Abstract: An objective and non-destructive test of the fused tang/commutator bar joints in an armature, that can be used on every armature being manufactured on an armature manufacturing line, as well as apparatus for performing that test, are provided. The armature is immersed in an acoustic coupling medium. Acoustic pulses, preferably ultrasonic pulses, are beamed onto the joint and the reflected pulses are measured. The quality of the joint can be determined by comparing the reflected amplitude to the known reflected amplitudes for joints of known quality. A testing station on an armature production line includes a mechanism for removing the armature from the production line, immersing it in the coupling medium, and rotating it as each joint in the commutator of that armature is checked.

Abstract: A method and apparatus of inducing vibrations and buzzes within a vehicle, e.g., from panel trim, provides a reliable and repeatable way to identify the sources of such vibrations and buzzes. According to the method, an FM transmitter modulates and transmits predetermined frequency signals to a standard FM receiver located in the interior of the car. The FM receiver receives and demodulates the signal, and then applies it to audio speakers also located within the vehicle. The output signal from the speakers induces sympathetic vibrations in vehicle components, allowing a tester to identify the sources of the vibrations and buzzes so that they may be corrected. The transmitter provides a means for a user to maintain a constant frequency or to vary the frequency within a predetermined range of frequencies. The frequency may be generated by digitally storing one complete sine wave in successive memory locations. The values can then be retrieved and converted to an analog signal.

Abstract: An ultrasonic interferometry technique for composite structures such as metal/polymer/metal structures exhibits high sensitivity to interfacial properties, even at usual ultrasonic wavelengths. A model for the ultrasonic response of multilayered media accounts for viscoelasticity. Results of numerical calculations point out scaling features for interfacial properties in terms of specific stiffness S. A method is provided for characterizing the interfacial adhesion in a multilayer composite in terms of the parameter S. The multilayer composite is ultrasonically irradiated with a pulsed signal to obtain a signal characteristic of the interfacial adhesion between the multilayers. A model is provided of the multilayer composite that includes at least two additional layers which model the behaviour of the interface between the composite layers.

Abstract: An apparatus and method for non-destructive examination of an interface within a body between two separate elements of the body wherein an acoustic microscope (124) has an ultrasonic transmitter (114) for directing ultrasonic waves at an angle to a body (1) and an interface (122) within the body between an outer part (3) and an inner part (2), an acoustic receiver (116) in spaced relationship to the transmitter (114) for receiving acoustic leaky waves from the interface (122), and a supporting device for supporting the transmitter and receiver for simultaneous scanning movement relative to the body at the same scanning speed. The body to be examined may be supported immersed in a liquid such as water (120) in a tank (121) so that the ultrasonic waves from the transmitter are directed at a predetermined angle depending on the materials of the separate elements and-pass through the liquid and the outer part before impinging on the interface in the body to be examined.

Abstract: A device for permitting evaluation of the acoustic impedance of liner designs used to attenuate noise in engine aircraft inlet and exhaust ducts, and in particular multiple degree of freedom designs of the type which include a porous facesheet followed by a backing depth followed by successive facesheet/backing depth combinations, includes a plurality of spacers of different thicknesses for varying the backing depths, and a movable plunger with a threaded adjustment mechanism for establishing the final backing depth. Gaskets and seals are installed at various interfaces to eliminate noise leakage paths. Two attachment bolts are used to hold the plunger assembly, face sheets, and spacers together, and an alignment disc positioned on the first facesheet is used to properly align an impedance tube waveguide on facesheet.

Abstract: A method for determining bond integrity of a sealed package has a lid bonded to a container rim by detecting flaws in the bond between the lid and the container. The method comprises: i) positioning the container rim between an ultrasonic transmitter system and an ultrasonic receiver system; ii) ultrasonically coupling the transmitter system and the receiver system to the container rim; iii) transmitting ultrasound waves from the transmitter system through the container rim to the receiver system; iv) generating a signal representative of the ultrasound waves received by the receiver system; and v) analyzing the signal for predetermined signal characteristics representative of a flaw in the bond to identify a flawed package seal.

Abstract: A measuring apparatus using an ultrasonic wave according to the invention transmits an ultrasonic wave pulse into a specimen, receives the echo reflected by the specimen and converts it into an electric signal. The components of the electric signal that represent the wave reflected by the specimen and contain data on the state of the specimen are extracted by a gate circuit. The components obtained by the gate circuit are converted into a power spectrum by a circuit for performing a Fourier transformation. The thickness of the specimen and/or the flaking state of the specimen can be determined from this power spectrum.

Abstract: The duplex tube (1) comprises a tubular core (2) and a cladding or covering layer (3) made from an alloy, the base metal of which is identical to the base metal of the alloy constituting the tubular core (2).

Abstract: A method of an apparatus for ultrasonic inspection of multi-layered structures having acoustic transmission (I, III, V and VII) and reflection (II, IV, VI and VIII) frequency bands. Variations in one or more parameters of specific layers are largely restricted to specific frequency bands of said layers. By analyzing transmitted or reflected signals with respect to the frequency bands of the structure, interpretation of signals due to parameter variations as caused by voids, inclusions or delaminations can be effectively eliminated. The method is preferably used for the inspection of laminated structures consisting of metal layers bonded by fibre reinforced resin layers.

Abstract: There is provided a programmable receiver for detecting signals reflected from, or transmitted through, a material for analyzing flaws in the material, having a circuit for dividing the signals into a multiplicity of separate, independent sections for selective evaluation of waveform portions as contained in each of the sections. A method for detecting and analyzing flaws in materials is also provided.

Abstract: A method and apparatus are provided for indicating disbonds in joint regions. A critical bondline region is located between a first material and a second material having a higher acoustic impedance than the first material. A form member having an acoustic impedance which is substantially similar to the first material has a first face which is form fitted to a surface of the first material opposite to and non-parallel with the critical bondline region. The form member has an opposite second face which is shaped to be parallel to the critcal bondline region. Transducers are acoustically coupled to the second face of the form member to generate an ultrasonic tone burst through the acoustically similar form member and first material which is reflected by the critical bondline region. This reflected tone burst is received and a resulting signal is compared with a normal signal for no disbond to determine the presence of an unacceptable disbond.

Abstract: A flexible mounting (2) having a ring made of elastomeric material (3) fixedly engaged between an inner metal collar (4) and an outer metal collar (5) is mechanically stressed so that it undergoes a gradual elastic deformation corresponding to a relative displacement of 15 mm between the collars in a period of 20 seconds. Acoustic transducers (7) carry out the detection of the acoustic emissions occurring within the mounting itself and caused by structural instabilities arising in the flexible mounting while it is deformed. The acoustic transducers convert the acoustic emissions to electric signals that, after suitable amplification and discrimination, provide a reliable quality evaluation of the mounting being tested.

Abstract: Method and apparatus are described for using stress wave measurements in the estimation of quality of finger joints in wood and quality of lumber, where quality is typically defined as strength. Application and measurement of stress waves in the transverse direction of the material allows localized measurements to be made, and features developed from this information are used in the quality estimation. A feature is a quantifiable characteristic developed from stress wave signals which can be used either by itself or in combination with other features to estimate quality. Examples of features include the propagation velocity of a stress wave, the attenuation of a stress wave, the difference in stress wave propagation times measured at different locations along the lumber, and the effects on amplitude and phase of frequency components of a stress wave. Treating features together as a feature vector and as input to an estimator function, estimated quality can be evaluated.

Abstract: The duplex tube (1) comprises a tubular core (2) and a cladding or covering layer (3) made from an alloy, the base metal of which is identical to the base metal of the alloy constituting the tubular core (2).

Abstract: A non-destructive method for testing quality of at least one bond which physically and electrically couples a package lead to an integrated circuit. A thermal gradient is created across the at least one bond which causes heat transfer thru the at least one bond. Heat transfer is measured which is proportional to area at a bond interface. The measured heat transfer thru the at least one bond is compared with heat transfer data taken under substantially equal conditions of known good bonds thereby determining quality of the at least one bond. The heat transfer is indirectly measured by creating a mechanical vibration at an input area and by measuring the time it takes the mechanical vibration to reach an output area after the mechanical vibration has traveled through the at least one bond.

Abstract: An ultrasonic adhesion/dehesion monitoring apparatus for monitoring the quality and/or adhesion/dehesion between first and second substrates comprising: (a) an ultrasonic source for transmitting ultrasonic energy to at least first and second substrates; (b) acoustic transducer means proximate to the ultrasonic source and/or the substrates; and (c) monitor means coupled to the acoustic transducer means for monitoring the ultrasonic signal from the ultrasonic source. Also disclosed is a method for monitoring the quality and/or adhesion/dehesion between first and second substrates in the ultrasonic adhesion/dehesion monitoring apparatus.

Abstract: The strength of a join between a ceramic and an associated non-ceramic is determined using an ultrasonic microscope. A converging ultrasonic beam is radiated against a point on a surface of the ceramic, said point being a predetermined distance away from the join between the ceramic and the associated non-ceramic. Data on the intensities of interference waves at respective predetermined variations of the relative distance between a probe of the ultrasonic microscope and the ceramic are collected. The residual stress at the point is calculated on the basis of the cycle of echo intensities of the interference waves for the respective predetermined variations of the relative distance. The strength of the join is then determined on the basis the residual stress.

Abstract: Acoustical radiation is generated and applied to the bonding interface between a radiation transmission material and a radiation attenuating material to determine adhesion quality by extraction of data from a response signal produced by echoes reflected from both the interface and the radiation entry surface on the radiation transmissive material exposed to the generated acoustical radiation. Signal phase cancellation between the echoes from the entry surface and bonding interface produce a signal signature from which the quality of bonding is evaluated. By partial attenuation of the echo from the entry surface, the signature is maximized.

Abstract: A method and apparatus is disclosed for the non-destructive measurement of die-attach quality in packaged integrated circuit. The apparatus is used in a production line and uses acoustical pulses to generate signals from within the integrated circuit indicative of the die-attach quality.

Abstract: A method and apparatus for nondestructively determining fiber volume fraction and resin porosity of a composite material constructed of at least two different constituent materials wherein the following parameters of the composite material to be tested are known: density, elastic moduli of the constituent materials and layup sequence. Two acoustic waves of different polarizations are propagated through the composite material and the acoustic waves propagated through the composite material are sensed and the velocity of each of the two acoustic waves, V.sub.1 and V.sub.2, are determined. The thickness of the composite material is determined. The fiber volume fraction and resin porosity of the composite material are then determined using the velocities, V.sub.1 and V.sub.2, the thickness and known parameters of density, elastic moduli of the constituent materials and layup sequence.

Abstract: Leak detector arrangement for the detection of small openings in car bodies or other enclosures or containers which may permit undesired passage of water, fumes, or other fluids in which phase coded or linearly frequency modulated sound waves are directed towards potential leak areas. The portion of these waves which pass through the leak openings is received, and these signals are processed so as to discriminate these leak signals from other sound waves normally entering the receiver from other parts or from other sources. The discriminated signals are compared with a threshold so as to determine the absence or presence of a leak.

Abstract: The invention is a method for the on-line nondestructive determination of the internal bond strength of composite panel products. The method involves impinging an ultrasound pulse against the panel by a first transducer and receiving a transmitted pulse at a second transducer. The received signal strength, temperature and panel thickness are entered into an algorithm from which the internal bond may be calculated. Preferably the receiving transducer is located on the opposite side of the panel and displaced somewhat from the first transducer. The inclusion of temperature and panel thickness as independent variables greatly improves the accuracy over that available from uncorrected ultrasound testing.

Abstract: A method of monitoring bonding parameters during a bonding process. The method is based on the object of continuous monitoring of bonding parameters in order to provide adjustment of bonding machines and thereby increase the reliability of the bonded connections. A bonding force is measured by a wire strain gauge attached to a bonding arm and an ultrasound amplitude is measured by a piezo-electric sensor secured to the bonding arm. The method can be used with all bonding machines which work with ultrasound.

Abstract: Measuring vibrational frequency of a pin attached at one end by collimating two laser beams onto the pin and back scattering the beams. The back scattered frequency is modulated by doppler effect and is heterodyned with the original beam frequency to produce a signal representative of each modulating frequency. The representative signals are summed together and also subtracted from one another. The summed and subtracted signals are representative, one of the vibrational frequency of the pin and the other of the degree of focussing accuracy of each laser beam onto the pin.

Abstract: An ultrasonic inspection probe for locating and sizing flaws in the radius region (20) and adjacent areas of a laminated structure (10), such as a composite "T" stiffener (30). The probe includes a plurality of shoes (48, 50, 52, 54, 56, 58) that are arranged for coordinated movement relative to the part under inspection. Each shoe includes a plurality of ultrasonic transducers that are arranged in predetermined adjacent relationships to one another and operated in timed sequence in one or more through-transmission, pulse echo or loss-of-back modes to effect an ultrasonic scan in one direction through the part while the transducers are moved together in another direction along the part. Inspection of the radius region is effected using combinations of angular pulse echo inspection (PEF, PEA, LL45P, RL45P), "radius-to-radius" through-transmission inspection at an angle through the radius region (RTT, RTR, L37.5T, L37.5R, U37.5T, U37.

Abstract: The invention provides a method and apparatus for non-destructive testing of bonded structures, such as laminated or composite materials. A beam of coherent light is directed successively onto each point of the object. The reflected beam creates a speckle pattern. The pattern is observed once while the object is stationary and once while the object is mechanically excited. If the point being observed is free of defects, the speckle pattern will be substantially unaffected by the vibration of the excited object. If the point is defective, vibration will blur the speckle pattern. The entire object is scanned, point by point, and the results of the comparison of the speckle patterns obtained for each point are stored and displayed. In another embodiment, the object is made to vibrate continuously, and the apparatus determines whether the speckle pattern is sharp or blurred, for each point being scanned.

Abstract: In order to guarantee a constant quality of assembled modules, bonders in accordance with the object underlying the present invention must be monitored and potentially adjusted in suitable time intervals with respect to bonding force, ultrasound amplitude and bonding time. Further, it is an advantage that the present invention has a flexible format. In accordance with the invention, the registration of the measured values ensues with a mobile, piezo-electric sensor on a table of the bonder which is no higher than integrated circuits normally processed thereon. Fields of utilization cover all ultrasound bonders for integrated circuits.

Abstract: Apparatus and method for determining the steady state flow resistance of face sheets on fully assembled acoustic duct liners. Resistance is measured by subjecting the liner to a sinusoidal acoustic pressure field at the face sheet surface. The pressure field is applied through a cylindrical waveguide and is measured by a pressure transducer flush mounted on the inside of the waveguide near the liner face. A second pressure measurement, obtained by a similar transducer positioned further from the face, is combined with the first measurement to calculate the acoustic resistance for the excitation frequency. If the excitation frequency coincides with the resonant frequency of the liner configuration, then no significant pressure exists on the back surface of the liner face sheet. For this condition the root mean square (rms) pressure measured at the face sheet is equated to the static pressure drop used to obtain the steady state flow resistance.

Abstract: The invention is a method for the on-line nondestructive determination of the internal bond strength of composite panel products. The method involves impinging an ultrasound pulse against the panel by a first transducer and receiving a transmitted pulse at a second transducer. The received signal strength, temperature and panel thickness are entered into an algorithm from which the internal bond may be calculated. Preferably the receiving transducer is located on the opposite side of the panel and displaced somewhat from the first transducer. The inclusion of temperature and panel thickness as independent variables greatly improves the accuracy over that available from uncorrected ultrasound testing.

Abstract: In a method of flaw classification on and in welds of planar or arcuate plate-shaped workpieces of uniform thickness by means of ultrasonics, the expected flaw areas of the workpiece are pre-examined manually and are then examined systematically using the ultrasound echo image method in separate cross-sectional planes. A B-scan is thus generated, and changing the position of the transducer on the workpiece and/or the transmitting direction enables defects to be located by calculating the delay time of ultrasound waves in the go-and-return directions within the workpiece under consideration of possible reflections at the rear side (8) of the workpiece. For defining the test conditions, part-specific parameters are considered, such as weld type and weld shape (e.g., double-V-weld and bell seam), weld geometry (e.g. seam angle), and part characteristics (e.g.

Abstract: A flexible U-shaped channel is abutted against a surface to be measured, thereby forming an acoustic duct, with the surface forming one wall of the duct. An acoustic source injects sound waves into the duct traveling parallel with the surface in order to establish a standing acoustic wave. Measurements of acoustic pressure at several points allows one to compute k.sub.y, the acoustic wave number normal to the surface, and from k.sub.y to compute the acoustic impedance of the surface.

Abstract: The ultrasonic energy applied to a workpiece to be welded in an ultrasonic welding operation, over a predetermined welding time, is measured by processing the output of a load cell beneath the workpiece to produce a signal voltage for comparison with a predetermined reference voltage corresponding to the accumulated ultrasonic energy that should have been applied to the workpiece during said predetermined time to satisfactorily weld the workpiece. A one-shot timer is started at the commencement of the welding operation. If the comparison reveals that signal voltage has reached the reference voltage before the timer has run out, a success signal is generated to indicate the completion of the welding operation.

Abstract: An object to be inspected which is jointed to a circuit board is vibrated in a contactless manner by applying a gas jet or a magnetic force to the object, a laser beam is irradiated on the object, and a laser beam reflected from the object is detected by a linear sensor to observe a laser speckle pattern for the object. Quality of a joint junction state of the object is judged from the laser speckle pattern.

Abstract: A method of inspecting a component in which the surface of the component is scanned with a loud speaker, the sonic output of which is arranged to be at such a frequency or frequencies as to cause any cracks, fractures or unbonded regions within the component to generate transient stress wave emissions. An acoustic emission transducer is attached to the component surface so as to detect any such transient stress wave emissions and thereby provide evidence of the existence of any such cracks, fractures or unbonded regions.

Abstract: A method and apparatus for detecting disbond in laminar workpieces. Energy is transmitted to a workpiece (8) by repetitive impacts. A transducer (12) converts energy emitted from the workpiece (8) to an electrical signal. The energy emitted in response to each of the repetitive impacts is analyzed. After filtering out the DC component (20) and amplifying the signal (30) the maximum amplitude of the energy from each impact is selected (50) and passed to a sample and hold circuit (60). The piecewise linear output of the sample and hold circuit (60) is passed through a low pass active filter (70) prior to recording on a strip chart recorder. The strip chart record is analyzed to ascertain areas of the workpiece (8) having defective clad bonding (7).

Abstract: Apparatus is provided for monitoring the bond condition of a fine aluminum wire being ultrasonically bonded to an electrode pad. The apparatus comprises a counter for generating a start and stop signal indicative of a predetermined plurality of cycles from the ultrasonic generator of the ultrasonic bonder. A stable source of pulses is applied to a second counter which is started and stopped by the start and stop signal. The count stored in the second counter is read out to a microprocessor and is indicative of the frequency of the ultrasonic generator during the bonding operation. A plurality of frequency readings are taken and measured during the formation of an ultrasonic wedge bond and this information is employed to calculate a bond quality rating which accurately predicts whether a good bond has been made or some condition exists indicating that a good bond has not been made.

Abstract: Apparatus and method for testing structures by impact. The structure is struck by an impactor associated with a force transducer the output of which is related to the force which the transducer experiences on impact and encompasses a frequency range including the lowest frequencies (typically approaching zero frequency, see FIG. 3) which that force contains to any substantial degree. A test spectrum of the force including that full range of frequencies is produced by a Fourier transformer in a form suitable for automatic comparison, and is then so compared with a reference spectrum typical of impact with a reference structure, and a signal is produced indicating fit or lack of fit between the test and reference spectra.

Abstract: A system for non-destructive testing of metallic materials and for, in particular, welding seams. An ultrasonic sensor is employed and ultrasonic defect signals are producted according to the pulse echo method. The ultrasonic defect signals are digitized and the digitized signals are combined with signals corresponding to longitudinal positions along the welding seam. A defect curve is produced form the data resulting from combining the digitized signals with the signals corresponding to longitudinal positions along the welding seam. The resulting defect curve is compared with data from a catalog of classes of defects. The system eliminates the need for manual ultrasonic reinspection of presumed welding defects.

Abstract: A method and apparatus for the non-destructive testing of materials, particularly composite structures and other such laminated materials, which comprises repeatedly impacting the material being tested with a precisely regulated force having a pre-determined magnitude. The response generated by the material is detected by a sensor and a proportional electrical signal is generated. The electrical signal is compared with a stored electrical signal previously generated in response to impacting a defect-free reference material with the same precisely regulated pre-determined force. A difference in frequency and amplitude between the two compared electrical signals is indicative of a defect in the material being tested.

Abstract: The disclosure describes a method for checking an insulative condition of an insulated winding used in an electrical appliance comprising applying an external mechanical force to said insulated winding to give vibrating frequency to the same for its examination; detecting the frequency behavior to be generated in said insulated winding in the form of electrical signal outputs; and electrically processing the signals for judging deterioration occurred in said insulated winding.

Abstract: The invention relates to a convertor for converting electrical vibrations into mechanical vibrations for non-destructive testing of objects, in particular bonded joints between two or more sheets or between sheets and a honey comb structure. Said convertor comprises a polycrystalline, piezo-electric disc, with mutually insulated electrodes on both head faces. The disc is secured in a supporting element by a suspension with a resilient member pressing centrally through a metal pin against the internal head face of the disc. The supporting element is movably installed into a holder such that the supporting element can be moved from a retracted position in the direction of the extended position until such a position is reached that the piezo-electrical disc is pressured against the object to be tested with a predetermined force.The invention also relates to a method for using the convertor.

Abstract: A method and a system for testing the bonding of foam insulation (22) attached to metal. The system involves the use of an impacter (10) which has a calibrated load cell (12) mounted on a plunger (14) and a hammer head (16) mounted on the end of the plunger (14). When the impacter (10) strikes the insulation (22) at a point to be tested, the load cell (12) measures the force of the impact and the precise time interval during which the hammer head (16) is in contact with the insulation (22). This information is transmitted as an electrical signal (20) to a load cell amplifier (28) where the signal (20) is conditioned and then transmitted to a Fast Fourier Transform (FFT) analyzer (34). The FFT analyzer (34) produces energy spectral density curves (power plotted against frequency in Hertz) which are displayed on a video screen (39). An operator, by observing the frequency point at which the curve terminates, may determine the quality of the bond.

Abstract: An electro-mechanical impacting device (10) for testing the bonding of foam insulation (22) to metal (26). The device lightly impacts foam insulation (22) attached to metal (26) to determine whether the insulation (22) is properly bonded to the metal (26) and to determine the quality of the bond. A force measuring device, preferably a load cell (12) mounted on the impacting device, measures the force of the impact and the duration of the time the hammer head (16) is actually in contact with the insulation (22). This information is transmitted as an electric signal (20) to other elements of the invention's associated system (not part of this invention) which are capable of conditioning the signal and evaluating it electronically in order to provide a visual display on a video screen. This allows an operator to make decisions relating to bonding and the quality of bonding.

Abstract: Apparatus and method for calculating and displaying the location of a defect inside a test specimen which has been detected by angled, ultrasonic beam, nondestructive inspection techniques are disclosed.

Abstract: An ultrasonic technique for remotely inspecting a body is described. A transducer (14), capable of generating and detecting ultrasonic signals, is coupled to the body. An ultrasonic signal (A.sub.o) is launched by the transducer (14) into the body (e.g. 10, 11) and is reflected by any imperfection (e.g. 12) therein. The effects of variations of the transmission coefficient between the transducer and the body are substantially eliminated by intentionally cutting a predetermined calibration notch (22) into the body under test. The analysis of the reflected ultrasonic signals at the notch (22) and at any imperfection (e.g. 12) within the body gives an indication of the quality of the body independently of the transducer/body transmission coefficient.

Abstract: An ultrasonic probe for inspecting the interface between the walls of a double-wall tube comprises a cylindrical body member having two cavities axially spaced apart thereon. The probe is placed in the tube and ultrasonic energy is transmitted from a transducer in its body member to a reflector in one of its cavities and thence into the inner wall of the tube. A second transducer in the probe body member communicates with the second cavity through a collimation passage in the body member, and the amount of ultrasonic energy reflected from the interface between the walls of the tube to a second reflector through the collimation passage to the second transducer depends upon the characteristics of said interface.

Abstract: The bond between a structured copper heat sink member and a semiconductor wafer is inspected for voids and unbonds by a focused ultrasonic pulse transmission method. The small focused spot of ultrasound is transmitted along the structured copper strands and is attenuated in the lateral direction. The absence of a received pulse or a significantly reduced amplitude signal, as the assembled device is scanned with acoustic pulses, indicate flaws in the bond.

Abstract: Initiation and propagation of cracks in materials is detected and monitored by (a) adhering an acoustical emitter to the area of the material to be monitored, and (b) monitoring for acoustical signals emitted by the adhered emitter, said signals produced by cracks in the material initiating in or propagating into the acoustical emitter. An acoustical emitter such as brittle plastic, glass rods or strips and metal such as tin or cadmium can be used.

Abstract: A percussion technique is described with which an impulse is applied to an element to bounce it off the inner surface of a casing cemented in a borehole. The movement of the element is automatically measured to produce information from which the bond between the casing and cement behind the point of impact of the element can be evaluated. In accordance with one embodiment, the cement bond evaluation is automatically derived by comparing impact and rebound velocities of the element such as by generating a coefficient of restitution of the bouncing element. In another embodiment, the contact time of the element with the casing is measured to derive an indication of the quality of the cement bond.

Abstract: Disclosed is a nondestructive test device for detecting a flaw proximate to a welded seam in a pipe, including an electromagnetic acoustic transmitting transducer for generating a horizontally polarized shear wave in the wall of the pipe, a high frequency generator operatively connected to the transmitting transducer for energizing the transducer, an electromagnetic acoustic receiving transducer for responding to a horizontally polarized shear wave within the wall, an amplifier operatively connected to the receiving transducer for boosting the response signal of the transducer, and an indicating instrument for receiving and displaying the amplified response signal. In the test method disclosed, a horizontally polarized shear wave is generated in the wall, the pipe is monitored to detect a reflected horizontally polarized shear wave, and a time-dependent representation of the amplitude of the reflected wave is displayed.