Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company,for the United States Department of Energy’s National Nuclear Security Administration

under contract DE-AC04-94AL85000.

Dennis Roach, Tom Rice, Stephen Neidigk, Randy Duvall, Josh Paquette

Sandia National Labs

Results from WINDIE Experiment to Characterize Inspection Methods for Wind Blades and Use of Probability

of Detection Studies to Quantify NDI Performance

Results from WINDIE Experiment to Characterize Inspection Methods for Wind Blades and Use of Probability

of Detection Studies to Quantify NDI Performance

Blade Reliability Collaborative - ObjectiveBlade Reliability Collaborative - Objective

Nondestructive Inspection

Detectable Flaw Size

1 2 3 4 5 6 7 8 9 10

Allowable Flaw Size

Damage Tolerance1 2 3 4 5 6 7 8 9 10

Need this overlap

Required Relationship Between Structural Integrity and Inspection Sensitivity

Create the ability for manufacturers to determine the quality of their product before it leaves the factory & to

enhance the in-service inspection of wind blades

Sandia Labs Wind Turbine BladeTest Specimen Library

Sandia Labs Wind Turbine BladeTest Specimen Library

Engineered Test Specimens Wind Blade Specimens

Different Flaw Types Engineered into NDI Feedback Specimens

Different Flaw Types Engineered into NDI Feedback Specimens

Glass Beads Grease Pillow InsertMold Release

Voids in bond joint

Glass beadsIn bond joint

Dry fabric areasWaviness produced by pre-cured

resin rods

Pull tabs inbond joint

Materials inserted into multiple layers

Spar Cap and Shear WebNDI Feedback Specimen No. 2

Spar Cap and Shear WebNDI Feedback Specimen No. 2

    

                                                                  

1.01"

0.34"

1.35"

0.68"

0.67"

1.35"

0.34"

1.01"1.35"

USED VECTORPLY ELT 5500 24 PLIES OF MATERIAL (UNIAXIAL FIBER)

2.000"1.000"

2.000"

.40" (10mm) BONDLINE

INSPECTION SIDE

PERCENTAGE OF FULLTHICKNESS AT BONDLINE(.100" SKIN AND .400" BONDTHICKNESS)

25% (OF FULL THICKNESS)

50% (OF FULL THICKNESS)

75% (OF FULL THICKNESS)FLAT BOTTOM HOLE (FBH)

PILLOW INSERT

EXAMPLES OF VARIOUS FLAW DEPTHS IN SPAR CAP SECTION

INSPECTION SURFACE

NDI REFERENCE STANDARD 2 FABRICATION DRAWING SPAR CAP AND SHEAR WEB BLADE SCHEMATIC

(DISBONDS IN ADHESIVE)PULL TABS

(DELAMS) (DELAMS) (BASED ON 24 PLIES OF UNIAXIAL MAT'L)(DISBONDS IN ADHESIVE)

25%(.125" MR)

50%(.25" MR)

1.00" DIA

2.00" DIA

SHEAR WEB

ADHESIVE

FLAT BOTTOM HOLES

1.00" (25mm) FOAM CORE

INTERFACE 2

INTERFACE 1

INTERFACE 1

25%(B/W PLIES 18 & 19)

75%(B/W PLIES 6 & 7)

75%(.375" MR)

4 PLY PILLOW INSERTSFLAT BOTTOM HOLES

25% (B/W PLIES18 & 19)

50% (B/W PLIES12 & 13)

75% (B/W PLIES6 & 7)

25% (.34" MR)50% (.68" MR)75% (1.01" MR)

2.00" DIA

.50" DIA

1.00" DIA1.50" DIA

1.50" DIA 1.00" DIA

.50" DIA

2.00" DIA

2.00" DIA

.50" DIA

1.00" DIA1.50" DIA

1.50" DIA 1.00" DIA

.50" DIA

2.00" DIA

2.00" DIA

1.50" DIA

1.00" DIA

.50" DIA

.50" DIA

1.00" DIA

1.50" DIA

2.00" DIA

18.00"

~1.35" (34mm) UNIAXIAL (SPANWISE)

30.00"

__(+45, +45)2 PLIES OF DOUBLE BIAS (DB)

2 PLIES OF DOUBLE BIAS (DB)

11-30-10

MR = MATERIAL REMAINING

PLY NO. 1 OF SPAR CAP

2 PLIES OF DOUBLE BIAS (DB)

(+45, +45)_ _

__(+45, +45)

(NOTE: IF USING TEFLON BASED RELEASE FABRIC WHEN CURING MAIN SPAR, BE SURE TO LIGHTLY SAND SURFACE AREA WHERE SHEAR WEB BONDWILL TAKE PLACE) 0.60"-1.00"

2.500"

(BASED ON 24 PLIES OF UNIAXIAL MAT'L)NOTE: PULL TABS (.007" THK) WILL EXTEND OUT FROM SPECIMENEDGE DURING CURE PROCESS, BE SURE TO USE SPECIALCARE NOT TO PUNCTURE VACUUM BAG (COVER SHARPEDGES WITH BREATHER FABRIC) . PULL TABS REMOVED AFTER CURE PROCESS.

1 of 2NOTES:

1. SPECIMEN CURED USING 14 IN. HG. VACUUM PRESSURE AND VACUUM LEFT ON OVER NIGHT.

2. POST CURE SPECIMEN AT 70 C FOR 10 HOURS.

3. FINAL FLAT BOTTOM HOLE DEPTH MAY CHANGE DEPENDING ON FINAL PART THICKNESS.

1.875"

2.750"

2.750"

2.750"

2.750"

2.750"

(41)

(42)

(43)

(44)

(45)

(46)

(52)(51)

(50)(49)(48)

(47)

(53)(54)

(55) (56)(57)

(58)

(64)

(63)

(62)

(61)

(60)

(59)

(65) (66) (67) (68)

(69)

(70)

(71)

(72)

(73)

(74)

(75)

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(77)

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(80)

Flaw types to include: snowflaking, porosity, resin-starved regions, voids, interply delaminations, spar and shear web disbonds, ply waviness

75% MR

Depth into adhesive & shear web skin

50% MR

25% MR

NDI Feedback Specimens 1, 2 & 4 –Shear Web & Foam Core Specimens

NDI Feedback Specimens 1, 2 & 4 –Shear Web & Foam Core Specimens

Laminate with Waviness and Dry Regions

Foam Core with Disbonds and Delaminations

Shear Web/Spar with Disbonds and Delaminations

Ultrasonic Deployment ProgressionUltrasonic Deployment Progression

Single Element Transducer varying Diameter • 500 KHz, 1 MHz, 1.5 MHz

Linear Encoded Phased Array• 500 KHz,1 MHz, 1.5 MHz• Multiple linear encoders• 16, 32, 42 and 64 Elements• 5 to 10 Water Box options

Automated and Semi-Automated X-Y Scanning• MAUS V Automated Scanner• OmniScan X-Y Glider• Marrietta Automated Scanner

On-Blade Phased Array UT InspectionsOn-Blade Phased Array UT Inspections

16 Meter Station on Fiberglass Spar Cap Blade

Spar Cap Cross Section Schematic Showing the Spar Cap, Adhesive

Bond Line and Shear Webs

Scanning Direction

Sealed water box and 1.5L16 Phased Array probe was used to detect missing adhesive in bond lines

Vertical Strip C-Scan Image Showing Adhesive Void in

Upper Bond Line

Adhesive Void Between Spar

Cap and Shear Web

Wind Inspection NDI Experiment (WINDIE) - Advanced NDI Vendor Participation

Wind Inspection NDI Experiment (WINDIE) - Advanced NDI Vendor Participation

Advanced NDI Methods for Wind Turbine Blades

Over 30 agencies invited22 accepted invitation

Report completed detailing advanced NDI screening

Completed

Experiments

with

22 Agencie

s

Inspection Method CompanyP Linear Array UT 3D Matrix Eye ToshibaP Phased Array UT Olympus NDT

Acoustic Emission iHMSiP Air Coupled UT ISU

ANDSCAN-Robot Genesis SystemsBandicoot CSIRO

Custom Systems ExovaP Digital Acoustic Video (Acoustacam) Imperium

Digital Image Correlation (DIC) Dantec DynamicsFlaw Inspecta UT Array NDT Solutions Inc

P Focused Probe Immersion UT GE Inspection TechnologiesGuided Ultrasonics Guided Ultrasonics

P Induction Thermography System & Air Coupled UT BoeingInduction Thermography System (ITS) Quest Integrated Inc

P IR Inspection Ssytem (IRIS) Vista Engineering TechnologiesLaminography Digiray

P Laser UT iPhotonLine Thermography Mistras Group

Linear Array UT USUT Labs/VeracityP Lock-In Thermography moviMED/MoviTherm

MAUS MIA Mode AANCMAUS Resonance Mode AANC

P Microwave GE Global ResearchP Microwave NDE EvisiveP Millimeter Wave Inspection Tool Physical Optics Corp. (POC)P Phased Array UT AANC

Pulse Echo UT QinetiQP RapidScan2 (Phased Array Wheel Probe) Sonatest/R-CON NDT

Rotor Blade CT System iHMSiP Shearography Dantec Dynamics

Shearography Laser Technology IncSonic IR WSUTerahertz Teraview

P Terahertz Radiation (T-Ray) Iowa State UniversityTerrahertz Imaging GMA Industries

Thermography AANCP Thermography Thermal Wave ImagingP Through Transmission AANC

Ties to QinetiQ Triton SystemsP TSCOUT (Thick Section Comp. UT) & PAC UT Mistras Group

UT and IR Systems TecScanUT Spectroscopy QinetiQ

Various NDI IHI Southwest TechnologiesP Vibro Thermography ResodyneP MAUS Phased Array UT AANCP RotoArray - Phased Array UT GE Inspection Technologies

WINDIE – Advanced NDI Screening ActivityWINDIE – Advanced NDI Screening Activity

• Flaw detection peformance (type, sensitivity)• Duration of inspection• Fieldability (contact/noncontact)• Deployment issues• Inspection difficulties• Cost of new system• Accessories needed to make fieldable• Ease of data interpretation

Information gathered during round-robin inspections:

REF-STD-4-135-SNL-1(wrinkles & dry areas)

REF-STD-2-127-173-SNL-1

WINDIE – Specimens Used for NDI ComparisonWINDIE – Specimens Used for NDI Comparison

Phased/Linear Array Ultrasonics Phased/Linear Array Ultrasonics

Toshiba MatrixEyeOlympus OmniScan

• Ultrasonic probes consists of 16 to 256 individual elements• Can produce A, B, and C-scans• Low frequency (0.5 to 1.5 MHz) for deep penetration • Multiple deployment options

Sandia LabsMethod: MAUS V PE Focus Probe

with Water Column

Sandia LabsMethod: Phased Array UT

25mm Water Box

Phased Array UT – Display and DeploymentPhased Array UT – Display and Deployment

Olympus 1.5Mhz, 42 element probe

Sonatest RapidScan 2

GE Phased Array UT RotoArray

ShearographyShearography

Sandwich core specimenThick laminate with bond lines

• Uses vacuum, heat, vibration to monitor the surface of a structure for changes in the surface strain field/displacement

• Wide area interferometric imaging technique that is capable of detecting micron-sized displacements

ThermographyThermography

• Thermography relies on the heat absorption characteristics of the structure and changing IR images/heat transfer curves to indicate the presence of defects

Terahertz RadiationTerahertz Radiation

C-scans gated around the returning time of flaw sets

PILLOW INSERTS

MICRO-BALLOONS

PULL TABS

2.00" DIA. 1.50" DIA. 1.00" DIA. .50" DIA.

Test specimen flaw profile

• 50 GHz – 4 THz frequency range with air-coupled, high penetration• Flaws detected through frequency attenuation, phase shift and time of

flight • Changes in THz signatures can indicate degradation of material as well• Pitch-catch mode allows for single-sided inspections

Time gate rangeTime gate range

??

740 X 400 @ 1.5mm

WINDIE Technology Assessment WINDIE Technology Assessment

Improved flaw detection: Advanced NDI Hybrid inspection approach - stack multiple

methods which address array of flaw types (data fusion)

Tom Rice, Dennis Roach, Stephen Neidigk, Randy Duvall and Josh Paquette

Sandia National Labs Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security

Administration under contract DE-AC04-94AL85000

Wind Turbine Blade Flaw Detection ExperimentWind Turbine Blade Flaw Detection Experiment

Wind EnergyBlade Reliability Collaborative (BRC)

 Detection of Hidden

Flaws in Composite Wind Turbine Blade Structure

Purpose• Generate industry-wide performance curves to quantify:

how well current inspection techniques are able to reliably find flaws in wind turbine blades (industry baseline)

the degree of improvements possible through integrating more advanced NDI techniques and procedures.

Expected Results - evaluate performance attributes 1) accuracy & sensitivity (hits, misses, false calls, sizing) 2) versatility, portability, complexity, inspection time (human factors) 3) produce guideline documents to improve inspections 4) introduce advanced NDI where warranted

An Experiment to Assess Flaw Detection Performance in Wind Turbine Blades (POD)

An Experiment to Assess Flaw Detection Performance in Wind Turbine Blades (POD)

Wind Blade NDI Probability of Detection ExperimentWind Blade NDI Probability of Detection Experiment

- Blind experiment: type, location and size of flaws are not know by inspector- Statistically relevant flaw distribution – Probability of Detection (POD)- Used to analytically determine the performance of NDI techniques – hits,

misses, false-calls, flaw sizing, human factors, procedures

Experimental Design Parameters• Representative design and manufacturing• Various parts of blade such as spar cap,

bonded joints, leading and trailing edge• Statistically valid POD (number, size of flaws

and inspection area)• Random flaw location• Two days to perform experiment• Deployment

Fabrication Considerations• Realistic, random flaw locations• Portable sample set• Range of thickness• Material types (fiberglass, carbon and various

adhesives)• Who will manufacture

Spar Caps & Shear Web Box Spar & Shear Webs

Designed to be applicable to various blade construction

An Experiment to Assess Flaw Detection Performance in Aircraft Composite Structures

An Experiment to Assess Flaw Detection Performance in Aircraft Composite Structures

737 Composite Horiz. Stabilizer

A380 Fuselage Section 19

Thickness Range:12 – 64 plies

Simple Tapers

Complex tapers

Substructure Flaws

Curved Surfaces

Array of flaw types

Solid Laminate ExperimentSample Participants

Solid Laminate ExperimentSample Participants

Solid Laminate Flaw Detection Experiment Implementation

Solid Laminate Flaw Detection Experiment Implementation

PODs calculated for overall laminate, by thickness family, by substructure effects, by complex geometry effects, by flaw types, etc.

POD Curves for 20-32 Ply Solid Laminate Family

POD Curves for 20-32 Ply Solid Laminate Family

False Calls: Constant thickness = 0.8/inspectorComplex Geometry = 0.3/inspector

12 ft.2 inspection area

Overall: POD[90/95] = 0.82” dia.

Individual and Cumulative Comparisons

Flaw Size (Diameter in Inches)

Pro

bab

ilit

y o

f D

etec

tio

n What improvements will advanced NDI provide?

Thermography

Wind Blade Probability of Detection ExperimentWind Blade Probability of Detection Experiment

First design iteration of POD experiment 2012

NRELUpWind

DOEClipper

LM Wind PowerGamesa

Molded FiberglassSNL

TPI CompositesGE – Global Research

VestasSandia

Review Committee

Second iteration incorporating review committee’s suggestions

Ensure representative blade construction and materials

Specimens fabricated, characterized and ready(11 specimens)

What We Need• Qualified Inspectors

Wind blade manufacturing companies Blade service companies Wind farms NDI equipment development labs

• 2-2½ days of your time

Wind Blade Probability of Detection ExperimentWind Blade Probability of Detection Experiment

How Does This Benefit You?• Training perspective, inspections on representative blade

structure• Inspector will receive feedback on how they performed

• PoD Value, smallest flaw size detectable with 95% confidence

• Number of flaws detected• Number of flaws missed• Number of false calls, if any• Flaw sizing• Location and type of flaws missed

Wind POD Experiment is UNDERWAYWind POD Experiment is UNDERWAY

Completed fabrication of 11 POD Specimens

• 11 POD specimens with spar cap and shear web geometry• Thickness ranges from 8 Plies (0.45” thick laminate, 0.85” thick with

adhesive bond line) to 32 Plies (1.80” thick laminate, 2.20” thick with adhesive bond line)

• All panels painted with wind turbine blade paint (match inspection surface)

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0.2

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0 0.5 1 1.5 2 2.5 3

Pro

ba

bil

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of

De

tec

tio

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Flaw Size (Diameter in Inches)

Example Wind POD Curve - All Flaws - All Construction Types

POD Maximum Likelihood Estimate

POD Uncertainty - 95% Confindence Bound

If you are interested in participating in this experiment or have other questions, please contact me using the following:

Tom RicePhone: (505) 844-7738Email: tmrice@sandia.gov

Wind Blade Probability of Detection ExperimentWind Blade Probability of Detection Experiment