed by Sika inPlacement and shape of parts can be highly
tuned through laser-vibrometer analysisof the entire body panel system, whichallows for targeted, cost-efficient use, whileachieving maximum damping effect.

layer damping (CLD) system is engineered to reduce the overall
damping package weight while significantly increasing acoustic
performance. Consequently, there is a potential to double theweight saving.
First, one can replace the conventional monolayer damping
systems one-to-one with the CLD systems where weightsaving of up to 50% is possible. Second, with the higher
performance of the CLDs, it is theoretically possible to redesign the damping package to reduce material usage andstill accomplish the same overall acoustic performance.
Besides the material approach, Sika also follows a verystraight forward philosophy: the right material with the right
TO READ THE FULL VERSION OF

order to overcome the restriction of material characterization
methods, commonly used by the OEM’s acoustic engineers.
These methods do not provide sufficient information about theloss factors of a damping material in either high frequencies orin the case of high loss factors. The OLF results represent thecomposite loss factors in a 3-dimensional, graphic way. Thecolor-coded loss factor is plotted over the frequency band andtemperature range.
Beyond this, Sika’s worldwide acoustic development centers
can also conduct laser vibrometer tests, which enable us todirectly evaluate how damping materials can perform whenapplied on vehicle bodies-in-white.

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3

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