Structures Technology for Future Aerospace Systems 2000 Computers Structures
Load Introduction into Aerospace Structures€¦ · Load Introduction into Aerospace Structures ......
Transcript of Load Introduction into Aerospace Structures€¦ · Load Introduction into Aerospace Structures ......
Load Introduction into Aerospace Structures Dr. Tamas Havar,
Airbus Group Innovations
Symposium 5th anniversary of Institute of Carbon Composites
POC: [email protected]
Introduction
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Investigated Composite Load Introduction Structures in Aircraft
CFRP Rear Link
A340 CFRP Spoiler
Composite
4-Bar Linkage
Flap Support
CRFP Flap Load Introduction Rib
Innovative Flap Load Introductions
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Flap
LIR
Aircraft Structures:
• Continuous development of aircraft structures
• Increased use of composite materials
• Composites currently used in frame structures
• Metallic Load Introductions
High Lift System – Composite Flap:
• Composite skin with stringers
• Composite ribs and Spars
• Except metallic load introduction rib
Aim: Innovative composite design for Load Introduction Rib (LIR)
A330 / A340
Innovative Flap Load Introductions
Aim of Project:
• Redesign of metallic LIR => innovative composite LIR
• Requirements:
• Equal design space, attachments,…
• Load transmission from flap track into flap
• Resistance against temperature, humidity, chemicals,…
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Composite Flap
Metal - LIR
Flap Structure
Project Goals:
• Innovative composite design (No black metal!)
• Low manufacturing costs
• Low weight
• High robustness => low maintenance costs
Composite LIR
Project Team:
• Airbus Group Innovations
• Airbus (Lead)
• Airbus Helicopter
• Airbus Defense and Space & Premium AEROTEC
• IVW Kaiserslautern
Innovative Flap Load Introductions
New Composite Textile Preform Design
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DS Rib
DS Bracket
LIR FS Attachment
SL Attachment
RL Attachment
RS Attachment
Innovative Flap Load Introductions
Design Process
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Modification of
exist. Flap FEM
New Design of
LIR (CAD)
New FEM
Model of LIR Integration of
LIR Model in
Flap Model
Integration of
Rivets
Part C
Part B
Part A
Application of
Loads
Analysis of
Stresses
Innovative Flap Load Introductions
3D Sizing with effects of defects
• Plies milled (Waviness => too thick)
• Fiber orientation taken from pre-form
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Results of Analysis
• Successful Sizing of LIR
• Few critical points
• Local small Reserve Factors (RF) dependent on load case
•Fiber compression S11min
•Matrix tension S22max
• No critical delaminations calculated S12, S13 und S23
• No matrix crack at gusset fillers
1
2 2
1 2
3
Innovative Flap Load Introductions
Manufacturing (Airbus Helicopters)
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Preforming of Parts
• Automated NCF Cut Out
• Positioning of Load Introduction
• Draping of Rib Layers
• Precompatcting
• Adding of Reinforcement Layers
• 3D Stitching of Edges
• 3D Cutting of Edges
• Automated Pre-form QS
Innovative Flap Load Introductions
Manufacturing (Premium Aerotec)
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Infiltrated Parts
• LIR with CFRP Lugs
• 3D Reinforcement
• Drive Ribs
• Drive Bracket
• Pi Profiles
• FS-Attachments
• Aux Spar
Innovative Flap Load Introductions
Manufacturing (Airbus)
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Assembly
• Shortening of A340 OB Flap
• Reinforcement of Lower Skin
• Assembly of LIR
• Assy. DS Rib and Bracket
• Assy. Clamping Ribs
Top View Bottom View
Innovative Flap Load Introductions
Validation (Premium Aerotec)
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Testing of 5 Critical Load Cases
•Testing of Flap with integrated LIR
• BVID (Barely Visible Impact Damage)
• VID (Visible Impact Damage)
• NDI after Damages
• Static Loads partly with EKDF
• Fatigue Loads with LEF
BVID + NDI VID + NDI
Fatigue Phase, LEF 1,15 Damage Tolerance
Phase
3 Actuators 80 Strain gauges
Innovative Flap Load Introductions
Validation (Premium Aerotec)
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Finished Testing
• Small Delamination of Gusset Filler of DS Bracket
• Possible Delamination in inner LIR Radius
• Loads were carried despite small damages
• Fatigue Testing without further damages
Innovative Flap Load Introductions
Summary LIR
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Design and Sizing
• New Innovative Composite Design of Flap Load Introduction Rib
• Ability to analyze complex 3D Composite Parts
• Integration of effects of defects into sizing
Verification
• Verification with Risk Reduction Articels Spring Back etc.
• Verification of Preforming Abilities of all Parts
• Curing of Load Introduction Ribs with VAP Process
• QS of finished Parts
Validation
• Integration of LIR in existing A340 outbaord flap
• Fatigue and damage tolerance Testing
Over 25% Weight Reduction
Over 5% Cost Reduction
Further Investigations
CFRP Lug Sizing Rules
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CFRP Lug Sizing Rules
Motivation
• Increased use of composites in current high-lift lightweight designs
• Mostly extensive testing needed for new structural components
• => Costly: most critical several load cases are to be tested
• There are only few guidelines / designers experience
• More general approach from specific part towards common design
guidelines for high-lift structures are needed
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Comparison between FEA and Test for Composite Lugs
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50
100
150
200
250
300
350
400
450
500
1.2 1.4 1.6 1.8 2 2.2
Radius Ratio ra/ri
Fo
rce
[kN
]
FEA: QI FF
Test: QI FF
Test: QI IFF
FEA: QI IFF
Fiber Failure
Inter-Fiber Failure
Aim: General Design Rules for Lugs and Loops
CFRP Lug Sizing Rules
Approach
• Analysis of composite load introductions
(analytical and FEA)
• Validation of composite lugs and loops
• First Ply Failure / Residual Strength
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Failure Load Verification of Laminates with Lug
under 0° Loading
Test vs. FEM and Analytical Calc.
0
50
100
150
200
250
300
350
400
450
500
1,3 1,4 1,5 1,6 1,7 1,8 1,9 2
Ratio of Radius: ra/ri [ ]
Fail
ure
Lo
ad
[K
N]
Test-Lug-Failure
FEM-Lug-Failure
Analyt-Lug-Failure
Test-Lug-Non Linear
FEM-Lug-First Failure
Analyt-Lug-First Failure
Parameter study at 0° Loading
Lug vs. Loop (with and without inner ring)
0
100
200
300
400
500
600
700
1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2
Ratio of Diameter: Da/Di [ ]
Fail
ure
Lo
ad
[K
N]
FEM-Loop-Innerring-Failure
FEM-Loop-Failure
FEM-Lug-Failure
Test-Lug-Failure
0° Loading:
Loops better performance:
=> Fiber in load direction
Lugs low performance:
=> Fiber cut in load direction Parameter study at 90° Loading
Lug vs. Loop (with and without inner ring)
0
50
100
150
200
250
300
1 1,1 1,2 1,3 1,4 1,5 1,6 1,7 1,8 1,9 2
Ratio of Diameter: Da/Di [ ]
Fail
ure
Lo
ad
[K
N]
FEM-Loop-Innerring-Failure
FEM-Loop-Failure
FEM-Lug-Failure
90° Loading:
Loops low performance:
=> Matrix in load direction
Lugs low performance:
=> Fiber partly in load direction
CFRP Lug Sizing Rules
Progressive Failure Analysis of Lugs and Loops
=> AIM: Virtual Testing of Composite Lugs and Loops
• Damage Initiation using 3D Puck
• Damage evolution: failure mode dependent
– Gradual softening for inter-fiber fracture
Stiffness degradation (not E║) depending on failure mode
– Instantaneous degradation for fiber fracture, representing total structural failure
• Coupling of Fortran subroutine (including 3D Puck and degradation scheme) within every
incremental calculation of nonlinear simulation
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Analysis at every integration point
Evaluation in layers possible FF
IFF,
IFF,
0n
0n
CFRP Lug Sizing Rules
Scientific Approach (by Carolin Werchner)
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0
1000
2000
3000
4000
5000
6000
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Increments
Sh
ea
r m
od
ulu
s G
12 [
N/m
m2]
IFF FF
softening factor h degraded shear modulus G12
Verification of gradual and instantaneous
stiffness degradation
Comparison Strain Distribution:
Test vs. FEA
Test FEA
Comparison Fracture Mode
Very good qualitative accordance
But strong calibration needed
(mesh dependency etc.)
0
0.2
0.4
0.6
0.8
1
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4
Increments
So
fte
nin
g f
ac
tor
h
IFF FF
Further Investigations
Next Applications
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Next Applications
Basis: Composite 4 Bar Linkage Flap Support
• Replacement of metal carriage
• Full Composite Linkage System
• Linkages
• Brackets
• Linkages mostly as composite loops
• Lugs: thick laminate load introduction
• Failure case reduction:
• No jam of carriage
• Linkages with bearings
• Maintenance reduction
• No ball bearings
• Self lubricant bearings
• Major weight reduction
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WingFlap
Metal Track Rear Link Kinematics
Composite 4 Bar Linkage Kinematics
Next Applications
Innovative High Lift Systems for Future Aircraft
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Questions?
Thank You!
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