Ultrasonic level 1 Flashcards
The cable that connects the ultrasonic instrument to the search unit is specially designed so that one conductor is centred inside another. The technical name for such a cable is?
Coaxial Cable
The process of comparing an instrument or device with a standard is called:
Calibration
A material used between the face of a search unit and the test surface to permit or improve the transmission of ultrasonic vibrations from the search unit to the material being tested is called?
A couplant (Reduce the impedance mismatch)
Ultrasonic testing of material where the search unit is in direct contact with the material being tested may be?
All of these: Straight beam testing, surface wave testing and angle beam testing.
The indication on the cathode ray tube (CRT) which represents the far boundary of the material being tested is called?
Back wall echo or aka The back surface reflection
When an ultrasonic beam passes through the interface between two dissimilar materials at an angle, a new angle of sound travel takes place in the second material due to?
refraction
The amount of beam divergence from a crystal is primarily dependent on the?
Frequency and crystal size
Which of the following materials of the same alloy is most likely to produce the greatest amount of sound attenuation over a given distance.
A course-grained casting (Grey casting)
A test method employed two separate search units on opposite surfaces of material being tested is called?
Through-transmission testing.
The boundary between two different materials which are in contact with each other is called?
An interface
When the motion of the particles of a medium is parallel to the direction of propagation, the wave being transmitted is called a.
Longitudinal wave
“25 million cycles per second” can also be stated as?
25MHz
A term used in ultrasonics to express the rate at which sound waves pass through various substances is?
Velocity
In an A-scan presentation, the horizontal base line represents?
The Elapsed time or distance
In ultrasonic testing. a liquid coupling medium between the crystal surface and the part surface is necessary because?
An air interface between the crystal surface and the part surface would completely reflect the ultrasonic vibrations.
Sound waves of a frequency beyond the hearing rang of the human ear are referred to as ultrasonic waves or vibrations, and the term embraces all vibrational waves of frequency greater then approximately?
20 000Hz
The velocity of sound waves is primarily dependant on?
the material in which the sound is being transmitted and the mode of vibration.
The primary purpose of reference blocks is to?
Obtain a common reproducible signal.
The angle of incidence is:
Equal to the angle of reflection.
The depth of a discontinuity cannot be determined when using the?
Through-transmission testing method. (2 probe method)
The interference field near the face of a transducer is often referred to as the?
Fresnel Zone (NZP)
The product of the acoustic velocity of sound in a material and the density of the material is the factor that determines the amount of reflection or transmission of ultrasonic energy when it reaches an interface. This term is called?
Acoustic impedance (Z=PxV)
The formula used to calculate the angle of reflection with a material is called?
Snells law
In a material with a given velocity, when frequency is increased the wavelength will?
Decrease
Which is a plot of signal amplitude versus time?
an A-Scan display
As the grain size increases, its principal effect is ultrasonic testing is on the?
Attenuation
In straight beam pulse echo testing, a discontinuity with a rough reflecting surface perpendicular to the incident wave will have what effect on the detected signal in comparison to a smooth flat bottom hole of the same size?
Decrease it
Ultrasonic vibrations are commonly used to?
Examine materials for discontinuities, for thickness and for mechanical properties (All of them)
Which of the following has the longest Fresnel Zone. (NZP)
- 13mm diameter 1MHz
- 13mm diameter 2.25 MHz
- 28.5mm diameter 1 MHz
- 38mm diameter 2MHz
Hint: V = diameter squared, divided by 4 x wavelength
- 38mm diameter 2MHz
Remember:
V = diameter squared, divided by 4 x wavelength
In immersion testing, a wetting agent is added to the water to?
Help eliminate the formation of air bubbles
The variable in distance amplitude calibration block construction is the?
Metal distance above the drill hole
In immersion testing, when the sound beam strikes a concave surface, the sound beam tends to?
Converge
Most ferrous and non-ferrous welds may be ultrasonically tested using a frequency range of ?
1 - 2.25 (check this answer)
In selecting a suitable couplant, which of the following characteristics would NOT affect the selection?
- Mode of propagation.
- material surface finish & temp
- operating frequency of the transducer
- chemical properties of the couplant
Mode of propagation desired.
Meaning of: ‘Critical angle’
The incident angle of the ultrasonic beam beyond.
‘Surface Wave’ also known as?
Rayleigh waves
When measuring a ‘Curved Surface’.
you would use Single crystal or twin crystal?
Small diameter probe - twin crystal prob = more surface area
