This presentation demonstrates how to use Optistruct to predict the vibration levels of a floor pan and how to model Liquid Applied Sound Deadeners to reduce the vibrations with a minimum weight addition. Speakers Jean-Paul Allal, R&D Project Leader, PPG Automotive Adhesives and Sealants

1. Modeling of weight and vibration reduction
using high performance LASD
in the automotive industry
Jean-Paul ALLAL R&D Engineering Project Leader
September 2015

2. Aug-15
PPG Automotive Adhesives & Sealants
• Key facts :
 > 600 employees
 Worldwide presence
 Complete paint-shop &
body-shop portfolio
 Fundamental research with resin
synthesis capability
2
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
1982 1984 1992 2000 2002 2004 2008 2011 2015
1982
PPG acquired
Hughes Products
(NA-Adrian)
1983
1984
PPG acquired Industrie
Vernici Italiane (IVI)
from FIAT Group
1983
PPG acquired
Cipisa which was
then renamed to
PPI Iberica
2002
PPG acquired
Grow Chemical
2008
PPG acquired Dow
sealants in NA
April 2015
PPG acquired
Revocoat
1992
PPG started a JV
with a Korean A&S
start-up and initiated
A&S activities
Ferndale, Adrian,
Michigan
R&D Synthesis :
Pittsburgh, Pa
Pinhais, Brazil
Wuhan, China
Pondicherry, India
Kolomna, Russia
Bursa, Turkey
St Just, France :
HQ & Center of
Excellence
Camarma,
Valladolid,
Spain
Ahmedabad ,India
Quattordio
Italy
Partnership with Asahi Rubber, Japan &
Bokwang Corporation, Korea
Busan, Korea

3. Aug-15
PPG Adhesives & Sealants : Portfolio
3
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
Body-shop : Adhesives
Body-shop : Antiflutters LASD and BPR UBC & Paint shop sealers
Body-shop : Parts

4. Aug-15
Technical trends at OEM’s
4
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
 Reduction of curing conditions
 Compact paint-shop,
multifunctional materials
 Platform strategy
• Bonding vs. welding
• Lighter materials
• Substrate :
 Thin layer as HSS
 Alu, Mg
 Composites
 Reduction fogging & emissions
Mass reduction at targeted
performances
Cost optimization
Clean & greenAcoustical comfort
 Engines
 NVH treatment

5. Aug-15
WEIGHT SAVINGS in AUTOMOTIVE
• Strategies : Redesign, downsizing, lighter or more efficient materials
5
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
Weight saving to consumption
real cars data :
100 Kg  0.5 L/100 km

6. Aug-15
PPG ENGINEERING SUPPORT
6
Engineering support
Testing
Material
testing
Oberst
Drop Tower
Tensile/compre
ssion
DMA
…
Static
Oil canning
Deformation
Noise
Door slam test
Static / driving
car noise
Vibration
Scanning head
Laser
accelerometers
Modeling
Static
linear
non linear
Thermal
deformation
Modeling of
read through
Stress
calculations
Modal
response
Frequency
response
Random
excitation
Measured
excitation
Dynamic
Linear
Non linear
(CRASH)
0
0,02
0,04
0,06
0,08
0,1
0,12
0,14
0,16
30 50 70 90 110 130 150 170 190 210 230 250
Mobility(mm/s/N)
Frequency (Hz)
0,E+00
1,E-02
2,E-02
3,E-02
4,E-02
5,E-02
6,E-02
7,E-02
AVT DRT
CTR DRT
TUNNEL
AVT GAU
CTR GAU
PIED ARRASSISE
TRAIN
ARR
COFFRE
GAMELL
E
MOYENN
E
RESP_DAMPER
70-250Hz
RESP_NUE 70-
250Hz
The engineering main target is to provide expertise to show the best usage of
our materials.
We have 2 methodologies : Testing and Modeling
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
PPG Modeling : NVH but also Crash, Thermal, …
using Optistruct &/or Radioss

7. Aug-15
Damping products will convert to heat a part of the strain energy of the panels
and reduce the mobility (or the vibration levels) and the acoustical emission.
Vibrations
• Sources
• Amplitudes
Structure
• decoupling
• Transfer path
Panels
• Loud speakers
• Modal shapes
Noise
• Acoustical level
• Perceived quality
What are we speaking about ?
7
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
A car body is made of a rigid frame and of panels.

8. Aug-15
Energy
absorption
Very high
damping (η)
or tg(δ)
different
θ°C
Young’s
modulus /
stiffness
Substrate &
material
Thickness
Material
deformation
strain
What are damping coatings ?
8
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
Common industrial products :
- Parts (mastic pads or constrain layers) most of the time manually fitted
- Pumpable products applied with robots

9. Aug-15
Characterization & Oberst method
The main characteristic of dampers is measured with DMA that provide values of η (or of
tg(δ)) & of product Young’s modulus with no sensitivity to adhesion phenomenon’s or
more frequently in the automotive industry with Oberst method (DIN 53440 – ISO 6721-3 – D45 1809 - … )
9
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
Vibration
response of a
steel bar
•Thickness 1mm
•Coated with product
-3dB (δF/F)
method
•Modes 2, 3, …
•about 100Hz, 300Hz,
…
Linear
Interpolation
•Oberst result
@200Hz (for most
OEMs)
Results in %
•For a given surface
weight & for each θ
°C
Frequency (Hz)

10. Aug-15
Characterization & Oberst method
• The Oberst value is dependant of the material and of the substrate (material &
thickness) and is an interpolated value @200Hz.
• The damping material is frequency dependant (this is masked in a single Oberst value)
and in the calculations it should be used as such. As a consequence there is a
calculation time penalty (It increases a lot and for a full car optimization it comes
difficult).
• For aluminum substrates results are quite different than for steel (because of higher
frequencies). It is also common sense that on such substrates the natural frequencies of
the panels are more important so analysis have to be made more carefully on higher
frequency range.
10
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

11. Aug-15
Modeling techniques are the same for all the chemical basis except for the
constraint layers because of the 3rd layer : the aluminum foil. (1st is the panel
material and 2nd is the damping coating).
Technology Mastic Pads
Constrain
Butyl/alu
EPOXY RUBBER PVC Acrylic EPOXY Rubber
Density (wet/dry)
1,4 à 2 magnetic or
adhesive
1,6 (the paste) 1,6 1,6
1,3
1,3
1,5
,9
1,6 1,6
Surface weight for 14%
damping @200Hz
4 kg/m² 1,8kg/m² 3 kg/m² 3 kg/m² 4 kg/m²
1,8 kg/m² dry
2,3 kg/m² wet
3 kg/m² 3 kg/m²
Maxi oberst damping /
surface weight
30% - 10kg/m² >30 - 4kg/m² 19% - 4kg/m² 19% - 4kg/m² 16% - 6,5kg/m²
>30%: 4kg/m² sec
ou 5,1kg/m² cru
25% - 6,5kg/m² 25% - 6,5kg/m²
VOC / Fogging / Toxproof Low No No No Yes No No Low
Sealing capability No ??? Yes Yes Yes No Yes Yes
Underbody protection No No No No
Yes
(ep>1mm)
No
Yes
(ep>2mm)
No
Print through risk 2/5 1/5 3/5 3/5 2/5 1/5 3/5 3/5
Paint ShopBody ShopAll Shops
Damping products may have different chemical basis.
Technology comparison
11
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

12. Aug-15
Example of real application in an automotive plant.
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PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
VIDEO 

13. Aug-15
Example of automotive floor optimization
13
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
• This study is made on a -non real- floor pan to avoid confidentiality issues.
• AS an example, this presentation will focus on the floor pan only. It is always more
efficient to do this study including the floor pan, the firewall, the doors, the roof, …
• Frequency range of optimization depends on mesh quality & size. In this example it’s
up to 250Hz.
• Damping coatings absorb the strain energy of the panels, thus the first modes
(flexion/torsion) of the car body are not interesting. We will focus on panel vibrations
reduction.
• We decided to explain step by step the methodology knowing that in HYPERMESH the
NVH Process manager does all the pre-processing automatically.
• We don’t use automatic optimization since it doesn’t allow to understand the physics.

14. Aug-15
0
50
100
150
200
250
300
350
400
450
500
0 100 200 300 400 500 600 700 800 900
Modefrequency(Hz)
Mode #
Numberof modes / frequency
The first stage of a damping optimization (after validation of the mesh quality) is to
perform a modal analysis of the car body.
- Define the EIGRL card (in this example up to 250 Hz)
- Define the LOAD STEP : Normal modes
- Define the GLOBAL OUTPUT REQUEST : VELOCITY and ESE (Element Strain Energy)
Because of the small number of nodes of this mesh, the standard LANCZOS method
doesn’t create any calculation size or speed issue for OPTISTRUCT.
If the mesh is huge, the AMSES card (Automatic Multi-Level Sub-Structuring Eigensolver
Solution) may be activated and the EIGRL card changed to EIGRA.
The results are vey close and calculation size & speed is much smaller.
Number of nodes: 181 887
Number of elements: 184 150
Number of rigid elements: 3 350
Number of rigid element constraints: 23 850
Number of degrees of freedom: 1 084 674
Number of non-0 stiffness terms: 27 242 403
Number of ELAS1 elements: 19 902
Number of HEXA elements: 453
Number of QUAD4 elements: 155 744
Number of TRIA3 elements: 8 051
MODAL ANALYSIS
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PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

15. Aug-15
1. Boundary conditions
In the frequency response calculation (modal response) the
excitation points have to be carefully chosen. They have to be as
close as possible to real excitation forces but also have to be on
parts rigid enough to transfer the excitation to all the body with
small resonance effects.
2. Loads and control cards
a) A set (1) is defined with the nodes to be monitored
A Punch and a H3D files are generated with the speeds of the
nodes defined in the set.
b) This run (Freq. Resp. Modal) has these cards:
i. EIGRL (1): Modal analysis up to 500Hz (has to be at
least 2x the higher frequency response).
ii. FREQ1 (2): calculation of responses from 5 to 250Hz
with steps of 0.5Hz (490 steps)
iii. Loading RLOAD2 (5) is made with a Force (4) of 1N on
a node (5027) and is « multiplied » by the curve Tabled1
(3). This permits –if needed- to have frequency
dependant excitations.
c) A Damping value of 1% is given to all the steel material cards.
This value comes to 2% for aluminum.
It represents the material + the structural damping.
OUTPUT,PUNCH,FL
OUTPUT,H3D,FL
VELOCITY = 1
SET 1 = 19975, …
SUBCASE 1
LABEL REPONSE FREQ
ANALYSIS MFREQ
MPC = 1
METHOD(STRUCTURE) = 1
FREQUENCY = 2
DLOAD = 5
FREQ1 2 5.0 0.5 490
RLOAD2 5 4 3 0
EIGRL 1 500.0
MASS
TABLED1 3 LINEAR LINEAR
+ 0.0 1.0 1000.0 1.0ENDT
FORCE 4 5027 01.0 0.0 0.0
1.000
TABLED1FORCE
FREQUENCY RESPONSE : Models Pre-processing
15
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

16. Aug-15
3. Definition of the control points
a) The control points (nodes) are uniformly selected on every panel to be dampened.
b) We must have a points density high enough to get an average mobility of each panel.
c) In this example we selected 99 points grouped in 10 zones.
d) The Post-treatment may be done in Hypergraph to get the average amplitude for each
area of the floor pan and in total
e) We may also use the ERP (Equivalent Radiated Power) that provide
for each selected panel similar results ( is the area associated to each node and the normal speed of
the node) and it may be minimized using an automatic optimization.*
f) The ERP in very useful when for post-process we use the NVH Process utility to look
at the modal participation of each panel or grid.
g) The PEAKOUT parameter has not been used in this “small” model but is very useful
when model is huge and there are a lot of modes and storage space is limited.
FREQUENCY RESPONSE : Models Pre-processing
16
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

17. Aug-15
FRT RIGHT
FRT LEFT
TUNNEL
CTR
RGHT
CTR
LEFT
MIDDLE
SEAT
AREA
REARMEMBER
BOOT
SPARE
WHEEL
Exampleofpostprocessingperpanel
FREQUENCY RESPONSE : panel post processing
17
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
0,0001
0,001
0,01
0,1
1
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
Averagemobility(mm/S/N)
Frequency (Hz)
FLOOR PAN ANALYSIS - AVERAGE PANEL MOBILITY
FRTRIGHT CTR RIGHT

18. Aug-15
0,001
0,01
0,1
1
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
Averagemobility(mm/s/N)
Frequency (Hz)
FLOOR PAN - AVERAGEMOBILITY
Globalpost-processing/strainenergylocations
FREQUENCY RESPONSE : Global Post processing
18
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

19. Aug-15
0,001
0,01
0,1
1
10
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
Averagemobility(mm/s/N)
Frequency (Hz)
FLOOR PAN - AVERAGE MOBILITY FOR EACH AREA
AVERAGE FRT RIGHT CTR RIGHT TUNNEL FRT LEFT CTR LEFT MIDDLE SEAT AREA REAR MEMBER BOOT SPARE WHEEL
Globalpost-processing/strainenergylocations
FREQUENCY RESPONSE : Global Post processing
19
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

20. Aug-15
Globalpost-processing/strainenergylocations
FREQUENCY RESPONSE : Global Post processing
20
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

21. Aug-15
For the models in OPTISTRUCT, the material card for the composite steel/Damper is PCOMP where we will
fill the field GE that represents the damping of this component. This has not to be done in the material card.
As already mentioned, the materials are frequency dependant so we may also use the MATF1 card and
tables (TABLED1) for Young’s modulus and Damping if needed.
For this study, we will use as example an acrylic material and only one damper thickness.
Here is a HYPERMESH screen copy with the useful parameters:
Damper
measured
Oberst
Damper
on 0,62mm
steel
Damper
on 0,67
steel
Steel thickness mm 1,00 0,62 0,
Damper thickness mm 3,12 3,12 3,
Steel Young's modulus MPa 208000 208000 2080
Damper Young's modulus MPa 250 250 2
Damper density 0,80 0,80 0,
Dampermaterial Damping η 0,91 0,91 0,
Damper surface weight kg/m² 2,50 2,50 2,
Composite Loss Factor GE 20,70% 74,02% 74,0
FREQUENCY RESPONSE : MATERIAL CARDS
21
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
32
32,5
33
33,5
34
34,5
35
35,5
36
110 115 120 125 130 135 140 145 150 155
VALIDATION CARTE MATERIAU - OBERST RESPONSE SP400
X= 113 Hz
Y=32,24 dB X= 152,8 Hz
Y=32,24 dB
Model results :
Freq: 121,8 Hz
Damp : 30,2%
Test results :
Freq: 126,7 Hz
Damp : 30,5%
difference :
Freq: 4,9 Hz --> 3,9%
Damp : 0,3% --> 0,1%
X= 131,8 Hz
Y=35,24 dB
Mode 1 Damping measurement

22. Aug-15
The definition of the damping product mapping is made with these considerations :
Vibration levels / mobilities of each panel and information from strain
energy pictures
The damper material is always more efficient on thin panels, so we avoid to
put on welded panels junctions with double thickness (this is easily
achieved with robotic application).
Keep an homogeneous treatment and instead of too high thickness it’s
sometimes better to increase the treatment surface.
Check the result and optimize the mapping till the target (performance &
product mass) is not reached.
PRODUCT MAPPING
22
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

23. Aug-15
The patterns are defined as per former slides and result mapping is:
Covered surface = 0.69m² - product mass = 1.722 kg
PRODUCT MAPPING
23
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

24. Aug-15
0,E+00
1,E-02
2,E-02
3,E-02
4,E-02
5,E-02
6,E-02
7,E-02
FRT
RIGHT
CTR
RIGHT
TUNNEL
FRT LEFT
CTR LEFT
MIDDLE
SEAT
AREA
REAR
MEMBER
BOOT
SPARE
WHEEL
AVERAG
E
0,E+00
1,E-02
2,E-02
3,E-02
4,E-02
5,E-02
6,E-02
7,E-02
FRT
RIGHT
CTR
RIGHT
TUNNEL
FRT LEFT
CTR LEFT
MIDDLE
SEAT
AREA
REAR
MEMBER
BOOT
SPARE
WHEEL
AVERAG
E
RESP_DAMPER
70-250Hz
RESP_BARE 70-
250Hz
5dB
OPTIMIZED LAYOUT RESULTS
24
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD
-50
-45
-40
-35
-30
-25
-20
-15
-10
70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
Averagemobility(mm/s/N)
Frequency (Hz)
FLOOR PAN - AVERAGE MOBILITY
NAKED FLOOR DAMPENED FLOOR
5dB
0,E+00
1,E-02
2,E-02
3,E-02
4,E-02
5,E-02
6,E-02
7,E-02
FRT RIGHT CTR RIGHT TUNNEL FRT LEFT CTR LEFT MIDDLE SEAT AREAREAR MEMBER BOOT SPAREWHEEL AVERAGE
Averageresponse(mm/s/N)
Panel average response 70-250Hz
RESP_BARE 70-250Hz
RESP_DAMPER 70-250Hz

25. Aug-15
Mastic Pads PVC Acrylic Epoxy Rubber
Mass (kg) 3,822 3,727 1,720 2,867 2,962
Reduction (%) 0,0% 2,5% 55,0% 25,0% 22,5%
0,0%
10,0%
20,0%
30,0%
40,0%
50,0%
60,0%
0,000
0,500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
Massreduction(%).BasisisMasticPads
Productmass(kg)
Product mass for 40% vibration decrease
The floor pan vibration level is reduced from 4.4 mm/s/N to 2.7 mm/s/N so a reduction of
40% with 1.72kg of damping product.
We conducted same study with other generic products and for the same vibration level got :
FUNCTIONAL SUMMARY
25
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

26. Aug-15
All the meshes were generated in HyperMesh, the runs were submitted with OPTISTRUCT
and for Post processing we used : HyperMesh (POST), HyperView, HyperGraph and
Microsoft Excel.
This is only a BIW model, same methodology may be used for trimmed car or other models.
For a trimmed car, number of DOF is huge so required memory and calculation time are
also huge. The use of the AMSES method permits a time reduction up to 90%. For such a
mesh, the number of modes comes to be incredibly high so the relevant strain energy maps
are hard to select and to visualize and the PEAKOUT option is very useful. Also the NVH
utility in Post process help to visualize the panels or grids modal participation.
I would recommend in this case to perform the study in two steps, first doing the
optimization using a simplified mesh (only the BIW) and second as a validation using the
optimized patterns from the first on the trimmed body mesh.
As already mentioned, the use of the ERP calculation is useful to get direct results with
smaller result files. It also reduces the post processing time (no need to perform in the post
process an average of all the nodes) and may be used for optimization purpose.
CONCLUSION
26
PPG REVOCOAT – Modeling of automotive weight and
vibration reduction using high performance LASD

27. THANK YOU FOR YOUR ATTENTION
QUESTIONS ?
Jean-Paul ALLAL
Email: allal@ppg.com