Basic Principles of Ultrasonic Testing

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basic principles of ultrasonic testing Wave propagation

Longitudinal waves propagate in all kind of materials.
Transverse waves only propagate in solid bodies.
Due to the different type of oscillation, transverse wavestravel at lower speeds.
Sound velocity mainly depends on the density and E-modulus of the material.

Reflection and Transmission


As soon as a sound wave comes to a change in material characteristics ,e.g. the surface of a workpiece, or an internal inclusion, wave propagation will change too:


Reception of ultrasonic waves


A sound wave hitting a piezoelectric crystal, induces crystal vibration which then causes electrical voltages at the crystal surfaces.