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LASD Coatings Optimized for Damping of Aluminum Intensive Vehicle Bodies
Global Automotive Lightweight MaterialsAugust 18-20, 2015
Ion Pelinescu, Ph.D.NVH-Acoustics Engineering Associate
Coatings Innovation CenterAllison Park, PA
Content
LASD Acoustical Coatings Technology
High Aluminum Body Content - Implications
Aluminum vs. Steel Substrates
Damping Coatings - NVH performance Designed for Aluminum
Structures & Modal Densities – NVH
Noise & Damping – Correlations
Concluding Remarks
LASD Acoustical Coatings Technology
Liquid Applied Sound Damper
Vehicle sound package component Mitigates structure-borne NVH issues
Fully automated application process
Fully integrated with the paint shop cure processes
®
High Aluminum Vehicle Body Content - Implications
Noise-vibration-harshness (NVH): Sources → Paths → Receivers Aluminum intensive vehicle bodies can be more than 3 dB noisier than steel
bodies, with the same sound package (e.g. SAE papers 2015-01-2343, 2015-01-2302)
Reduced weight leads to increased NVH issues at higher frequencies
Preserved stiffness/strength at lower modulus leads to increased gage
Sound package - mitigate NVH issues efficiently without adding weight
Center Point Modal Testing – 1D beam(ISO 16940:2008) Symbol Units ST AL
Modulus 𝐸 GPa 200 62
Thickness 𝑡 mm 0.8 1.2
Bending Stiffness
𝐸 𝑡12 (1 − 𝜗 )
N•m 9.4 9.8
0 400 800 1.2k 1.6k 2k 2.4k 2.8k 3.2k[Hz]
-70
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60[dB/1u (m/s^2)/N]
FRF STeel 0-8mm RT blank (Magnitude) \ FFTFRF ALum 1-2mm RT blank (Magnitude) \ FFT
Stiffness Mass
0 400 800 1.2k 1.6k 2k 2.4k 2.8k 3.2k[Hz]
-50
-40
-30
-20
[dB/1u (m/s^2)/N]
FRF STeel 0-8mm 40C LASD2 (Magnitude) \ FFTFRF ALum 1-2mm 40C LASD2 (Magnitude) \ FFT
StiffnessSTAL
Stiffness of Aluminum & steel substrates are statically matched Aluminum emphasizes stiffness vs. mass dynamic participations
Aluminum vs. Steel - SubstratesM
agni
tude
FRFPlots
Coated BeamsBlank BeamsFrequency (Hz)
(f coa
ted/f
subs
trate
)2
1st mode 2nd mode 3rd mode
(Res
. fre
quen
cies
ratio
)2~
(Stif
fnes
s R
atio
)
AL @1.2mmST @0.8mm
Center Point Modal Testing Results
Frequency (Hz) – (log scale)
Stiffness ratios of AL & ST coated substrates are highly differentiated at frequencies > 300Hz
Noise & vibration transmission through Aluminum structures expected to shift at higher frequencies
Aluminum vs. Steel - Stiffness
Temperature (oC)
Dam
ping
Los
s Fa
ctor
@25
0Hz
Damping Performance Designed for Aluminum
Coating A Coating B
Center Point Modal Testing – 1D beams
AL @1.2mmST @0.8mm
Most damping treatments designed for steel do not perform at optimum level on Aluminum at similar weight/area
Coating optimized for Aluminum - increased damping performance
Most damping treatments designed for steel show lower damping performance at higher modal frequencies
Coating optimized for Aluminum: increased damping above 300Hz
Coating C
Coating D
Dam
ping
Los
s Fa
ctor
Temperature (oC)
Center Point Modal Testing – 1D beams
1st mode 50 - 120Hz2nd mode 270 - 650Hz3rd mode 700 - 1700Hz
Damping Performance Designed for Aluminum
Complex Structures & Modal Densities
Panels exhibit higher modal densities vs. beams …
BIW is a complex multi-panels & multi-beams assembled structure, and ….
Resonance frequencies of Aluminum structures are shifted higher, while …
Coincidence frequencies for Aluminum panels < 8-9 kHz
1 kHz band
PanelBeam
Without damping coating
With damping coating
FRFPlots
Frequency (Hz)Band Range250 176-353500 353-7071000 707-14142000 1414-2828
LASD coated panels show high damping above 500Hz vs. CLD steel
LASD performs optimally in higher modal densities structures (i.e. BIW) and at frequencies >500Hz
Damping Performance
Dam
ping
Los
s fa
ctor
Test samples: Size 0.8m X 0.8mCoated area: 0.6m X 0.6m
Modal Testing - 2D Panels(PPG SAE paper 2011-01-1632)
Damping & Noise - Correlations
Panels with higher damping consistently produce lower noise
Panel APAMAT SPL (dB) Panel Damping Loss Factor
Panel groupA B C D E F A B C D E F
500 (Hz)
1000 (Hz)
2000 (Hz)
1/1
octa
ve b
ands
Concluding Remarks
Aluminum BIW changes NVH transmission path significantly Aluminum substrates shift structural resonances at higher frequencies
vs. steel substrates at similar stiffness
Damping treatment products designed for steel substrates do not perform optimally on Aluminum
LASD optimized for Aluminum: Higher damping performance on Aluminum compared to steel Higher damping at higher frequencies (>300 Hz) Good damping performance in high modal densities structures (e.g.
panels, BIW)
Author Contact InfoIon Pelinescu, Ph.D.NVH-Acoustics Engineering Associate
PPG Industries, Inc.Coatings Innovation CenterAllison Park, PA 15090Phone: 412-492-5402Email: [email protected]
Q & A