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, Josh PaquetteWind Blade Reliability Center
Sandia National Labs
Optimizing Quality Assurance Inspections to Improve the Probability of
Damage Detection in Wind Turbine Blades
Blade Reliability Collaborative – NDI Objectives
• Develop, evaluate and validate the array of potential nondestructive inspection methods for the detection of flaws in composite wind turbine blades
• Plan and implement a national capability – including a physical presence and methodology - to comprehensively evaluate blade inspection techniques
• Produce optimum deployment of automated or semi-automated NDI to detect undesirable flaws in blades (time, cost, sensitivity)
• Transfer technology to industry through hardware and technology evaluation, inspector training, and procedure development
Create the ability for manufacturers to determine the quality of their product before it leaves the factory & to enhance the
in-service inspection of blades for wind farm operators
Optimized InspectionsTraining
Inspectors,Equipment, &
NDI Techniques
Procedures
NDI Calibration &Reference Standards
BladeMaintenance
Programs
Blade Reliability Collaborative -Program Thrusts to Improve Wind NDI
Enhance factory reliability, facilitate repairs before acritical is reached, minimize turbine downtime & increase blade lifetime
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
VoidsVoids
Inspection Areas and Flaw Types of Interest
Flaws include: Ply Waves Delaminations, Adhesive Voids, Joint Disbonds, Snowflaking and Porosity
Ultrasonic Transducer
Captured Water Column
Scanning Shoe for Offset of UT Wave
Plastic Membrane
Weeper Body
Water Inlet(pumped in from reservoir)
Water Couplant Pool
Inspection Surface
Excess Water Flow(recovered into reservoir)
To Data Acquisition System
MAUS P-E UT with Focused Probe (1 MHz/2”) and Adjustable Water Path
New “Immersion” Probe Holder
Allows for Adjustable Water Path
Flat Bottom HolesPillow Inserts
Pull TabsREF-STD-6-202-250-SNL-1
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" DIA 1.50" DIA
1.50" DIA 1.00" DIA
.50" DIA2.00" DIA
2.00" DIA
.50" DIA
1.00" DIA 1.50" 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)
(76)
(77)
(78)
(79)
(80)
Tapered Adhesive Wedge Fiberglass Inspection Surface
Adhesive Bond Line
Out of Spec Thickness
Develop and assess methods to inspect bond line thickness
Phased Array UT Results
Good Bond Line Thickness
Anomalies in Bond Line
Adhesive Thickness Measurements with Phased Array UT
Phased Array UT – Display and Deployment
Olympus 1.5Mhz, 42 element probe
Sonatest RapidScan 2
GE Phased Array UT RotoArray
On-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
Purpose• Generate industry-wide performance curves to quantify:
Ø how well current inspection techniques are able to reliably find flaws in wind turbine blades (industry baseline)
Ø the degree of improvements possible through integrating more advanced NDI techniques and procedures.
An Experiment to Assess Flaw Detection Performance in Wind Turbine Blades (POD)
Expected Results - evaluate performance attributes1) accuracy & sensitivity (hits, misses, false calls, sizing)2) versatility, portability, complexity, inspection time (human factors)3) produce guideline documents to improve inspections4) introduce advanced NDI to industry
Wind 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• Maximum of two days to perform experiment• Deployment
Fabrication Considerations• Realistic, random flaw locations• Portable sample set• Range of thickness• Material types (fiberglass and adhesives)
Spar Caps & Shear Web Box Beam
Specimens designs applicable to various blade construction
Wind Blade Flaw Detection Experiment -Probability of Detection Experiment
Benefit to Participants• Training perspective, inspections on representative
blade structure• Inspector and production facility received feedback on
how they performed• POD Value, smallest flaw size detectable with 95%
confidence• Number of flaws detected & missed• Number of false calls, if any• Flaw sizing• Location and type of flaws missed
NRELUpWind
DOEClipper
LM Wind PowerGamesa
Molded FiberglassSNL
TPI CompositesGE – Global Research
VestasSandia
Review Committee
Ensure representative bladeconstruction and materials
POD Specimen Development and Characterization
Laminate Flaws Include:Pillow Inserts
Grease ContaminateWrinkles – Dry stacked plies
Dry AreasFlat Bottom Holes
Glass Microballoons
Bond Line Flaws Include:Pillow Inserts
Pull TabsFlat Bottom Holes
VoidsGlass Microballoons
Phased Array UT 40mm Water Box Scan
Implementation of Wind POD Experiment
• 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)
Wind Blade Flaw Detection Experiment – Individual Inspector and Cumulative POD Comparison
All Panels - Spar Cap with Shear Web and Box Spar Construction Types
Conventional Single Element Pulse-Echo Ultrasonic Inspection Method
Wind Blade Flaw Detection Experiment – Various NDI Performance Attributes Evaluated
Spar Cap with Shear Web and
Box Spar Construction Types
Spar Cap with Shear Web
Construction Types
All Panels - Constant Thickness Flaws
All Panels - Complex Geometry Flaws
Wind Blade Flaw Detection Experiment –Improvements Produced by Use of Advanced NDI
C-scan images produced by single-
element ultrasonic scanner systems –
easier to interpret data
All Panels, All Flaw Types –Conventional NDI
POD 90/95 = 1.333
All Panels, All Flaw Types –Advanced NDI(example only)
POD 90/95 = 1.105
Results from Single-Element UT Scanner System
Wind Blade Flaw Detection Experiment –Optimizing Results with Proper Analysis
Non-optimal use of gate settings can allow damage to go undetected
Initial Results -flaw under bondline is
not imaged
Inspector BB – 2” Flaw “Miss” is changed to a “Hit”(additional data gates used to detect deeper flaws)
Second Analysis – data reviewed using additional gate settings; damage detected
• Need to develop array of inspection tools to comprehensively assess blade integrity
• Consider time, cost, & sensitivity issues (minimize production, maintenance and operation costs)
• Develop NDI solutions in concert with related studies: effects of defects, field surveys, analysis, certification, standards
• NDI investigation has produced promising results thus far & may lead to hybrid approach with multiple NDI tools (e.g. near surface and deep flaws)
• There are sensitive & rapid NDI options available for inspecting wind blades, both for manufacturing QA and in-service NDI
• Evolution in phased array UT methods & use of C-scan technology provides the greatest & easiest-to-achieve benefits
• Training, experience (apprenticeships) and optimized procedures are key factors in determining the overall performance of NDI for detecting flaws/damage in wind blades
• NDI can help ensure that wind blades meet their design life and possibly beyond
Wind Blade Flaw Detection Experiment –Steps to Improve Probability of Flaw Detection
If you are interested in participating in the Sandia Labs wind blade inspection activities:
Tom RicePhone: (505) 844-7738Email: [email protected]
Dennis RoachPhone: (505) 844-6078Email: [email protected]
Ray ElyPhone: (505) 284-9050Email: [email protected]
Optimizing Quality Assurance Inspections to Improve the Probability of
Damage Detection in Wind Turbine Blades
Top Related