Local Nondestructive Evaluation and Materials Characterization

1
Local Nondestructive Evaluation and Materials
Characterization

• Glenn A. Washer, Ph.D., P.E.
• University of Missouri Columbia
• washerg_at_missouri.edu

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Agenda

• Introduction in NDE
• NDE timelines
• NDE for defect detection
• Materials Characterization
• Conclude

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Nondestructive Evaluation

• Technologies to determine the condition of a
  material without altering that condition

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What are NDE Methods?

• NDE methods use waves to transmit data on
  material condition
• Acoustic 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 flight
• Example visual inspection
• Reflection of light

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Why NDE?

• Safety detect deterioration at sub-critical
  levels
• Fatigue cracks in steel bridges
• Maintenance detect deterioration during
  embryonic stages to
• Identify repair needs
• Reduce the cost of repairs
• Management
• Provide quantitative knowledge
• on inventory condition
• Focus funding on most
• critical needs
• Quality Control
• Materials characterization

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Classifying NDE Technologies

• Local defect detection
• Single point binary detection (threshold)
  analysis
• UT, ET, MT, etc
• Full-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 Techniques
• Health Monitoring
• Stress, strain, dynamic characteristics
• Corrosion, distributed local NDE technologies
  within a system
• Materials Characterization
• Quality control
• Gross Materials Degradation
• UT pulse velocity in concrete

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Timelines and NDE

• Most 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 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 damage

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Timelines and NDE

• Pre-construction
• Material characterization, defect detection
• Weld flaws, voids in pre-cast concrete
• Characterizing earth properties
• Construction
• Quality control, installation stresses
• Ex. Anchor bolt stresses, erection stresses
• Post-construction
• GPR for pavement thickness, rebar depth etc.
• Service Life
• Detect deterioration and defect growth
• Deconstruction
• Quantify material conditions/properties following
  service life
• Corrosion rates, chloride intrusion etc.

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Example

• Acoustic detection of subsurface features

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September 2000

• Imaging of acoustic backscatter (density changes)
• Fixed point in time
• Detection and analysis single fetus

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November, 2000
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Jack and Beau
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Pin Inspection
Ref FHWA NDE Center
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Bridge Pin EvaluationC-Scan Image
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Phased Array Ultrasonics
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Pin Radiography
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Computed Tomography
099
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Acoustic Wave Spectrum
A/E
Audible
Impact - echo
Ultrasonic
Structural vibrations
1
101
102
103
104
105
106
107
KHz
Hz
MHz
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MHz
KHz
GHz
MHz
THz
PHz
radar
IR
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Materials Characterization

• Waves 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 elasticity
• Scale
• Magnitude
• NDE technologies can measure physical properties
  when other variables can be controlled
• Quality control, production control, and
  global/localized materials degradation

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Equation of Motion for a Anisotropic Linear -
Elastic Solid
Orthortropic Case

• vij wave velocity
• density
• m,l Lamé Constants

• u Poissone ratio
• u Displacement

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RPC Structure
3D reconstruction (steel fibers)
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UT vs. Static ModulusBy Curing Method
Correlation coef. 0.94
9000
8500
Steam cured
Delayed Steam
8000
Tempered Steam
Air Cured
STATIC MOD. (ksi)
7500
7000
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6500
6000
6000
6500
7000
7500
8000
8500
9000
UT Modulus (ksi)
Ref. Washer, Fuchs, Graybeal Rezai, QNDE 2003
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Acoustoelastic Equation of Motion
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Concept
Transmitter
P/S Beam
Receiver pair
Strand
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Strands
Ref. Washer, Green Pond, RNDE 2001
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Future Opportunities
Managing the aging infrastructure into the future
will require the development of increasing
sophisticated condition assessment tools

• NDE Technologies
• Detect defects and material degradation
• Physical properties of engineering materials
• Variability and scale of civil structures
  presents a significant challenge
• Local NDE techniques can be distributed as part
  of health monitoring systems
• Development of systematic approaches and sensor
  technologies is required

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Acknowledgements

• FHWA NDE Center

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Thank you Questions?