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Definitions |
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allow for attachment of signal connector and internal ground connector to crystal element
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electrodes
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what is the purpose of standards?
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to establish inspection procedures.to determain inspection sensitivity levelsto check equipment performanceto prevent repeatablity
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What is inherent to all UT equipment?
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Dead zone
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Surface waves created from straight beam search units can be?
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mistaken for discontinuities
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unbonds or voids at the adhesive to core interface?
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class II
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shear mode 1st BR is from the?
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bottom corner of the part
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a thin film of liquid couplant material is required between the search unit and the part in or to ?
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displace air at the interface this allows transmission of ultrasonic enery into the test part.
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when a search unit is identified with angle only it idicates what?
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incedient angle only
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the greater the differences in acoustic imedance across the interface the greater?
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the refection
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What is the special ultrasonic test equipment?
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The TTU-527/E compsite laminate tester
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Reference standards
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manufactured to evaluate indications from parts under test.simulate defect size, shape, and locationmade to part characheristicslimited to specific applicationsemploys EDM notches and drilled holes
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coarse grain structures slatter and absorb what?
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sound energy
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A basic ultrasonic instrument that can also be used for thinkness measurments or?
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A instrument specifically designed for thickness being measured.
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For thickness measurments using pulse echo of a material that is .25 or less what is required?
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Delay line tip or dual element trasducer.
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to minimize the effects of surface conditions the part shall be free of?
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loose heavy or uneven scales machining or grinding particals or other loose foreign matter
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what is determined vy thickness of elements material?
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FREQ
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shear mode 2nd BR is from the?
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top corner of the part
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WHAT METHOD IS THE SEARCH UNIT PLACED DIRECTLY ON THE SURFACE?
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CANTACT
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how many types of search units are there
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3
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miniture cal block
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used for angle beam cal and some straight beam
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the incident angle of sound beam beyond which a specific refracted mode of vibration no longer exists?
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critical angle
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What travels approximately 1/2 the speed of logitudinal waves?
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shear
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WHAT TRANSFORMS ELECTRICAL ENERGY INTO MECHANICAL ULTRASONIC ENERGY AND RECEIVE AND TRANSFORM U/T ENERGY BACK INTO ELECTRICAL ENERGY
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TRANSDUCER ELEMENTS
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the MXU-715/E has a inspection range of?
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.1-150 inches in steel
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natural defect standards
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most accurate material and defect obtained but limited to specific inspections.
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The usn-52 weight how much?
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5.98lbs with batt and 3.1 without
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ASTM CAL STANDARDS
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May be steel or aluminumfirst 4 digits show material type.5th digit shows DIA of flat bottom hole in 64thlast four digits show metal travel distand to the top of the FBH
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things to consider for laminates?
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number of layers, layer thickness, and layer material
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HOW ARE DISCONTINUITIES DISCOVERD WITH THE THRU TRANSMISSION TECH?
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THEY BLOC PASSAGE OF SOUND.
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WHAT IS THRU TRANSMISSION?
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WHEN A TRANSMITTING SEARCH UNIT PLACED ON ONE SRUFACE AND RECIVING UNIT PLACED ON THE OPPOSITE SURFACE.
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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.
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acoustic impedance
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HOW ARE VIBRATIONS GENERATED?
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BY APPLING HIGH FREQ ELECTRICAL PULSES TO A TRANSDUCER ELEMENT CONTAINED IN A SEARCH UNIT.
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When perfroming thru transmission care must be taken to keep sending and receiving units in?
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tangent with each other
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Loss of and or multiple indications can be cause by what factors?
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Large grain sizeporsitydispersion of precipitate particles in materiallower fre will denerally reduce mulitple indications.
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MHZ IS RESPRESNTED AS?
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1 MILLION CYLCES PER SECOND.
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Compression defects will appear where on the screen?
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Between the IP and BR
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compression waves can propagate throught what materials?
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solids, liquids or gases
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HOW MANY MODES OF PROPAGATION ARE THERE?
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LONGITUDINAL(COMPRESSED), SHEAR(TRANSVERSE), SURFACE( RAYLEIGH), AND LAMB(PLATES)WAVES.
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contains all the elemets of the basic search unit including a connection for the signal cable?
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housing
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By measuring the freq at which resonance occurs you can determain?
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Part thickness.
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water in core?
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class V
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quarts, lithium sulfaate, and polorized ceramics are all what?
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crystal elements
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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?
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confusing indications or complete loss of back refection
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used to cover an range of refracted angles
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variable angle
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propagtion occurs when waves travel along a test part thinner than 4 wave lengths?
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Lamb(plate) waves
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What is the far field and what else is it know as?
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The zone beyond the near field. Fraunhofer zone
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serves to damp the ringing of the transducer element after it is excited?
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backing material
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THE DISTANCE AN ULTRASONIC WAVE TRAVELS PER UNIT TIME IS?
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VELOCITY
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all immersion units use straight beam transducer why?
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angle beams will not propagate through liquid
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ASME plate
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used for surface wave CAL
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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?
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pulse-echo
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when inspecting a wel you use a low freq L mode and?
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inspect 3-6 inches on either side of the weld
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the usn-52 has an inspection range of?
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.2-200 inches in steel
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Surface conditions can cause what?
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insufficant ultasonic energy reaching defects.Beam divergants or widing of the sound beam
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depth of penetration in coarse materials are?
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less
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What type of screen does the usn-52 have and what are the power requirements?
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electroluminescent display110-220 vac 50-60hz or 6 D-size Nicad lead acid or alkaline batt
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HOW IS ULTRASONIC ENERGY TRANSMITTED FROM A SEARCH UNIT TO A TEST PART?
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THRU COUPLING MEDIUM TO PREVENT AIR INTERFACE BETWEEN THEM.
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thickness reference standards
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must be a known thicknessrecommended to be of same velocity as material to be inspectedsmooth surface is required
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This method is only applicable to honeycomb structures and is best applied to structures with single layer skin.
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Pulse-echo
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used to chec performace and caliration limits of equipment
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calibration standards
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An unbond below the first layer of adhesive will often not produce a rignhing signal because>
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the adhesive bonded to the top sheet will dampen the signal
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For pulse echo thickness messurent what unit should you use?
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any
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Sound beams are not straight sided projections they?
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spread out and vary in intensity
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the angle at which sound is introduced into a part?
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angle of incidence
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WHAT IS PIEZOELECTRIC?
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THE ABILITY OF A MATERIAL TO CONVERT ELECTRICAL ENERGT INTO MECHANICAL ENERGY AND VICE VERSA.
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uses two tranducer elements in one search unit
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dual element
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the angle of incidence is equal to?
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Angle of reflection
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How much does the MXU-715/e weight and what are the power requirements?
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45 lbs115/120 vac 60hz or 24 DC battery
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Location of defect is noted on the screen and?
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compared to a known reflection
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thru transmission inspection method for composites, Delamination or unbonds cause?
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blocked transmission of sound to the receiving unit.
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voids between layers of laminates?
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class III
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Thickness measurement is for?
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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.
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the critical angle at which longitudinal and shear waves no longer exist?
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above the second critical angle
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The position of the sides and walls of the part can affect the test what part of variables affecting transmission is this?
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geometry of the part
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all equipment and trasducers do not always produce identical indications for this reason what must be done?
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all inspections must be set up using a series of reference standards
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the ability of an inspection syste to separate signals from two interfaces colse togather in depth?
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resoulution.
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the minimum size unbond that can be detected is proportional to the?
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Receiving search unit.
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Several different types of indications will be encountered and can?
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cause confusion and false conclusions.
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sound beams have properties similar to?
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Light beams
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shear mode 3rd BR is from?
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the bottom corner of the part same as the first/
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THE TOTAL DISTANCE TRAVELED PER UNIT TIME OR ACOUSTIC VELOCITY IS EQUAL TO?
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WAVELENGHTH TIMES FREQ
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Reference standards for composites?
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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
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What is the test range of pulse echo method for thickness?
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.005-20 inches
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snells law applys to what?
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incident and refracted angles
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what method is used when the best sensitivity is needed for detecting unbonds between the top sheet and the adhesive?
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ringing
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Defects need to be at least on dimension equal to or greater than what to dectect defects?
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1/2 the wave length side
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Surface waves indications will move?
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towards IP as search unit is moved toward the edge
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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
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wear face
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As the test part thickness increases the fundamental and harmonics decrease and vice versa This is part of?
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resonance method
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WHAT ARE THE MOST COMMONLY USED FREQ IN U/T?
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2.25, 5, 10 MHZ
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the TTU-527/E test what?
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carbon graphite epozy composite laminates and indicates the presence of delamination by and aduble and visual alarm
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To gather orientation of defect you do what?
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if possible evaluate from several different directions using angle and straight beam
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HOW IS TRANSMISSION OF U/T CHARACTERIZED?
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BY PERIODIC VIBRATIONS REPRESENTED BY WAVE MOTION.
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Greater penetration is aquired by?
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using lower frequencey
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The characteristic of surfaces to change the mode of propagation of acoustic energy from one mode to another?
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mode conversion
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WAVELENGTH IS EQUAL TO TRAVEL DISTANCE FOR?
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ONE CYCLE
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unbonds or voids in an outer skin-to-adhesive interface?
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class I
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for pulse echo inspection of B/C/L what angle transducer should you use?
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30-90 degrees
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straight beams used near a boundry causes reflection and mode conersion this is know as?
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parallel boundaries
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Surface waves can detect defects how fare below the surface?
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1/2 wave length below surface
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Why is beam spread important to calculate?
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ceacuse in certain inspection applications the spreading sound beam can reflect off of walls or edges and casue confusing signals.
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sensitivity is generlly rated how>
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the ability to detect a specified size and depth flat bottom hole
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things to consider for honeycomb material?
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core material, cell size, thickness, and hieght
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What spreads in the far field?
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beam spread
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greater sensitivity is aquired by using?
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Higher freq
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Surface waves can refelect around?
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curves
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voids in foam adhesive or unbonds between the adhesive and closure member at core closure member joints?
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class IV
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THE TOTAL NUMBER OF CYCLES PASSING A GIVEN POINT IN 1 SEC?
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FREQ
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what method of thickness meassurement applies continous electrical energy to the search unit?
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Resonance method
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What is used to adapt search units for use in angle beams and surface wave inspection and or use on curves surfaces.
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wedges and shoes
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used to eliminate the near field?
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delay line tip
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Area directly under a search unit to where the beam begins to spread?
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Near field Fresnel zone
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Sound reflects off an interface at the same angle at which it?
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travels through the material
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The change in direction of ultra sonic beam as it passes obliquely throug the interface between two materials with different acoustic velocities.
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refraction
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what consists of a transducer element mounted on a plastic wedge so waves ener the testpart at an angle?
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shear
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Near fields are not recommended for inspection due to?
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amplitude variations
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the shorter the post length the?
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Shallower the dead zone
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Freq range for USN-52?
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low .3-4 MHZBB- .4-10din- 2.0-8high- 3-10
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At a given freq the larger the transducer the?
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Less the beam spread and vise versa
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the ability of an inspection system to detect small discontinuities
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sensitivity
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Delamination can be detected by noting?
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a reduction in distance between BR mulitples
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Composite ref standards must be bonded using?
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the adhesive cure cylces prescribed for the test part
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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?
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damping
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IAW blocks
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used for angle beam calibration and some straight beam applications
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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?
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size
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any liquid which will tansmit ultrasonic enery and meets what standards may be used?
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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.is viscous
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when transducer is identified with angle and material it indicates?
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refracted angle
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The most sensitive wave of the three types?
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shear
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less beam spread means what?
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you have a high freq in the part and vice versa
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The intensity of the far field drops of exponentially as what?
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distance from the face of the transducer increases.
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The MXU-715/E has a freq range of?
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1-15 mhz
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characterized by particle movement perpendicular to the direction of the sound beam?
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shear or transverse waves
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a special type of shear wave in which the motion of the particles is confined to a thin layer of a solid?
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Surface wave or rayleigh.
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ULTRASONIC IS THE NAVY GIVEN TO?
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SOUND FREQ ABOVE 20,000 HZ THE RANGE A HUMAN EAR CAN NOT HEAR.
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What are characterized by particle movement parallel to direction of sound beam?
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Longitudinal or compression waves
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if the test specimen surface is curved byond limits the what is required?
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a plastic shoe to match the search unit face to the curved surface
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in contact scanning there is an area beneath search units which cannot be inpected due to large initial pulse?
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Dead zone
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What is the most common method for thinkness measurement?
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Pulse-echo
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surface waves can be generated when using?
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straight beam search units
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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?
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immediately in front of the damped signal
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IN WHAT TECHNIQUE ARE SHORT BURSTS OF ULTRASONIC ENERY ARE INTRODUCED INTO A PART AT REGULAR INTERVALS OF TIME?
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PULSE ECHO
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major variables to consider when developing and coducting ultasonic inspections on bonded structures?
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Top skin material type and thickness.adhesive type and thicknessunderling structure
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