7: Interpreting Results Flashcards
3 problems that occur due to large grain structure, porosity or precipitates.
- Scattering
- Attenuation
- Noise on screen
What are the solutions for scattering, attenuation and noisy screen?
- Lower probe frequency
- Inspect 90 degree to grain structure
- Reduce beam spread (increase probe diameter)
- Test from opposite/adjacent surfaces
What problems could occur with a rough surface? (3)
- Mode conversion/refraction
- Attenuation
- Widening of the IP
What are 3 solutions to rough surface problems (mode conversion/refraction, attenuation and widening of IP)? (3)
- Smooth the surface
- Use thicker couplant
- Lower probe frequency
What are 2 problems that could occur when testing a hot surface?
- Damage to transducer
2. Cannot obtain results
What are 2 solutions to testing on a hot surface?
- Use a hot temp probe
2. Use a high temp couplant
What problem could occur with testing on a vertical or overhead surface? And the solution?
Problem: Couplant runs down
Solution: use thicker couplant
What 2 problems could occur with testing a specimen with unparalleled surfaces?
- Mode conversion at back surface
2. Loss of back surface reflection
What is a solution to testing a specimen with unparalleled surfaces?
Obtain measurements or blueprint of the part
What are 2 problems you could encounter with testing a long thin specimen?
Mode conversion and attenuation.
When testing a long thin specimen, what are two solution to the mode conversion and attenuation you will encounter?
- Reduce beam spread (increase probe diameter or frequency)
2. Inspect from both ends
What are 3 problems you may encounter when testing on a small concave/convex surface?
- Mode conversion and refraction
- Attenuation
- Back wall reflection not clear
What is a solution to the problems you will encounter when testing small concave/convex surfaces?
Use a cylindrical lens that matches contour of the part.
What are two problems you may encounter when testing thin material?
- Defects in the dead zone
2. Hard to read indications
What are 3 solutions to the problems you will encounter when inspecting thin material (defects in dead zone and hard to read indications)?
- Use a delay line or dual probe
- Immersion testing
- Through-transmission technique
What problem will you encounter when inspecting large surfaces?
Time consuming
How can you speed up inspection when testing a large surface?
Use a larger diameter or paintbrush transducer
What problem will you encounter when testing for a discontinuity at an angle?
Small/no signal from discontinuity
How do you fix the problems that will be involved with finding a discontinuity at an angle?
Use an angle-beam transducer
What problem might you encounter when testing a rough discontinuity? And what is the solution?
Problem: reduced signal due to scatter
Solution: increase gain
What problem might you encounter with a discontinuity in the dead zone?
Can’t detect in
What are 6 solutions when trying to detect a discontinuity in the dead zone?
- Increase probe frequency
- Use broad bandwidth probe
- Reduce pulse length
- Use a dual/delay-line transducer
- Test with immersion/through-transmission
- Test from opposite side
Increasing the diameter of probe will do what to penetration power?
Increase it
Increasing diameter of probe will do what to the beam spread?
Decrease it