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The Joint Advanced Materials and Structures Center of Excellence
FFULLULL--SSCALE CALE DDAMAGE AMAGE TTOLERANCE OF OLERANCE OF CCOMPOSITE OMPOSITE SSANDWICH ANDWICH SSTRUCTURESTRUCTURES
K.S. RajuK.S. RajuDepartment of Aerospace EngineeringDepartment of Aerospace Engineering
2The Joint Advanced Materials and Structures Center of Excellence
FAA Sponsored Project Information
• Principal Investigators & Researchers– J.S. Tomblin– K.S. Raju, J. Dietiker, J.F. Acosta– J. Bakuckas
• FAA Technical Monitor– P. Shyprykevich
• Other FAA Personnel Involved– C. Davis– F. Leone
• Industry Participation– Adam Aircraft Co.( P. Harter, B. Allbritten)– Toray Composites ( L. Cook)– NSE Composites ( T. Walker)– Hostert Technical Services ( R. Hostert)
3The Joint Advanced Materials and Structures Center of Excellence
FULLFULL--SCALE DAMAGE TOLERANCE OF SCALE DAMAGE TOLERANCE OF COMPOSITE SANDWICH STRUCTURESCOMPOSITE SANDWICH STRUCTURES
Background
REPORTS-DOT/FAA/AR-99/49, 1999 DOT/FAA/AR-00/44, 2001 DOT/FAA/AR-02/80, 2002 DOT/FAA/AR-02/121, 2003 DOT/FAA/AR-03/75, 2004 DOT/FAA/AR-0?/??, 2005
Literature Review
Experimental Investigation of Damage Resistance & Tolerance
NDI Techniques, Curvature effects, Fatigue
Scaling effects
Open-Hole TestingIndependent Review
1998
1999
2004
2001
Design of experiments, CAI modeling
4The Joint Advanced Materials and Structures Center of Excellence
FULLFULL--SCALE DAMAGE TOLERANCE OF SCALE DAMAGE TOLERANCE OF COMPOSITE SANDWICH STRUCTURESCOMPOSITE SANDWICH STRUCTURES
0 1 2 3 4 5 6
TTU C-Scan Planar Damage Diameter 2Rdamage (in)
0
0.2
0.4
0.6
0.8
1
1.2
Nor
mal
ized
CA
I Stre
ngth
[(90/45)n/ CORE]S
SKIN : NB321/3K70 PWCFCORE : Plascore PN2-3/16-3.0
IMPACTOR DIAMETER1.00"3.00"
Strength Degradation Curve NCAI = f(2Rdamage)
Range of hole diameters selected for study
ORIGINAL DAMAGE AREA
INCREASE IN DIMPLE DEPTH CRACK INITIATION
CRACK PROPAGATION- FINAL FAILURE
A A'y
x
x
yA A'
ORIGINAL DAMAGE AREA DIMPLE GROWTH (POINT A) DIMPLE ARREST (POINT B)UNSTABLE DIMPLE GROWTH-FINAL FAILURE (POINT C)
RMAXΔ
RESIDUAL INDENTATION
2R
damage2R
ind
5The Joint Advanced Materials and Structures Center of Excellence
FULLFULL--SCALE DAMAGE TOLERANCE OF SCALE DAMAGE TOLERANCE OF COMPOSITE SANDWICH STRUCTURESCOMPOSITE SANDWICH STRUCTURES
• Critical Damage States – IMPACT DAMAGE – Load
transfer through damage region
– OPEN HOLE – No load transfer through damage region
0 1 2 3 4 5 6PLANAR DAMAGE DIAMETER 2RDAMAGE (INCHES)
0
0.2
0.4
0.6
0.8
1
1.2
NO
RM
ALI
ZED
RE
SID
UA
L C
OM
PR
ES
SIV
E S
TRE
NG
TH
OPEN HOLE Whitney-Nuissmer average stress criterionao = 0.15"
IMPACT DATA [Newport]IMPACT DATA [Toray]
The size of the circles corresponding to the open hole data indicate the facesheet thickness. The smallest correponds to2 plies and the largest corresponds to 6 plies.
θ
FRONT BACK
θ
FRACTURE
OUTWARD BUCKLING
FRONT BACK
0 1 2 3 4 5HOLE DIAMETER 2RHOLE (inches)
0
1000
2000
3000
4000
5000
STR
ENG
TH
|Nyy
| (lb
f/in)
[(90/45)2/ CORE]S PANELS
HOLE TYPE / LOADINGSINGLE FACESHEET / TENSIONTHROUGH / TENSIONNONE / TENSIONSINGLE FACESHEET / COMPRESSIONTHROUGH / COMPRESSIONNONE / COMPRESSION
6The Joint Advanced Materials and Structures Center of Excellence
FULLFULL--SCALE DAMAGE TOLERANCE OF SCALE DAMAGE TOLERANCE OF COMPOSITE SANDWICH STRUCTURESCOMPOSITE SANDWICH STRUCTURES
Coupon Level Testing
Uniaxial Loading
Full-scale testing
Combined loading – Longitudinal, Hoop & pressurization.
7The Joint Advanced Materials and Structures Center of Excellence
FULLFULL--SCALE DAMAGE TOLERANCE OF SCALE DAMAGE TOLERANCE OF COMPOSITE SANDWICH STRUCTURESCOMPOSITE SANDWICH STRUCTURES
• Objectives– Design, fabrication & Testing of sandwich test article(s)
under combined loading at WJHTC test facility• Material Systems & Sandwich Configuration• Geometry• Load-introduction
– Attachments,etc.• Damage configurations – notches, holes, impact damage, etc..• Instrumentation • Loading Scenarios• Failure load predictions • Testing
8The Joint Advanced Materials and Structures Center of Excellence
APPROACH
ESTIMATE FAILURE LOADS
REVIEW PREVIOUS TESTARTICLES/REPORTS
STUDY TEST FIXTURE CAPABILITIES/FEATURES
FEA ANALYSIS- Hostert Technical Services
MEETINGS WITH FASTER FACILITY ( Dr. Backuckas)
TEST ARTICLE DESIGN1. GEOMETRY2. MATERIAL SYSTEMS3. LOAD INTRODUCTION4. DAMAGE TYPE
DOT/FAA/AR-99/49, 1999 DOT/FAA/AR-00/44, 2001 DOT/FAA/AR-02/80, 2002 DOT/FAA/AR-02/121, 2003 DOT/FAA/AR-03/75, 2004
NIAR/WSUFAA WJHTC
NIAR/WSU
9The Joint Advanced Materials and Structures Center of Excellence
APPROACH
INSTRUMENTATION OF TEST ARTICLE
- STRAIN GAGES
TEST ARTICLE FABRICATION1. MOLD DESIGN & FABRICATION2. TEST ARTICLE FABRICATION3. MACHINING4. INSPECTION
ADAM AIRCRAFT Co.
NIAR/WSU
PANELS SHIPPED TO NIAR/WSU
10The Joint Advanced Materials and Structures Center of Excellence
APPROACH
DATA REDUCTION & REPORT GENERATION
TESTINGTEST ARTICLE PREPARATION
Bonding of sealsSpeckle pattern coating for DIC
FASTER, FAA WJHTC
NIAR/WSU
11The Joint Advanced Materials and Structures Center of Excellence
Full-Scale Aircraft Structural Test Evaluation & Research (FASTER) Fixture
Ref. John Bakuckas, “Full-Scale Testing and Analysis of Fuselage Structurecontaining Multiple Cracks,” DOT/FAA/AR-01/46.
TEST FIXTURE SPECIFICATIONSRef
• Longitudinal loading – 1800 lbf/in– 16 load introduction points
• Circumferential (Reactive) loading– 1800 lbf/in– 28 load introduction points
• Frame Loads– 360 lbf/in
• Pressurization loading– 15 psi– Water / Air
• SPECIMEN GEOMETRY– Radius : 60 – 130 inches ( ** 74 inches)– Length : 120 inches– Width : 68 inches
12The Joint Advanced Materials and Structures Center of Excellence
TEST ARTICLE GEOMETRY
Internal Radius : 74 inches
13The Joint Advanced Materials and Structures Center of Excellence
TEST ARTICLE
• Material Systems– Facesheet
• TORAY COMPOSITES T700SC-12K-50C/#2510 PWCF
– Core • Plascore Nomex PN2-3/16-3.0 honeycomb (0.75 in thick)
• Sandwich Configuration (test section)• [45/0/45/core/45/0/45]
14The Joint Advanced Materials and Structures Center of Excellence
TEST ARTICLE
ALL DIMENSIONS IN inches
90°
0°
PN2-3/16-3.0 HONEY COMB CORE 0.75 THICK
PN2-3/16-3.0 HONEY COMB CORE TAPER REGION
PN2-3/16-3.0 POTTED HONEY COMB CORE 0.375 THICK
A A
0.7500.375
1.5
POTTED CORE
VIEW A-A
15The Joint Advanced Materials and Structures Center of Excellence
TEST ARTICLE
ALL DIMENSIONS IN inches
C C0°
90°
REGION - AREGION - B
REGION - C
REGION - D
10.50
9.50
452
0
0450
450
45
452
0
FILM ADHESIVECORE
45
LC
VIEW C-C
STACKING SEQUENCE LAYOUT
16The Joint Advanced Materials and Structures Center of Excellence
DAMAGE CONFIGURATIONS
27.5033.00
56.0066.00
112.00LC
CL
120.00
53.50
60.00
90°
0°Ø10.00
12.0
GAGES 13,[14] (0°)GAGES 15,[16] (90°)
GAGES 17,[18] (0°)GAGES 19,[20] (90°)
GAGES 25,26,[27],[28]
GAGES 29,30, [31],[32]
GAGES X, [Y]
CONVEX SIDE (FRONT) CONCAVE SIDE (BACK)
12.0
24.0
GAGES 5,[6] (0°)GAGES 7,[8] (90°)
GAGES 1,[2] (0°)GAGES 3,[4] (90°)
GAGES 9,[10] (0°)GAGES 11,[12] (90°)
12.0GAGES 21,[22] (0°)GAGES 23,[24] (90°)
24.0
66.00 56.00
33.00
112.00
LC
CL
0°
120.0060.00
10.00
0.5
24.0
12.0 24.0
12.0
12.0
CONCAVE SIDE (BACK)
GAGES X, [Y]
CONVEX SIDE (FRONT)
90°
GAGES 1,[2] (0°)GAGES 3,[4] (90°)
GAGES 5,[6] (0°)GAGES 7,[8] (90°)
GAGES 9,[10] (0°)GAGES 11,[12] (90°)
GAGES 13,[14] (0°)GAGES 15,[16] (90°)
GAGES 17,[18] (0°)GAGES 19,[20] (90°)
GAGES 21,[22] (0°)GAGES 23,[24] (90°)
GAGES 25, 26, [27], [28] (0°)
120.00
112.00
33.00
66.00 56.00
60.00
CL
90°
0°
LC
0.5
10.00GAGES 5,[6] (0°)GAGES 7,[8] (90°)
GAGES 1,[2] (0°)GAGES 3,[4] (90°)
24.0
12.0
GAGES 9,[10] (0°)GAGES 11,[12] (90°)
12.0
12.0
GAGES 13,[14] (0°)GAGES 15,[16] (90°)
24.0
GAGES 21,[22] (0°)GAGES 23,[24] (90°)
GAGES 17,[18] (0°)GAGES 19,[20] (90°)
CONVEX SIDE (FRONT)
GAGES X, [Y]
CONCAVE SIDE (BACK)
GAGES 25, 26, [27], [28] (0°)
5.00
0.50
0.25
GAGE 25 [27]
GAGE 26 [28]
5.00
GAGE 26 [28]GAGE 25 [27]
0.25
0.50
CIRCUMFERENTIAL NOTCH
LONGITUDINAL NOTCH
R0.25
R0.25
17The Joint Advanced Materials and Structures Center of Excellence
TEST MATRIX
LOADING TYPE TEST CASE
No.
DAMAGE TYPE
LOAD CASE
No. Longitudinal loads
Pressurization loads
Longitudinal + Pressurization
Loads
1A X 1B X 1. None
1C X 2A X 2B X 2.
10” diameter hole in top facesheet
2C X
3A X 3.
10” Longitudinal Notch (a/b = 20) 3B X
4A X 4.
10” circumferential Notch (a/b = 20) 4B X
NOT LOADED TO FAILURE
18The Joint Advanced Materials and Structures Center of Excellence
FAILURE LOADS PREDICTION – Hostert Technical Services
19The Joint Advanced Materials and Structures Center of Excellence
TOOLING FABRICATION
COMPLETED TOOLING
FABRICATION OF TEST ARTICLES
20The Joint Advanced Materials and Structures Center of Excellence
LAYUP
MACHINING
FABRICATION OF TEST ARTICLES
21The Joint Advanced Materials and Structures Center of Excellence
TEST ARTICLE FABRICATION STATUS
• First Test panel delivered to NIAR/WSU – Jan 2006– Panel without hole/notch– Test article bonded with strain gages at NIAR/WSU– Test article shipped to FAA WJHTC – 2nd week of Feb 2006
• Fabrication of test panels with hole and notches under progress ( 06/01/2006)– Panel with circumferential notch – layup under progress
• Shipped to WSU 7/10– Panel with longitudinal notch – machining completed
• Shipped to WSU 7/10– Panel with hole – layup under progress
• Manufacturing defects ( wrinkles)
22The Joint Advanced Materials and Structures Center of Excellence
TESTING : STATUS/SCHEDULE
• Pressure seals acquired by NIAR /WSU – Dec 2005 – Jan 2006– Pressure seal shipped to FAA WJHTC – 3rd week of February 2006
• July 10, 2006 – Receive panels (notched) from Adam Aircraft Co., – Strain gaging ( ~ 2 weeks)
• July 30, 2006- Ship panels( notched) and pressure seals to FAA WJHTC
• July 20, 2006- Receive panel ( open hole) from Adam Aircraft Co., – Strain gaging ( ~ 2 weeks)
• August 10, 2006- Ship panels( open-hole) and pressure seals to FAA WJHTC
• August 15, 2006 - First panel installed – August 15 – September 30, 2006 – testing of panels
23The Joint Advanced Materials and Structures Center of Excellence
A Look Forward
• Future needs– Longitudinal compression loading capability in the
fixture– Inclusion of shear loading– Fatigue– Structural details – cut-outs, adhesive joints, etc.– Other damage types – Impact damage, Lightening
strike, off-axis notches, etc.