Use of Waves (3)

Question 1

Use of Longitudinal Waves

Answer 1

Can enter at:
90° (Normal Incidence)
or
slight angle (Oblique Incidence)

Question 2

What are Normal Incidence Waves used for?

Answer 2

Detecting:

• Material Thickness
• Discontinuities parallel to the surface
• Determine lack of bonding between two materials

Question 3

What are Oblique Incidence Waves used for?

Answer 3

Detecting discontinuities that aren’t parallel to the surface, need to produce a shear and longitudinal wave (mode conversion)

required a specially cut wedge, cut below the first critical angle.

Question 4

Use of Shear Waves

Answer 4

Detect discontinuities that are angled to the surface (weld inspections)

Question 5

Use of Surface Waves

Answer 5

Detect surface breaking discontinuities

• surface must be smooth, clean, free of scratches
• must be an air boundary at the surface

Question 6

Define the term “Finger Dampening”

Answer 6

Method of verifying that a surface wave is present but placing a finger in its path this should cause the signal to disappear.