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: pelinescu@ppg.com

Q & A