Pulse-Echo (2)

Question 1

What is the Pulse-Echo Technique?

Answer 1

• Send electrical pulse to transducer
• transducer convert pulse into mechanical vibration
• transducer receives reflection of mechanical vibration, converts into electrical pulse to be read by UT Instrument.

Question 2

Initial Pulse

Answer 2

Electrical Pulse sent to the transducer

Question 3

Front Surface Echo

Answer 3

Mechanical vibration bouncing off of the front surface of material (remember that some sound enters the material and some bounces off of the surface)
- Normally seen on UT screen very close to the Initial Pulse

Question 4

1st Backwall Echo

Answer 4

When the crystal first vibrates and an electrical signal is sent back to the instrument.

Question 5

2nd Backwall Echo

Answer 5

Sound that travels through the thickness of the part material and reflected back to the transducer is called the 1st Backwall Echo
- Range set on the instrument will determine the # of Backwall reflections.

Question 6

Pulse-Echo using a Straight-Beam Contact Transducer with a Delay Line

Answer 6

The sound will travel a longer distance through the delay line, taking more time for the crystal to stop ringing before the echo from the front surface arrives.
- this will separate the initial pulse from the front pulse instead of them being squished together.

Question 7

How are discontinuities shown on a UT screen?

Answer 7

Appear in a position relative to the material thickness, and the height of the signal shows how much sound returned from hitting the defect (how much material is between the surface and where the discontinuity starts)