Wave Propagation

Question 1

In solids, sound waves can propagate in four principle modes, what are they?

Answer 1

Sound can propagate as longitudinal waves, shear waves, surface waves, and in thin materials as plate waves

Question 2

Which two wave modes are most commonly used in ultrasonic testing?

Answer 2

Shear Wave and Longitudinal

Question 3

Explain what a longitudinal wave is?

Answer 3

In longitudinal waves, the oscillations occur in the longitudinal direction or the direction of wave propagation. Since compressional and dilatational forces are active in these waves, they are also called pressure or compressional waves.

Question 4

Explain what a shear wave is?

Answer 4

In the transverse or shear wave, the particles oscillate at a right angle or transverse to the direction of propagation. Shear waves require an acoustically solid material for effective propagation, and therefore, are not effectively propagated in materials such as liquids or gasses