K.S. Raju Department of Aerospace Engineering · 2006-06-27 · The Joint Advanced Materials and Structures Center of Excellence FULL-SCALE DAMAGE TOLERANCE OF COMPOSITE SANDWICH

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)


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



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



• 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



Coupon Level Testing

Uniaxial Loading

Full-scale testing

Combined loading – Longitudinal, Hoop & pressurization.



• 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


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


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


APPROACH

DATA REDUCTION & REPORT GENERATION

TESTINGTEST ARTICLE PREPARATION

Bonding of sealsSpeckle pattern coating for DIC

FASTER, FAA WJHTC

NIAR/WSU


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


TEST ARTICLE GEOMETRY

Internal Radius : 74 inches


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]


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


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


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


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


FAILURE LOADS PREDICTION – Hostert Technical Services


TOOLING FABRICATION

COMPLETED TOOLING

FABRICATION OF TEST ARTICLES


LAYUP

MACHINING

FABRICATION OF TEST ARTICLES


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)


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


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.

Documents

K.S. Raju Department of Aerospace Engineering · 2006-06-27 · The Joint Advanced Materials and Structures Center of Excellence FULL-SCALE DAMAGE TOLERANCE OF COMPOSITE SANDWICH