Non Destructive Testing: Finding Defects in Metal Objects

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Non Destructive TestingFinding Defects in Metal
Objects

• Design Team 4
• Chad Church
• Ron Fox
• John Vogel
• Geoff Brigham
• Matt Hamm

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Agenda

• The Need For Non-Destructive Testing
• Methods of NDT
• Eddy Currents
• Acoustic
• Ultrasonic Testing
• Summary

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Non-Destructive Testing
Test object, material or system without
impairing its future usefulness

• Industrial Application
• Crack Detection
• Wall Thinning
• Porosity
• Thickness of Material
• Medical Application
• Ultrasound
• X-Ray

http//zone.ni.com/cms/images/devzone/tut/a/7e46be
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Benefits of NDT

• Ensure Product Integrity
• To Avoid Failures
• Better Product Design
• Lower Manufacturing Costs
• Maintain Uniform Quality Level

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Methods of NDT

• Visual Testing
• Penetrant Testing
• Magnetic Particle Testing
• Infrared/Thermal Testing
• Eddy Current Testing
• Acoustic Emission Testing
• Ultrasonic Testing

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Method Eddy Currents

• Eddy current probe is a coil of wire
• Induces a magnetic field
• Induces a current in the part
• Induces a magnetic field
• Induces a current in the probe
• Measure the Current
• VICTORY!

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Method Eddy Currents

• Detect
• Conductivity
• Magnetic Permeability
• Distance
• Presence of a flaw
• Depth of penetration
• Skin effect
• Exponential drop-off

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Method Eddy Currents

• Limitations
• Aluminum parts
• Iron parts

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Method Acoustic Testing

• Inspiration Hit it with a hammer, listen
• Resonance frequency
• Harmonic frequencies
• Fourier transform

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Method Acoustic Testing

• Mechanical impact on different locations
• Microphone reception
• Fourier Transform
• Correlation of multiple impact resonations

doi10.1006/jaer.2000.0542    
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Method Acoustic Testing
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Method Acoustic Testing
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Method Acoustic Testing

• Variety of material and composition
• Environmental deterioration
• Damping
• Access to many points

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Method Ultrasonic Testing
What is Ultrasound?

• Sound Waves
• 100 KHz to 50 MHz for NDT
• Short Wavelength
• Reflections Off Small Defects
• Requires Elastic Medium

http//www.olympus-ims.com/data/File/panametrics/U
T-technotes.en.pdf
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Method Ultrasonic Testing

• Components of an Ultrasonic Flaw Detector
• Power Supply
• Timer
• Pulser/Amplifier
• Ultrasonic Transducer
• Receiver
• Computer Display

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Method Ultrasonic Testing
Ultrasonic Transducer

• Electrical Energy Mechanical Energy
• Piezoelectric Effect
• Alternating Voltage Applied To Crystal
• Crystal Expands and Contracts
• Creates High Frequency Alternating Charge on
  Crystal

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Method Ultrasonic Testing
Couplants

• High Frequency/Short Wavelength
• Minimal Propagation in Air Medium
• Types of Couplants
• Oil
• Glycerine
• Water
• Another Option
• Direct Contact Transducer

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Method Ultrasonic Testing
Advantages of Ultrasonic Testing

• Fast Response
• Accuracy
• High Sensitivity
• Flexibility
• Penetrating Power

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Method Ultrasonic Testing
Limitations of Ultrasound

• Sensitivity
• Resolution
• Noise Discrimination

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Summary

• Necessary to use a Non Destructive Testing
• Eddy Currents
• Abilities
• Problems
• Acoustic
• Abilities
• Problems
• Ultrasound
• Abilities
• Problems
• Team Designed Method

(http//www.youtube.com/watch?vIE6wk1Z-bLcNR1)
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Questions?