Implementation of Transient Eddy Currents from Lab Bench to the Production Environment

Transcription

1 Implementation of Transient Eddy Currents from Lab Bench to the Production Environment Jesse A. Skramstad, NDT Solutions, Inc. Robert A Smith, QinetiQ Ltd UK Lt Gary Steffes and Charles Buynak, USAF, AFRL, Materials and Manufacturing Directorate ASIP DECEMBER, 2004

2 What is TRECSCAN? TRECSCAN is a Transient Eddy Current Inspection System Developed by QinetiQ Ltd. (DERA UK) Time Domain Eddy Current Unique Analysis Software that Includes: Edge Subtraction Lift-Off Compensation Total Thickness Measurement Plate Separation Effect Elimination

3 Why Is TRECSCAN Different? TRECSCAN Uses a Hall sensor as a field detector instead of a coil Eddy current pulses are generated using a coil and the Magnetic Field is measured directly using a Hall sensor TRECSCAN measures and captures the complete transient data set

4 What is a Hall Sensor? A Hall sensor is semi conductive platelet, when a small current is passed through it, a Hall voltage is generated by the effect of an external magnetic field acting perpendicularly to the direction of the current.

5 Advantages Of Using Hall Sensors Hall sensors respond to a wide frequency range allowing the capture of detailed transient data sets. Hall sensors provide direct measurement of the magnetic field, essential for the application of analytical theory to the transient data. Hall sensors used as a field detectors rather than coils, improve the spatial resolution and the detectability of deep defects.

6 The Transient Eddy Current Method Coil Current i input current i(t) time t i(t) H z (t) Magnetic Field Hz H z (air) H z (specimen) H z (defect) time t H R z = H z (specimen) - H z (air) Ferrite core Drive coil Hall effect sensor First layer Gap Second layer Corrosion Graphic courtesy QinetiQ

7 Transient Eddy-Currents Eddy-current pulses Hall Sensor Drive Coil Depth Time Graphic courtesy QinetiQ

8 Transient Eddy-Current Signal Magnetic field Transient signals from structural changes at different depths Time (ms)

9 Transient Data Storage Time-slices Separate C-scan images can be produced from each time-slice. TRECSCAN stores the transient response at an exponentially distributed sequence of time points. This Time-slice data is saved at each probe position, permitting recreating the scan and post processing of the data after acquisition.

10 Unique Post Analysis Tools Lift-off Compensation Edge Subtraction Total Thickness Measurement Time-slice viewing Time Domain Signal Processing Time to Peak Measurement

11 Lift-Off Problem 1.80 mm (0.071 ) 3) 2) 1.14 mm (0.045 ) or 0.83 mm (0.032 ) 1) 1.60 mm (0.063 ) 4) 5) 1.91 mm (0.075 ) or 3.18 mm (0.125 ) Probe Tapered and stepped 1.5 mm (0.060 ) to 4.7 mm (0.185 ) Brush 1) 2) 3) 4) 5) Layers: 1) Exterior Strap 2) Skin Panels 3) Finger Doublers 4) Longeron 5) Doublers Probe Lift-Off from.063 Strap DC10 Fuselage Skin Crown Splice Graphic Courtesy of QinetiQ Ltd.

12 Lift-Off Compensation Lift-Off Lift-Off Removed Without L/O Compensation With L/O Compensation DC10 Fuselage Skin Crown Splice DC10 Specimen Courtesy Sandia National Labs, AANC

13 Edge Subtraction EDM NOTCHES W/O Edge Subtraction defects under skin splice are difficult to see With Edge Subtraction the skin splice effect is removed and defects can be seen

14 Time-Slice Examples Time-Slices Later in Time Represent Lower Frequencies

15 Defect Depth Measurement Time-To To-Peak 0.31 ms 0.41 ms Measuring the Time to the Peak of a balanced transient can be used to produce simple time-of-flight images, which can be related to depth in the structure.

16 KC135 Case Study Sample Image Courtesy QinetiQ Ltd. Copyright QinetiQ Ltd, 2004

17 Total Thickness Measurement Images structural variations Image Courtesy QinetiQ Ltd. Copyright QinetiQ Ltd, 2004 Metal loss measurement is accomplished using an method that calculates percentage change in total thickness relative to the balance point.

18 Edge Subtraction Image Courtesy QinetiQ Ltd. Copyright QinetiQ Ltd, 2004 Removes edge effects

19 Original TRECSCAN System TRECSCAN was originally developed as a Dynamic Link Library (DLL) plug-in for the ANDSCAN software suite. Using the manual ANDSCAN R-Theta scanner it was capable of scanning relatively small areas of structure. TRECSCAN DLL ANDSCAN Software TRECSCAN Interface Box Probe: Hall Sensor Manual Scanner

20 System Integration Objectives Provide large area transient eddy current C-scan data collection capabilities for the production environment Integrate TRECSCAN into the Boeing MAUS IV Automated C-scan system Couple TRECSCAN with the SAIC Ultra Image IV Automated C-scan system

21 TRECSCAN +MAUS INTEGRATION TRECSCAN DLL MAUS SOFTWARE MAUS TRECSCAN BOARD Probe: Hall Sensor Using Familiar MAUS Operator Interface

22 TRECSCAN +MAUS Integration Approach Boeing built TRECSCAN interface board fits into MAUS chassis QinetiQ built TRECSCAN board nests onto MAUS interface board QinetiQ built TRECSCAN auto-sensing PSU fits into MAUS chassis QinetiQ authored TRECSCAN/MAUS DLL MAUS Software calls the TRECSCAN DLL Operator interface looks like MAUS TRECSCAN DLL revisions will not require MAUS software changes

23 TRECSCAN /MAUS Configuration and Options Setup Screens

24 TRECSCAN /MAUS ImagIn Display Time-slice 1 tab Time-slice 3 tab Time-slices are displayed as separate tabs and can be displayed according to the users preference

25 TRECSCAN +MAUS C-scan Data Time-slice 2 Time-slice 6 Material loss in top sheet Four changes in thickness Splice in plate beneath test standards

26 TRECSCAN +Ultra Image IV Integration TRECSCAN DLL ANDSCAN 2000 Software Ultra Image Scanning System TRECSCAN Interface Box Using ANDSCAN Operator Interface Probe: Hall Sensor

27 TRECSCAN /Ultra Image IV Integration Approach Use TRECSCAN/ANDSCAN Software Use TRECSCAN/ANDSCAN Interface Instead of Ultra Image Dos Based Interface (Windows 98) SAIC Authored Windows Based Motion Control Interface Library QinetiQ Authored ANDSCAN Motion Control DLL Use External TRECSCAN Instrument/Interface Box QinetiQ Built Optical Encoder Signal Conditioner SAIC Built Optical Isolation Unit

28 Original Ultra Image IV Hardware Configuration

29 Ultra Image IV/TRECSCAN Hardware Configuration

30 TRECSCAN /Ultra Image IV Setup Screen Ultra Image IV uses the original TRECSCAN operator interface

31 ANDSCAN /Ultra Image Motion Control Wizard Screen

32 ANDSCAN /Ultra Image Motion Control Joy Stick Display

33 TRECSCAN /Ultra Image Scan Display

34 Current and Future Plans Work on a thick multi-layer wing structure inspection problem on the B-52 Conduct additional experiments to assess the range of capabilities of the TRECSCAN transient eddy current system Develop aircraft specific inspection procedures to the detect and characterize cracks and corrosion in aluminum aircraft skin/structure, giving special consideration to: Back side of the first layer Top side of the second layer. Back side of the second layer and deeper

35 Conclusions TRECSCAN has several unique capabilities offering great potential, and the capability to be applied to many difficult inspection requirements. Integrating TRECSCAN into the USAF Inventory Automated C-scan Systems Brings Transient Eddy Current to the Production Floor. TRECSCAN will be one more tool in the NDI/NDE Thank TOOLBOX You for Your Time! This is just the Beginning

36 Project Team Members NDT Solutions, Inc. (NDTS) QinetiQ Ltd. SAIC Ultra Image International Sandia National Laboratories FAA AANC The Boeing Company U. S. Air Force-AFRL/MLLP and ASC/AAA Universal Technology Corporation (UTC)

37 Thank you! Questions?

38 References 1. D. J. Harrison, Eddy-current inspection using Hall sensors and transient excitation, Defence Research Agency Technical Report DRA/SMC/TR941008, DRA Farnborough, UK, (1994). 2. D. J. Harrison, in Nondestructive Testing of Materials, Studies in Applied Electromagnetics and Mechanics, Vol 8, eds. R. Collins, W. D. Dover, J.R. Bowler and K. Miya, (IOS Press, Amsterdam, 1995), pp S.K. Burke, G.R. Hugo, and D.J. Harrison, in Review of Progress in QNDE, Vol 17A, eds. D. O. Thompson and D. E. Chimenti, (Plenum, New York, 1998), pp G. R. Hugo and D. J. Harrison, in Review of Progress in QNDE, Vol 18B, eds. D. O. Thompson and D. E. Chimenti, (Kluwer Academic/Plenum Publishers, 1999), pp R A Smith and G R Hugo, "Transient eddy-current NDE for aging aircraft - Capabilities and limitations", Proc 4th Joint DoD/FAA/NASA Conf on Aging Aircraft, St Louis, May R A Smith and G R Hugo, "Transient eddy-current NDE for ageing aircraft - Capabilities and limitations", Insight - The Journal of The British Institute of NDT, Vol 43, No 1, pp 14-20, D J Harrison, "The characterisation of cylindrical eddy-current probes in terms of their spatial frequency spectra". IEE Proceedings; Science, Measurement and Technology (SMT), Special Issue on Non-Destructive Testing and Evaluation, Vol 148, No 4, July R A Smith and G R Hugo, "Deep corrosion and crack detection in aging aircraft using transient eddycurrent NDE", Proc 5th Joint NASA/FAA/DoD Conf on Aging Aircraft, Orlando, Sept R A Smith, Dave Edgar and Jesse Skramstad, Advances in Transient Eddy-current Imaging for Aerospace Applications WCNDT Conf. Aug 2004 ANDSCAN and TRECSCAN are a Registered Trademarks of QinetiQ Ltd, in the United Kingdom MAUS and ImagIn are Registered Trademarks of The Boeing Company