Size Optimization process of an Exhaust System Mauricio Monteagudo G. R&D Exhaust Durability Manager Faurecia R&D Center, France.

2nd European Hyperworks Technology Conference 2008 Strasbourg, France.

Content


Introducing Faurecia




Aim




Virtual Durability Product Development Brief review= Low Frequency Analysis ?!
Problem description





Size Optimization




Summary & Conclusions

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Introducing Faurecia

Faurecia is an expert in 6 major modules Acoustic package n°3 in Europe

Exhaust system n°1 in Europe n°2 worldwide

Seating n°2 in Europe n°3 worldwide

Door panel / Modules n°1 in Europe n°1 worldwide

Instrument panel / Cockpit n°1 in Europe n°1 worldwide

Front end n°1 in Europe n°2 worldwide

4

International ESPG footprint

NORTH AMERICA 6 Production plants 3 JIT 1 D&D center

EUROPE 9 Production plants 10 JIT 1 R&D center 3 D&D centers USA Korea China

Mexico

Plants

Brazil

ASIA 5 Plants 1 Customer office 2 D&D centers Japan

ROW 3 Plants 1 JIT

R&D Center D&D Center

Argentina

South Africa

Customer Office

www.faurecia.com 5

Aim

Aim


Applying Size Optimization (modification of properties) approach to:


NVH Decrease Hanger Forces
Early selection of decoupling elements dynamic characteristics





Durability Bending Moments at the I/O volumes
Stress values vs. worst resonant frequencies
Lightweight if loads are lower thanks to the more efficient decoupling values.



Time

Global virtual durability development to optimize the dynamic behavior of Exhaust Systems.




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Virtual Durability Development

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Overview of Exhaust System

Hot End

Cold End

Emission control

Acoustic

Structural integrity Durability 2nd Hyperworks Technology Conference Strasbourg, France. Property of Faurecia - duplication prohibited

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Virtual Durability Development

Complete Exhaust Validation

Vehicle Level

SOR

System Level Low Frequency [Engine load] ~ 20–250 Hz

Very Low Frequency

■

Component Level ■

[Road & Engine loads] ~ 0-20 Hz

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Engine Bench Electrodynamics Bench ■

Subsystem Level

■

Exhaust System Key Life Test

Uni (Bi)-axial Force Loading Bench 10

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Brief review = Low Frequency Analysis Engine Excitation Load


To evaluate the reacting forces at each hanging point that could

induce Structure Borne Noise in the Vehicle or NVH

40µ Culasse Culasse Culasse Culasse

Amplitude m

30µ

X- Order: 1.5 X- Order: 3.0 X- Order: 1.5 X- Order: 3.0

RMS15-Jul-08 RMS15-Jul-08 RMS22-Jul-08 RMS22-Jul-08

09:07:53 09:07:53 22:08:37 22:08:37


To compute the bending moments, at inlet/outlet of volumes.

20µ


To evaluate the stress map for each measuring points for worst

10µ

resonant Frequencies tuning the structural experimental damping

0 1k

2k

3k

4k Rotation speed - rpm

K

Static& Dynamic

*

5k

6k

 Kx    Ky   Kz     Kθx     Kθy   K θ z  

6.5k

Hanger Force Flex Coupling CS

Bending moment at the I/O of volumes

Isolators K

Static& Dynamic*

 Kx    Ky   Kz  

Worst Resonant Frequencies

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CS

Problem description Today know-how to isolate engine vibrations using standard decoupling elements (Flex coupling & Isolators)




Challenge To know the most accurate linear dynamic stiffness values by optimization loops to evaluate the reacting forces at each hanging point that could induce NVH




RF3 Z direction

RF3 Z direction 16

60

14 50

12 40

10

AVG 30

ARD ARG CDC

Force (N)

Force (N)

AVD

AVD AVG

8

ARD ARG

6

CDC

20

4 10

2 0

0 30

50

70

90

110

Frequency (Hz)

Without Flex 2nd Hyperworks Technology Conference Strasbourg, France. Property of Faurecia - duplication prohibited

130

150

30

50

70

90

110

130

150

Frequency (Hz)

With Flex

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Size Optimization

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Size Optimization Target
To

minimize hanger force in each direction < 10 N


To

keep lower stress map and bending moments < 100 N*m

Potential design parameters


Flex Coupling: Kx, Ky, Kz, Hx, Hy, Hz (6)




Isolators: Kx, Ky, Kz (2x3 = 6) K

K

Static& Dynamic*

 Kx    Ky   Kz  

Static& Dynamic*

 Kx    Ky   Kz     Kθx     Kθy   K z θ  

CS

CS

Inputs

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Engine behavior load (FRF) for critical Eigen values




Temperature map loaded




Damping values are fixed according experimental tuning 14




Decoupling elements dynamic characteristics data base 14

Size Optimization 1st

Rear isolator

Loop

Front isolator

Flex

Lower bound

Initial values

Upper bound

Optimized values

Kx (N/mm)

500

1000

1500

500

Ky (N/mm)

100 000

200 000

300 000

300 000

Kz (N/mm)

100 000

200 000

300 000

100 000

Kθx (Nmm/rad)

75 e+05

15e+06

225e+05

225e+05

Kθy (Nmm/rad)

400 000

800 000

1.2e+06

81 362

K θz (Nmm/rad)

400 000

800 000

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1.2e+06

1.2e+06

Front Isolator

Lower bound

Initial values

Upper bound

Optimized values

Kx (N/mm)

4.8

16

17

17

Ky (N/mm)

4.8

16

17

17

Kz (N/mm)

24

40

41

41

Kx (N/mm)

2.4

8

14

14

Ky (N/mm)

2.4

8

14

14

Kz (N/mm)

12

20

28

12

Rear Isolator

15

15

Size Optimization

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Size Optimization 2nd

Rear isolator

Loop

Front isolator

Flex

Lower bound

Initial values

Upper bound

Optimized values

Front Isolator

Lower bound

Initial values

Upper bound

Optimized values

Kx (N/mm)

100

1000

2000

351

Kx (N/mm)

1.6

16

32

32

Ky (N/mm)

20 000

200 000

400 000

400 000

Ky (N/mm)

1.6

16

32

5.5

Kz (N/mm)

20 000

200 000

400 000

30 585

Kz (N/mm)

4

40

80

10

Kθx (Nmm/rad)

1.5e+06

15e+06

30e+06

30e+06

Kθy (Nmm/rad)

80 000

800 000

1.6e+06

749 512

Kx (N/mm)

0.8

8

16

14

K θz (Nmm/rad)

80 000

800 000

1.6e+06

1.6e+06

Ky (N/mm)

0.8

8

16

9

Kz (N/mm)

2

20

40

2

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Rear Isolator

17

17

Size Optimization

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Size Optimization Max Von Misses stress

With initial values Frequency (Hz)

34

43

61

69.5

109

Von Mises stress (MPa)

4.8

6.9

5.6

5.3

10.7

116. 5 1.5

141.5

116. 5 7.3

134

5.9

With optimized values (1st loop) Frequency (Hz)

35

43

61

68.5

110

Von Mises stress (MPa)

2.8

18.2

3.7

7.1

14.5

2.9

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Size Optimization Typical dynamic characteristics values (example) 140

+ Z Direction

120

N/mm

100 80 60 40 20 0 0

50

100

150

200

250

300

350

400

Hz

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Summary & Conclusions

Summary & Conclusions Size Optimization approach was developed for Exhaust Systems in Low frequency domain.


An case study was presented here and proved the Size Optimization approach can predict Flex coupling and Isolators dynamic characteristics in the earliest virtual development stage.


The compromise of decreasing hanger forces and keeping lower stress values and bending moments is possible.


The predicted results were correlated reasonably with observed results from Faurecia decoupling elements data base assuring the steadiness of results.




Size Optimization is able to predict dynamic performance of exhaust which 22 enables to avoid the treat of presumptive dynamic stiffness values in order to reach the design targets applying advance mathematical tools like OptiStruct.


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Thank you for your attention. References Mauricio Monteagudo Galindo, Science and Technology Designing Exhaust Systems. SAE 2003 Noise & Vibration Conference, 2003-01-1656.




M. Monteagudo, J. Clavier, T. Lauwagie, J. Strobbe, E. Dascotte, Optimization of the Dynamic Response of a Complete Exhaust System, ISMA2008





OptiStruct, User’s Manual, version 8.

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Contact Mauricio Monteagudo Galindo R&D Exhaust Durability Manager Faurecia R&D / France. Tel: +(33) 3 81 99 25 63

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[email protected]

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