1. Local Nondestructive Evaluation and Materials Characterization Glenn A. Washer, Ph.D., P.E. University of Missouri – Columbia washerg@missouri.edu

2. Agenda Introduction in NDEIntroduction in NDE NDE timelinesNDE timelines NDE for defect detectionNDE for defect detection Materials CharacterizationMaterials Characterization ConcludeConclude

3. Nondestructive Evaluation Technologies to determine the condition of a material without altering that conditionTechnologies to determine the condition of a material without altering that condition

4. What are NDE Methods? NDE methods use waves to transmit data on material conditionNDE methods use waves to transmit data on material condition Acoustic and electromagnetic waves carry the legacy of their environmentAcoustic and electromagnetic waves carry the legacy of their environment NDE methods measure common wave properties to infer the condition of the material – frequency, amplitude, time of flightNDE methods measure common wave properties to infer the condition of the material – frequency, amplitude, time of flight –Example: visual inspection –Reflection of light

5. Why NDE? Safety – detect deterioration at sub-critical levelsSafety – detect deterioration at sub-critical levels –Fatigue cracks in steel bridges Maintenance – detect deterioration during embryonic stages to:Maintenance – detect deterioration during embryonic stages to: – Identify repair needs –Reduce the cost of repairs ManagementManagement –Provide quantitative knowledge on inventory condition –Focus funding on most critical needs Quality ControlQuality Control –Materials characterization

6. Classifying NDE Technologies Local defect detectionLocal defect detection –Single point binary detection (threshold) + analysis –UT, ET, MT, etc Full-Field defect detection and imagingFull-Field defect detection and imaging –Spatial representation of common wave properties (ex. Amp. ) –Binary detection (threshold) + quantitative spatial measurements + analysis –Infrared thermography, imaging (dt), interferometric optical methods Global TechniquesGlobal Techniques –Health Monitoring Stress, strain, dynamic characteristicsStress, strain, dynamic characteristics Corrosion, distributed local NDE technologies within a system Corrosion, distributed local NDE technologies within a system Materials CharacterizationMaterials Characterization –Quality control –Gross Materials Degradation UT pulse velocity in concreteUT pulse velocity in concrete

7. Timelines and NDE Most traditional NDE technologies are historicalMost traditional NDE technologies are historical –Record events that have previously occurred –Defects are detected once they have grown to detectable levels –Inspection intervals can be optimized for these techniques such that known defect growth rates combined with known POD rates form a reliable and safe system There are a few exceptionsThere are a few exceptions –Acoustic Emission systems –“Real time” is a benefit and a deficiency Cannot measure damage that already exists, and generally is not intended to detect manifestations of that damageCannot measure damage that already exists, and generally is not intended to detect manifestations of that damage

8. Timelines and NDE Pre-constructionPre-construction –Material characterization, defect detection Weld flaws, voids in pre-cast concreteWeld flaws, voids in pre-cast concrete Characterizing earth propertiesCharacterizing earth properties ConstructionConstruction –Quality control, installation stresses Ex. Anchor bolt stresses, erection stressesEx. Anchor bolt stresses, erection stresses Post-constructionPost-construction –GPR for pavement thickness, rebar depth etc. Service LifeService Life –Detect deterioration and defect growth DeconstructionDeconstruction –Quantify material conditions/properties following service life Corrosion rates, chloride intrusion etc.Corrosion rates, chloride intrusion etc.

9. Example Acoustic detection of subsurface featuresAcoustic detection of subsurface features

10. September 2000 Imaging of acoustic backscatter (density changes)Imaging of acoustic backscatter (density changes) Fixed point in timeFixed point in time Detection and analysis – single fetusDetection and analysis – single fetus

11. November, 2000

12. Jack and Beau

13. Pin Inspection Ref: FHWA NDE Center

14. Bridge Pin Evaluation C-Scan Image

15. Phased Array Ultrasonics

16. Pin Radiography

17. Computed Tomography 099

18. Acoustic Wave Spectrum 110 1 10 2 10 3 10 4 10 5 10 6 10 7 Structural vibrations KHzHzMHz Audible Impact - echo Ultrasonic A/E

19. radarIR MHzKHzGHzMHzTHzPHz

20. Materials Characterization Waves carry the legacy of the environment in which they propagateWaves carry the legacy of the environment in which they propagate –Electromagnetic waves and acoustic waves Many physical properties are linear over certain ranges, for example steel modulus of elasticityMany physical properties are linear over certain ranges, for example steel modulus of elasticity –Scale –Magnitude NDE technologies can measure physical properties when other variables can be controlledNDE technologies can measure physical properties when other variables can be controlled –Quality control, production control, and global/localized materials degradation

21. Equation of Motion for a Anisotropic Linear - Elastic Solid Orthortropic Case Isotropic Case v ij = wave velocity  = density  = Lamé Constants  = Poisson’e ratio u = Displacement

22. RPC Structure 3D reconstruction (steel fibers)

23. UT vs. Static Modulus By Curing Method 6000 6500 7000 7500 8000 8500 9000 6000650070007500800085009000 UT Modulus (ksi) STATIC MOD. (ksi) Steam cured Delayed Steam Tempered Steam Air Cured 1:1 Correlation coef. 0.94 Ref. Washer, Fuchs, Graybeal & Rezai, QNDE 2003

24. Acoustoelastic Equation of Motion  

25. Concept Transmitter Receiver pair P/S Beam Strand

26. Strands Ref. Washer, Green & Pond, RNDE 2001

27. Future Opportunities NDE TechnologiesNDE Technologies –Detect defects and material degradation –Physical properties of engineering materials Variability and scale of civil structures presents a significant challengeVariability and scale of civil structures presents a significant challenge Local NDE techniques can be distributed as part of health monitoring systemsLocal NDE techniques can be distributed as part of health monitoring systems –Development of systematic approaches and sensor technologies is required Managing the aging infrastructure into the future will require the development of increasing sophisticated condition assessment tools

28. Acknowledgements FHWA NDE CenterFHWA NDE Center

29. Thank you – Questions?