Glossary of ULTRASONIC TESTING
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- ULTRASONIC IS THE NAVY GIVEN TO?
- SOUND FREQ ABOVE 20,000 HZ THE RANGE A HUMAN EAR CAN NOT HEAR.
- WHAT ARE THE MOST COMMONLY USED FREQ IN U/T?
- 2.25, 5, 10 MHZ
- MHZ IS RESPRESNTED AS?
- 1 MILLION CYLCES PER SECOND.
- HOW IS TRANSMISSION OF U/T CHARACTERIZED?
- BY PERIODIC VIBRATIONS REPRESENTED BY WAVE MOTION.
- THE DISTANCE AN ULTRASONIC WAVE TRAVELS PER UNIT TIME IS?
- WAVELENGTH IS EQUAL TO TRAVEL DISTANCE FOR?
- ONE CYCLE
- THE TOTAL NUMBER OF CYCLES PASSING A GIVEN POINT IN 1 SEC?
- THE TOTAL DISTANCE TRAVELED PER UNIT TIME OR ACOUSTIC VELOCITY IS EQUAL TO?
- WAVELENGHTH TIMES FREQ
- HOW ARE VIBRATIONS GENERATED?
- BY APPLING HIGH FREQ ELECTRICAL PULSES TO A TRANSDUCER ELEMENT CONTAINED IN A SEARCH UNIT.
- WHAT IS PIEZOELECTRIC?
- THE ABILITY OF A MATERIAL TO CONVERT ELECTRICAL ENERGT INTO MECHANICAL ENERGY AND VICE VERSA.
- WHAT TRANSFORMS ELECTRICAL ENERGY INTO MECHANICAL ULTRASONIC ENERGY AND RECEIVE AND TRANSFORM U/T ENERGY BACK INTO ELECTRICAL ENERGY
- TRANSDUCER ELEMENTS
- HOW IS ULTRASONIC ENERGY TRANSMITTED FROM A SEARCH UNIT TO A TEST PART?
- THRU COUPLING MEDIUM TO PREVENT AIR INTERFACE BETWEEN THEM.
- IN WHAT TECHNIQUE ARE SHORT BURSTS OF ULTRASONIC ENERY ARE INTRODUCED INTO A PART AT REGULAR INTERVALS OF TIME?
- PULSE ECHO
- WHAT IS THRU TRANSMISSION?
- WHEN A TRANSMITTING SEARCH UNIT PLACED ON ONE SRUFACE AND RECIVING UNIT PLACED ON THE OPPOSITE SURFACE.
- HOW ARE DISCONTINUITIES DISCOVERD WITH THE THRU TRANSMISSION TECH?
- THEY BLOC PASSAGE OF SOUND.
- WHAT METHOD IS THE SEARCH UNIT PLACED DIRECTLY ON THE SURFACE?
- HOW MANY MODES OF PROPAGATION ARE THERE?
- LONGITUDINAL(COMPRESSED), SHEAR(TRANSVERSE), SURFACE( RAYLEIGH), AND LAMB(PLATES)WAVES.
- What are characterized by particle movement parallel to direction of sound beam?
- Longitudinal or compression waves
- compression waves can propagate throught what materials?
- solids, liquids or gases
- characterized by particle movement perpendicular to the direction of the sound beam?
- shear or transverse waves
- What travels approximately 1/2 the speed of logitudinal waves?
- what consists of a transducer element mounted on a plastic wedge so waves ener the testpart at an angle?
- The most sensitive wave of the three types?
- a special type of shear wave in which the motion of the particles is confined to a thin layer of a solid?
- Surface wave or rayleigh.
- Surface waves can refelect around?
- Surface waves can detect defects how fare below the surface?
- 1/2 wave length below surface
- propagtion occurs when waves travel along a test part thinner than 4 wave lengths?
- Lamb(plate) waves
- sound beams have properties similar to?
- Light beams
- the angle at which sound is introduced into a part?
- angle of incidence
- the angle of incidence is equal to?
- Angle of reflection
- Sound reflects off an interface at the same angle at which it?
- travels through the material
- The change in direction of ultra sonic beam as it passes obliquely throug the interface between two materials with different acoustic velocities.
- snells law applys to what?
- incident and refracted angles
- The characteristic of surfaces to change the mode of propagation of acoustic energy from one mode to another?
- mode conversion
- the incident angle of sound beam beyond which a specific refracted mode of vibration no longer exists?
- critical angle
- the critical angle at which longitudinal and shear waves no longer exist?
- above the second critical angle
- Sound beams are not straight sided projections they?
- spread out and vary in intensity
- in contact scanning there is an area beneath search units which cannot be inpected due to large initial pulse?
- Dead zone
- What is inherent to all UT equipment?
- Dead zone
- the shorter the post length the?
- Shallower the dead zone
- Area directly under a search unit to where the beam begins to spread?
- Near field Fresnel zone
- Near fields are not recommended for inspection due to?
- amplitude variations
- What is the far field and what else is it know as?
- The zone beyond the near field. Fraunhofer zone
- The intensity of the far field drops of exponentially as what?
- distance from the face of the transducer increases.
- What spreads in the far field?
- beam spread
- At a given freq the larger the transducer the?
- Less the beam spread and vise versa
- less beam spread means what?
- you have a high freq in the part and vice versa
- Why is beam spread important to calculate?
- ceacuse in certain inspection applications the spreading sound beam can reflect off of walls or edges and casue confusing signals.
- greater sensitivity is aquired by using?
- Higher freq
- Greater penetration is aquired by?
- using lower frequencey
- Defects need to be at least on dimension equal to or greater than what to dectect defects?
- 1/2 the wave length side
- coarse grain structures slatter and absorb what?
- sound energy
- depth of penetration in coarse materials are?
- Surface conditions can cause what?
- insufficant ultasonic energy reaching defects.
Beam divergants or widing of the sound beam
- to minimize the effects of surface conditions the part shall be free of?
- loose heavy or uneven scales machining or grinding particals or other loose foreign matter
- The position of the sides and walls of the part can affect the test what part of variables affecting transmission is this?
- geometry of the part
- A back surface not parallel to the front surface can casue reflections at other than normal angles thus mode conversion in the part this can cause?
- confusing indications or complete loss of back refection
- if the test specimen surface is curved byond limits the what is required?
- a plastic shoe to match the search unit face to the curved surface
- when an ultrasonic beam strikes a boundry between two different materials part of the energy is transmitted to the second medium and aportion is reflected.
- acoustic impedance
- the greater the differences in acoustic imedance across the interface the greater?
- the refection
- a thin film of liquid couplant material is required between the search unit and the part in or to ?
- displace air at the interface this allows transmission of ultrasonic enery into the test part.
- any liquid which will tansmit ultrasonic enery and meets what standards may be used?
- Able to wet both face and test part.
Is not corrosive or toxic.
Can be applied and removed easily.
Is homogenous and free of air bubbles.
- the ability of an inspection system to detect small discontinuities
- sensitivity is generlly rated how>
- the ability to detect a specified size and depth flat bottom hole
- all equipment and trasducers do not always produce identical indications for this reason what must be done?
- all inspections must be set up using a series of reference standards
- the ability of an inspection syste to separate signals from two interfaces colse togather in depth?
- contains all the elemets of the basic search unit including a connection for the signal cable?
- quarts, lithium sulfaate, and polorized ceramics are all what?
- crystal elements
- what is determined vy thickness of elements material?
- allow for attachment of signal connector and internal ground connector to crystal element
- serves to damp the ringing of the transducer element after it is excited?
- backing material
- These faces improve coupling on rough surfaces and prevent wear of the search unit face. they also reduce the amount of power available from the search unit
- wear face
- What is used to adapt search units for use in angle beams and surface wave inspection and or use on curves surfaces.
- wedges and shoes
- how many types of search units are there
- when a search unit is identified with angle only it idicates what?
- incedient angle only
- when transducer is identified with angle and material it indicates?
- refracted angle
- all immersion units use straight beam transducer why?
- angle beams will not propagate through liquid
- used to eliminate the near field?
- delay line tip
- uses two tranducer elements in one search unit
- dual element
- used to cover an range of refracted angles
- variable angle
- Freq range for USN-52?
- low .3-4 MHZ
- the usn-52 has an inspection range of?
- .2-200 inches in steel
- What type of screen does the usn-52 have and what are the power requirements?
- electroluminescent display
110-220 vac 50-60hz or 6 D-size Nicad lead acid or alkaline batt
- The MXU-715/E has a freq range of?
- 1-15 mhz
- the MXU-715/E has a inspection range of?
- .1-150 inches in steel
- How much does the MXU-715/e weight and what are the power requirements?
- 45 lbs
115/120 vac 60hz or 24 DC battery
- The usn-52 weight how much?
- 5.98lbs with batt and 3.1 without
- what is the purpose of standards?
- to establish inspection procedures.
to determain inspection sensitivity levels
to check equipment performance
to prevent repeatablity
- used to chec performace and caliration limits of equipment
- calibration standards
- ASTM CAL STANDARDS
- May be steel or aluminum
first 4 digits show material type.
5th digit shows DIA of flat bottom hole in 64th
last four digits show metal travel distand to the top of the FBH
- IAW blocks
- used for angle beam calibration and some straight beam applications
- miniture cal block
- used for angle beam cal and some straight beam
- ASME plate
- used for surface wave CAL
- Reference standards
- manufactured to evaluate indications from parts under test.
simulate defect size, shape, and location
made to part characheristics
limited to specific applications
employs EDM notches and drilled holes
- natural defect standards
- most accurate material and defect obtained but limited to specific inspections.
- Thickness measurement is for?
- Checking part thickness when back side of part is not accessable.
checking large panels in interior areas where a micrometer can not reach.
maintenance inspection for checking thickness loss due to wear or corr.
- What is the most common method for thinkness measurement?
- For pulse echo thickness messurent what unit should you use?
- What is the test range of pulse echo method for thickness?
- .005-20 inches
- For thickness measurments using pulse echo of a material that is .25 or less what is required?
- Delay line tip or dual element trasducer.
- what method of thickness meassurement applies continous electrical energy to the search unit?
- Resonance method
- By measuring the freq at which resonance occurs you can determain?
- Part thickness.
- As the test part thickness increases the fundamental and harmonics decrease and vice versa This is part of?
- resonance method
- A basic ultrasonic instrument that can also be used for thinkness measurments or?
- A instrument specifically designed for thickness being measured.
- thickness reference standards
- must be a known thickness
recommended to be of same velocity as material to be inspected
smooth surface is required
- Compression defects will appear where on the screen?
- Between the IP and BR
- shear mode 1st BR is from the?
- bottom corner of the part
- shear mode 2nd BR is from the?
- top corner of the part
- shear mode 3rd BR is from?
- the bottom corner of the part same as the first/
- when inspecting a wel you use a low freq L mode and?
- inspect 3-6 inches on either side of the weld
- Location of defect is noted on the screen and?
- compared to a known reflection
- Estimated by measuring signal ampitude of a defect inication displayed on the CRT is directly related to the amount of reflected sound returning to the trasnducer?
- To gather orientation of defect you do what?
- if possible evaluate from several different directions using angle and straight beam
- Several different types of indications will be encountered and can?
- cause confusion and false conclusions.
- Loss of and or multiple indications can be cause by what factors?
- Large grain size
dispersion of precipitate particles in material
lower fre will denerally reduce mulitple indications.
- Delamination can be detected by noting?
- a reduction in distance between BR mulitples
- Surface waves indications will move?
- towards IP as search unit is moved toward the edge
- surface waves can be generated when using?
- straight beam search units
- Surface waves created from straight beam search units can be?
- mistaken for discontinuities
- straight beams used near a boundry causes reflection and mode conersion this is know as?
- parallel boundaries
- major variables to consider when developing and coducting ultasonic inspections on bonded structures?
- Top skin material type and thickness.
adhesive type and thickness
- things to consider for honeycomb material?
- core material, cell size, thickness, and hieght
- things to consider for laminates?
- number of layers, layer thickness, and layer material
- unbonds or voids in an outer skin-to-adhesive interface?
- class I
- unbonds or voids at the adhesive to core interface?
- class II
- voids between layers of laminates?
- class III
- voids in foam adhesive or unbonds between the adhesive and closure member at core closure member joints?
- class IV
- water in core?
- class V
- Reference standards for composites?
- must be similar to test part with respect to material, geometry, and thickness.
Must contain bonds of good quality except for controlled areas of unbonds
- Composite ref standards must be bonded using?
- the adhesive cure cylces prescribed for the test part
- thru transmission inspection method for composites, Delamination or unbonds cause?
- blocked transmission of sound to the receiving unit.
- the minimum size unbond that can be detected is proportional to the?
- Receiving search unit.
- When perfroming thru transmission care must be taken to keep sending and receiving units in?
- tangent with each other
- This method is only applicable to honeycomb structures and is best applied to structures with single layer skin.
- employs an angle beam search unit because straight bean surch units may produce multiple echo signals from the layers that would interfere with echo signals fro the core?
- for pulse echo inspection of B/C/L what angle transducer should you use?
- 30-90 degrees
- The back refelction can generally be established by damping the opposite skin with your finger and noting a slight change in signal the back side of the core signal will be where?
- immediately in front of the damped signal
- what method is used when the best sensitivity is needed for detecting unbonds between the top sheet and the adhesive?
- An unbond below the first layer of adhesive will often not produce a rignhing signal because>
- the adhesive bonded to the top sheet will dampen the signal
- This inspection method of B/C/L is effective for laminates doublers and shin to closure member bonds when acesses to the back side is avalible?
- What is the special ultrasonic test equipment?
- The TTU-527/E compsite laminate tester
- the TTU-527/E test what?
- carbon graphite epozy composite laminates and indicates the presence of delamination by and aduble and visual alarm
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