Kleineberg DLR Spring-In ISCM 2008 x
description
Transcript of Kleineberg DLR Spring-In ISCM 2008 x
Institut für Faserverbundleichtbau und Adaptronik
ISCM 2008:„Spring-In“ Simulation
M. Kleineberg, T. Spröwitz
Braunschweig, 07.05.2008
Folie 2 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Content:
- Relevance of the “Spring-In” Effect
- Theory of the „Spring-In“ Effect
- Approach to Identify Material Parameters
- FEM Simulation of Complex Curved Profiles
- Conclusion
Folie 3 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Content:
- Relevance of the “Spring-In” Effect
- Theory of the „Spring-In“ Effect
- Approach to Identify Material Parameters
- FEM Simulation of Complex Curved Profiles
- Conclusion
Folie 4 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Relevance of the “Spring-In” Effect
Sources: AIRBUS, BOEING, NASA
B737-300 B747-400
B787
A300 A310-200
A320 A340-300A340-600
A380
MD80B757 B767 MD90
B777
A400M
A350 XWB
0%
10%
20%
30%
40%
50%
60%
1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Year of First Fight
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are
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om
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site
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ents
A350XWB
B787
Substitution ofHigh Volume„Single Aisle“ Models expected in 2015
Expected Production Scenario
- Typical Production Rate: >350 Aircrafts per Year
- Extreme Competition on World Market and therefore Low Earnings per Aircraft
? Composite Airframe only if Mature Production Technologies available
? ?
Folie 5 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Relevance of the “Spring-In” Effect
Crucial Cost Drivers for High Volume Composite Structures
Part Production ? Typically more than 60% of Costs
Component Assembly ? Typically more than 30% of Costs
Derived Measures to ensure Cost Effectiveness
Minimised Rejection Rate ? Maximum Reproducibility on High Level
Minimised Cycle Times ? Optimized utilisation of Technical Equipment
High Precision Manufacturing ? Shim free Assembly
Folie 6 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Relevance of the “Spring-In” Effect
Problem: “Spring-In” Effect causes severe deformations on curved components
? Direct Rejections due to exceeded Shape Tolerances
? Increased Assembling Effort (Shimming) due to increased Gap Distances
? Component Failure or Damage due to Overloading during Assembling
? Component Failure or Damage due to underestimated Mould-Part-Interaction
? Time-Consuming and Expensive Reengineering of Moulds
Folie 7 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Content:
- Relevance of the “Spring-In” Effect
- Theory of the „Spring-In“ Effect
- Approach to Identify Material Parameters
- FEM Simulation of Complex Curved profiles
- Conclusion
Folie 8 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Theory of the „Spring-In“ Effect
Matrix dominated Out of Plane Properties
Out of Plane Properties: - High Coefficient of Thermal Expansion (CTE)- Noticeable Resin Cure related Effects
In Plane Properties: - Low CTE- Negligible Resin Cure related Effects
Fibre dominated In Plane Properties
Folie 9 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Theory of the „Spring-In“ Effect
( )(1 ) 1
t r t rtot thermal chemical
r r
TT
? ? ? ?? ? ? ?
? ?
? ?? ? ? ?? ?? ?? ? ? ? ? ? ? ?? ?? ? ? ?? ?? ?? ?? ? ? ?? ?
? ? tot????????Total „Spring-In“ Angle ? r: Radial CTE ? t: Tangential CTE ? ? thermal????CTE dependent „Spring-In“ Angle ? r : Radial Laminate Shrinkage ? t : Tangential Laminate Shrinkage ? ?chemical??Cure Shrinkage dependent „Spring-In“ Angle ? T: Effective Temperature Difference
Parameter Definition for a Curved Laminate Section
Calculation Basis
R: Nominal
t: Nominal Laminate Thickness
: Nominal Laminat Angle?
A : Nominal Arc Length, outer/inner o/i
RadiusR’:Radius Measured
t’: Laminate Thickness M
’: Laminate Angle ?
A ’: Arc Length outer/inneroi
easured
Measured
Measured,
RA ’o A’i
Ai
Ao
?
?’
t
R’
t’
Folie 10 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Theory of the „Spring-In“ Effect
Primary “Spring-In” Effects
- CTE in Radial Direction [? r] ? Fibre Volume Content (FVC)- Laminate Shrinkage in Radial Direction [?r] ? FVC- Effective Temperature Difference [? T] ? Process Parameter
Primary “Spring-In” Effects can be Simulated if Coefficients are Available
Secondary “Spring-In” Effects
- Laminate thickness ? Gradient in Degree of Cure- Mould-Part-Mismatch: CTE ? Preload on Boundary Layers- Laminate Imperfections (Voids, Ondulations etc.) ? FVC, Local Stress Induction- Mould-Part-Mismatch: “Spring-In” ? Local Bending Moments- Moisture Expansion of Matrix ? Partial Shrink Compensation- Laminate Radius ? Additional Shear Loads?
Secondary “Spring-In” Effects are difficult to Quantify!
Folie 11 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Theory of the „Spring-In“ Effect
VitrificationGelation
Gelled Glass Region
Sol/Gel Region
Char RegionElastomer Region
Devitrification
Ungelled Glass Region
Liquid Region
Log Time
Tg gel
Tg 0
Tem
pera
ture
Tg Minimum Cycle Time
Minimum„Spring-In“
Time Temperature Transformation (TTT) Diagram for Epoxy Resins
Folie 12 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Theory of the „Spring-In“ Effect
“Spring-In” Effect of L-Shaped Profile
? Independent of Laminate Thickness? Independent of Radius
“Spring-In” Effect of T-Shaped Profiles
? Dependent of Web Thickness? Dependent of Radius
t
Glass epoxy Laminate, L-shaped structure
t
Glass epoxy Laminate, T-shaped structure
Dong, C.; Zhang, C.; Liang, Z.; Wang, B.:
t
Folie 13 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Content:
- Relevance of the “Spring-In” Effect
- Theory of the „Spring-In“ Effect
- Approach to Identify Material Parameters
- FEM Simulation of Complex Curved Profiles
- Conclusion
Folie 14 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Approach to Identify Material Parameters
Approach to Simulate Primary “Spring-In” Effects
Standard Parameters for HT fibres and RTM6 Epoxy Resin? Literature, Data Sheets
? r ´(Radial CTE) and ?r (Radial Laminate Shrinkage) ? Experimental Investigation
? T (Difference between Gel-Point and max. Cure Temperature)? Experimental Investigation
Approach to Simulate Secondary “Spring-In” Effects
Avoidance of Secondary “Spring-In” Effects as far as Possible
Folie 15 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Approach to Identify Material Parameters
Strategy to predict “Spring-In” Deformation
Iteration 2D/3DHybridmodel
„Spring-In“ Deformationof Complex Structures
Step 1: Analyses of 90° Coupons under different Process Conditions? Experimental determination of resulting “Spring-In” Angles
Step 2: Adaption of FEM Simulation to measured Results of 90° Coupons? Combined Coefficient for Chemical Shrinkage and Thermal Expansion
Step 3: Simulation of complex Structures by using the identified Combined Coefficient ? Prediction of Assembling Problems and Stress Concentrations
Step 1 Step 2 Step 3
Folie 16 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Approach to Identify Material Parameters
Step 1: Analyses of 90° Coupons under different Process Conditions
0
20
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100
120
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180
200
0 100 200 300 400 500 600 700 800 900
T V1, Normal
T V2, Tgel 180°
T V3, Tgel 130°
T V7, Tgel 110°
- Variation of ? T by varying the Gel-Point (110°C, 130°C, 180°C)
- Variation of FVC by varyingthe Mould Gap distance
Ni36 RTM Mould with compatible CTE to reduce Mould-Part-Interaction
Automated Process in a heated Press to increase Reproducibility
High Precision Measuring Equipment to quantify Laminate Thickness and Coupon Angle
Folie 17 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Approach to Identify Material Parameters
Step 2: Adaption of FEM Simulation to measured Results of 90° Coupons
2D / 3D Hybrid FEM Simulation
Each Ply of the Laminate issimulated by 3 Finite Element Layers [Type: HEX8]
2D
3D
Folie 18 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Approach to Identify Material Parameters
Step 2: Adaption of FEM Simulation to measured Results of 90° Coupons
Folie 19 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Content:
- Relevance of the “Spring-In” Effect
- Theory of the „Spring-In“ Effect
- Approach to Identify Material Parameters
- FEM Simulation of Complex Curved Profiles
- Conclusion
Folie 20 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
FEM Simulation of Complex Curved Profiles
Step 3: Simulation of Complex Structures
2D / 3D Hybrid Models
Integral Z-Profiles
Integral Z-Profiles
Integral LCF-Profiles
UDReinforcedInner andMiddleChord
Profiles that have been investigated
Folie 21 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
FEM Simulation of Complex Curved Profiles
Isostatic Boundary Conditionat Free Edge? Global „Spring-In“ Angle? Stress Analyses
Assembly Boundary Condition
? Stress Analyses
Step 3: Simulation of Complex Structures: Boundary Conditions
Folie 22 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
FEM Simulation of Complex Curved Profiles
Step 3: Simulation of Complex Structures: Simulation Results
Integral Z-Profiles
Integral LCF-Profiles
Global “Spring-In” Effect:? Global Radius Decreases
Global “Spring-In” Effect: ? Global Radius Decreases
Integral Z-Profiles
Global “Spring-In” Effect:? Global Radius IncreasesUD
UD
UD
Stress Level 1:No significant Increase of Stress Level under Assembly BoundaryConditions
Stress Level 2:Stress Level and “Spring-In” Effect can be reduced by 50% by applying low Gel-Temperatures
Folie 23 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Content:
- Relevance of the “Spring-In” Effect
- Theory of the „Spring-In“ Effect
- Approach to Identify Material Parameters
- FEM Simulation of Complex Curved Profiles
- Conclusion
Folie 24 > Vortrag > AutorDokumentname > 23.11.2004Institut für Faserverbundleichtbau und Adaptronik
Conclusion
„Spring-In“ Deformation is Highly Dependent on Gel-Temperature and Fibre Volume Content
? Reproducible Process Conditions Required for Cost Effective, High Precision Manufacturing
Simple L-Shaped Coupons can be used to investigate the “Spring-In” Behaviour ofComplex Composite Structures
? Realisation of Spring-In Compensated Manufacturing Moulds possible
Lower Gel-Temperatures lead to reduced “Spring-In” Angles but also increaseCycle Times significantly
? Reduced “Spring-In” Angles indicate a lower Stress Level in the Laminate