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23 Cards in this Set
- Front
- Back
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Longitudinal Wave (L)
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Particle motion is parrallel to the surface of the part
Only wave mode that will travel in solids,liquids and gases Fastes mode of vibration |
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Shear Wave (L)
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Particle motition is perpendicular to the direction the wave travels. Only in solids
Travel at approximately 1/2 the L wave velocity Smaller wavelength of than the L wave at the sme frequency |
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Surface Wave
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Particle motion is ellipical
Travels only in solids Approximately 45% of velocity of L waves Penetrates to a depth of one wavelength Used in contact testing Requires a clean surface |
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Mode Conversion
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Changing of sound wave from one mode to another
Caused by the reflection or refraction of sound at an interface when the incident angle is greater than zero degress |
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Reflection
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The sound bounces off the part's walls (interface) staying in the same material
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Refraction
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The bending of the sound wave as it crosses the interface at an incident angle greater than zero
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Accoustic Impedance (z)
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The resistance of the material to propagation of sound
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Accoustic Impedance formula
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material velocity x density Z=CD
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Amount Of Sound Reflection
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The amount of reflection at an interface depends upon the angle of incidence and accoustic impedance mismatch
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Velocity
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The rate a which sound travels through a material
Depends on the material density and elastisity and the mode of vibration. Note- Velocity is constant for a given mode and material |
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Cycle
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A complete repetition of particle motion
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Beam Spread
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Degree of spread is determined by the frequency and diameter of the crystal.
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Beam Spread- Higher Frequency
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Less Beam Spread
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Beam Spread-Larger Diameter
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Less beam spread
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The more narrow the beam spread
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The Higher the intensity
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Dead Zone
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Transmission time. The crystal cannot recieve while transmitting.
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Near Zone
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Zone where the sound wave has not achieved a uniform pattern. Constructive and destructive interefence occuring here.
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Peak Point
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The end of the near field
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Far Zone
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Zone where the sound has achieved a uniform wave pattern. Best Flaw evaluation
Attenuation and beam spread start to be noticed |
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Attenuation
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The Loss of sound intensity as the wase travels through the material
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Pulse Repetition Rate
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The number of pulses produced per second
Based on the thickness of this material Thicker material = less PRR Thinner Material = More PRR |
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Decibels
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A measure of Sound for the stating the relationships between sound amplitudes.
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Penetration
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The ability to overcome attenuation
To improve penentration increase the pulse length The lower the transducer frequency the longer the wavelength. Increase initial pulse voltage, longer crystal ringing Decrease transducer damping, longer crystal ringing |
