Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
19 Cards in this Set
- Front
- Back
How can the defect be sized using the time of signals?
|
a = cosθ*(Δt*v/2)
|
|
How can the frequency spectrum of combined signals help to size a defect?
|
PICTURE
a = cosθ*(Δt*v/2) |
|
What can velocity and attenuation of material be used for?
|
Estimating material characteristics such as
- grain size and concentration - porosity content - material anisotropy - residual stress |
|
What can variations in velocity be used for in material characterisation?
|
v prop root(avgElasticModulus/avgDensity)
this could be porosity content, grain characteristics, material mix |
|
What can variations in attenuation be used for in material characterisation?
|
scattering induced attenuation is related to size, shape and volume fraction of simple scatterers
|
|
How would residual stress or anisotropic characteristics be detected?
|
Mechanical working affects velocity. Therefore accurate velocity measurements techniques are required
|
|
What are the most common methods of ultrasound generation?
|
- Piezoelectronic transducers
- Magnetostrictive transducers - EMATs (Electromagnetic Acoustic transducers) - Laser generation - Impact |
|
What are magnetostrictive transducers?
|
Transducers which have material which changes shape due to the influence of a magnetic field
|
|
How does an Electromagnetic Acoustic transducer work?
|
Eddy currents induced by coil on material surfaceinteract with permanent magnet which result in the vibration of specimen surface
|
|
What are the most important features of Electromagentic Acoustic transducers?
|
- The wave generation process is reciprocal
- Non-contact method whic his good for hot-surface inspection |
|
How does laser generation of ultrasonic waves work?
|
Surface is struck by laser pulses which heats the specimen locally and thus expands. Ultrasonic waves created due to expansion and contraction of material
|
|
What is an advantage of laser generation ultrasonic waves?
|
Non-contact
|
|
What are the disadvantages of ultrasonic waves?
|
- Material damage may occur
- Detection is complex |
|
Draw the set-up of a piezoelectronic transducer
|
IMAGE
|
|
Draw the set-up of a shear wave transducer
|
IAMGE
|
|
Draw a B-scan system
|
IMAGE
|
|
draw an A-scan system
|
IMAGE
|
|
draw a shear wave EMAT
|
Image
|
|
Draw a compressional wave EMAT
|
image
|