Non Destructive Testing:Finding Defects in Metal Objects

Design Team 4:•Chad Church

•Ron Fox

•John Vogel

•Geoff Brigham

•Matt Hamm

Agenda

• The Need For Non-Destructive Testing• Methods of NDT

– Eddy Currents

– Acoustic

– Ultrasonic Testing

• Summary

Non-Destructive Testing

• Industrial Application– Crack Detection

– Wall Thinning

– Porosity

– Thickness of Material

• Medical Application– Ultrasound

– X-Ray

http://zone.ni.com/cms/images/devzone/tut/a/7e46be30706.gif

“Test object, material or system without impairing its future usefulness”

Benefits of NDT

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

Methods of NDT

• Visual Testing

• Penetrant Testing

• Magnetic Particle Testing

• Infrared/Thermal Testing

• Eddy Current Testing

• Acoustic Emission Testing

• Ultrasonic Testing

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!

Method: Eddy Currents

• Detect:– Conductivity

– Magnetic Permeability

– Distance

– Presence of a flaw

• Depth of penetration• “Skin effect”• Exponential drop-off

Method: Eddy Currents

• Limitations

• Aluminum parts• Iron parts

Method: Acoustic Testing

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

Method: Acoustic Testing

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

doi:10.1006/jaer.2000.0542    

Method: Acoustic Testing

Method: Acoustic Testing

Method: Acoustic Testing

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

Method: Ultrasonic Testing

• Sound Waves• 100 KHz to 50 MHz for NDT• Short Wavelength

– Reflections Off Small Defects

• Requires Elastic Medium

What is Ultrasound?

http://www.olympus-ims.com/data/File/panametrics/UT-technotes.en.pdf

Method: Ultrasonic Testing

• Components of an Ultrasonic Flaw Detector– Power Supply

– Timer

– Pulser/Amplifier

– Ultrasonic Transducer

– Receiver

– Computer Display

Method: Ultrasonic Testing

• Electrical Energy Mechanical Energy• Piezoelectric Effect• Alternating Voltage Applied To Crystal• Crystal Expands and Contracts

– Creates High Frequency Alternating Charge on Crystal

Ultrasonic Transducer

Method: Ultrasonic Testing

• High Frequency/Short Wavelength– Minimal Propagation in Air Medium

• Types of Couplants– Oil– Glycerine– Water

• Another Option– Direct Contact Transducer

Couplants

Method: Ultrasonic Testing

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

Advantages of Ultrasonic Testing

Method: Ultrasonic Testing

• Sensitivity• Resolution• Noise Discrimination

Limitations of Ultrasound

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?v=IE6wk1Z-bLc&NR=1)

Questions?