Abstract: An apparatus for detecting breakage of a web of material traversing a machine for feeding the web, and a method for the same. The apparatus includes a housing for mounting three transducers, a first transducer adapted to periodically emit a burst of energy for a period of time, the burst of energy being reflected off an object and producing an echo signal. A second transducer adjacent to the first transducer receives a portion of the echo signal, and a third transducer also adjacent to the first transducer receives another portion of the echo signal. The strongest portion of the echo signal is used to detect whether the web is broken.

Abstract: An apparatus and method are disclosed for producing acoustical reflected images from selected planes within an integrated circuit package to detect flaws within the package.

Abstract: A multilayer object having multiple layers arranged in a stacking direction is evaluated for imperfections such as voids, delaminations and microcracks. First, an acoustic wave is transmitted into the object in the stacking direction via an appropriate transducer/waveguide combination. The wave propagates through the multilayer object and is received by another transducer/waveguide combination preferably located on the same surface as the transmitting combination. The received acoustic wave is correlated with the presence or absence of imperfections by, e.g., generating pulse echo signals indicative of the received acoustic wave, wherein the successive signals form distinct groups over time. The respective peak amplitudes of each group are sampled and curve fit to an exponential curve, wherein a substantial fit of approximately 80-90% indicates an absence of imperfections and a significant deviation indicates the presence of imperfections.

Abstract: A pulse-echo, immersion method for ultrasonic evaluation of a material which accounts for and eliminates nonlevelness in the equipment set-up and sample thickness variation effects employs a single transducer and automatic scanning and digital imaging to obtain an image of a property of the material, such as pore fraction. The nonlevelness and thickness variation effects are accounted for by pre-scan adjustments of the time window to insure that the echoes received at each scan point are gated in the center of the window. This information is input into the scan file so that, during the automatic scanning for the material evaluation, each received echo is centered in its time window. A cross-correlation function calculates the velocity at each scan point, which is then proportionalized to a color or grey scale and displayed on a video screen.

Abstract: A method and apparatus for non-contact determination of the weight per unit area and the thickness of thin materials. This involves directing an ultrasonic wave at the material and measuring the proportion of sound energy that passes through the material. The process is distinguished by the fact that the time intervals between the ultrasonic pulses are greater than the propagation time. At the receiver only the signals that exceed a certain amount and are shorter in duration than the propagation time are evaluated.

Abstract: In order to carry out the automated tapping of complex parts 10, such as helicopter blades, the surface to be inspected is subject to successive shocks using an impacting head 12 displaced in accordance with a given spacing or pitch. The sound produced by these shocks are collected by a microphone 16 associated with an acquisition circuit 18. At least two successive sound signals, which may or may not be consecutive, are compared in order to establish a fault diagnosis. The comparison and diagnosis are carried out by a neuron network or system, after the number of representative points of each sound signal has been reduced during a preprocessing involving a selection stage followed by a smoothing stage.

Abstract: A process and apparatus for visualization of internal stresses in solid mrials by an acoustic microscope (10) connected to an (5) having a circular or spherical transmitting and receiving surface (8) for transmitting ultrasonic waves to and receiving reflected waves from a sample (3) to be examined in a body of liquid (2), such as water, a motor drive unit (7) having a movable arm thereon (6) connected to the acoustic lens (5) for supporting and moving the for scanning the sample, the motor drive (7) being connected to the (10) for being operated thereby to perform the scanning, a computer (16) having a visual display unit (18), and an oscilloscope (20) for indicating the reflected waves.

Abstract: To improve and simply ultrasonic measurement of thin layers, an adaptive least-mean-square (LMS) implementation of a Wiener filter is used to deconvolve ultrasonic waveforms. This filter is structured as a finite-impulse-response (FIR) filter and solved using Widrow's adaptive linear combiner. The filter is implemented on a microcomputer with gating features for automated signal peak identification and measurement. The deconvolution process begins by assuming an impulse (the desired response) to a known input (the ultrasonic response). A transfer function is then determined that, when convolved with the response, results in the assumed impulse. The transfer function in this case is a long FIR filter typically requiring up to 128 taps to achieve acceptable results.

Abstract: A method and an apparatus for detecting and identifying a contaminant, such as ice, on the surface of a structure, such as a wing, are disclosed. The apparatus has a probe having a delay block with an interface apt to be placed flush with the surface of the structure and two faces at the same angle of inclination relative to the interface and having transmission and reception transducers each oriented perpendicularly to one of the faces. The block has an acoustic impedance lying in the range of 0.7 to 3.times.10.sup.6 kg/m.sup.2.s. It further has an energization and analysis unit for applying an electrical energization pulse to the transmission transducer and comparing the amplitude and the phase of the echo from the interface with a reference echo corresponding to no contamination.

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: This invention defines a combined inspection procedure using ultrasonic techniques for detection of hydrogen attack damage in material. The procedure comprises an initial scanning procedure for locating areas suspected of being damaged by hot hydrogen. The initial scanning procedure is a pattern-based backscattering test that provides a pattern which is classified as falling within at least one of four backscattering pattern category types. Follow-up test procedures based upon the pattern type are then performed. These tests include spectrum analysis, velocity ratio, spatial averaging backscattering, and frequency dependence for assessing whether the material has hydrogen attack damage and the extent of hydrogen damage in the suspect areas. Should hydrogen attack damage be identified, the velocity ratio and spectrum analysis tests can then be used to determine mechanical properties of the hydrogen attack damaged material.

Abstract: A method for the non-destructive evaluation of the integrity of wooden members, in situ, for example, embedded in the soil, employing the reflection of an acoustic wave off of the embedded end of the wooden member. The reflection is caused by the discontinuity in acoustic properties between wood and the supporting medium. The method allows the measurement, at one end of the member, of substantially the entire length of the wooden member without its removal. The acoustic wave is monitored in time and amplitude to provide indications of sound speed and attenuation, measurements which apparently are not unduly affected by coupling losses between the wooden member and its supporting matrix. These measured values may be empirically linked in an equation providing the integrity of the wooden member.

Abstract: Inclusions in a liquid flow, such as air bubbles in a blood flow, are detected by transmitting a signal through the fluid and receiving and interpreting the received signal based on the expected degree of attenuation for the liquid and the inclusions. The amplitude of the transmitted signal is automatically adjusted to maintain a constant average amplitude of the detected signal, thus compensating for changes in the detection environment. The average amplitude of the transmitted signal is controlled by integrating the received signal using an integrator with a time constant longer than the time constant of the expected inclusion signals, and comparing the integrated signal to a constant reference level.The presence of microbubbles is detected and a signal comprising a string of high frequency pulses is generated while the microbubbles are present.

Abstract: The presence of a crack in a material and the orientation of the crack is determined by placing a transducer on the surface of the material for propagating a shear wave for reflection off of the back wall of the material. The reflected signal is evaluated such that no signal or a weak signal indicates the presence of a crack. The transducer is then held in place and rotated while propagating a shear wave in order to determine the orientation of the crack. The reflected shear wave is then evaluated in the same manner.

Abstract: A method and apparatus for use in confirming hydrogen damage in a boiler tube comprises a pair of electromagnetic acoustic transducer coils which are mounted for movement toward and away from each other. An electromagnet produces pulses that generate acoustic beams across a chord and within the wall thickness of the boiler tube. For adapting to boiler tubes of different outside diameters, the transducers coils are mounted on a resilient member so that the coils can be pressed against the outer surface of coils having a variety of outside diameters. The angle of the acoustic beam between the coils must also be adjusted, however, and this is done by changing the frequency of energy applied to the coils.

Abstract: A process and apparatus for visualization of internal stresses in solid materials by an acoustic microscope (10) connected to an acoustic lens (5) having a circular or spherical transmitting and receiving surface (8) for transmitting ultrasonic waves to and receiving reflected waves from a sample (3) to be examined in a body of liquid (2), such as water, a motor drive unit (7) having a movable arm thereon (6) connected to the acoustic lens (5) for supporting and moving the lens for scanning the sample, the motor drive (7) being connected to the acoustic microscope (10) for being operated thereby to perform the scanning, a computer (16) having a visual display unit (18), and an oscilloscope (20) for indicating the reflected waves.

Abstract: A method and system for nondestructively testing in a continuous sequence a multiplicity of railroad track crossties of wood or concrete to determine the condition and life expectancy of each of the crossties and of the track as a whole. The system includes an electric pulse generator and a pair of transmitting and receiving transducers, which transducers are adapted to be brought into moving contact with the crossties at respective locations straddling desired test regions thereof, for example, the regions under a tie plate, for sending sonic mechanical pulses through that region of the crosstie from one transducer to the other. If desired, three pairs of transducers may be provided for simultaneously straddling both tie plates and a medial reference zone on each crosstie. The transducers and the pulse generator are carried by a vehicle riding on the track rails, along with a computer for processing/evaluating/storing/reproducing the test data.

Abstract: A method and apparatus for distinguishing between hydrogen damage in the wall of a boiler tube, and surface damage on the inside surface of the tube, comprises a pair of transducers which are spaced on the outer surface of the tube and which apply a refracted shear ultrasonic wave through a chord of the tube with a beam angle that is calculated from the outside radius and wall thickness of the tube. The transducers are first applied to an undamaged tube and an instrument connected to the transducers is adjusted to 80% of full screen height. The same transducers are then, applied to a suspected boiler tube. Any attenuation of the initially high amplitude below 12 dB indicates hydrogen damage as opposed to inner surface damage which has been found to produce a far lower attenuation.

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 assembly (1) is immersed in the water of a pool and placed in vertical position. Detection of the rods (6) of the assembly exhibiting cracks giving rise to leakage is ensured by transmission of ultrasonic waves along the length of each of the rods (6) and by measuring the attenuation of the ultrasonic waves due to the presence of water inside the rods (6) whose cladding is cracked. The ultrasonic waves are picked up after propagation on the cladding of the rods (6) of the assembly along their length, below the lower end fitting (5) in place on the assembly (1). The detecting device comprises an ultrasonic transducer (11) capable of transmitting ultrasonic waves along the length of the rod from its upper part, and a receiver probe (16) for the ultrasonic waves, placed under the lower end fitting (5).

Abstract: A non-contact caliper-type gauge particularly suited for measuring the thickness of a running web. In its preferred form, the system includes a pair of opposed scanning heads defining a gap through which the running web passes, the heads being adapted to transverse across the width of the running web. Each of the heads includes and ultrasonic transducer for directing energy at the web, detecting energy reflected from the face of the web nearest the respective transducer and determining the distance between a reference in the head and the facing surface of the web. One of the heads also includes a transducer, preferably an eddy current transducer, which operates on energy to which the web is transparent. The second transducer senses the distance between the heads thereby to determine any variations in the distance between the heads during traverse.

Abstract: A method of determining the fundamental viscoelastic properties of a viscoelastic material includes the steps of imparting a torsional stress in a viscoelastic material; measuring the relaxation of the torsional stress over time and converting the relaxation stress to a representative analog waveform; digitizing the representative analog waveform to produce a representative digital waveform; and, determining the frequency dependant fundamental viscoelastic properties of the material based on the shape of a portion of the representative digital waveform. To facilitate automating the method, the shape of the waveform may be analyzed to detect the start of a test, the end of the test, and whether the test is a valide test.

Abstract: A method and apparatus for non-destructive ultrasonic testing of tires is disclosed wherein an ultrasonic transmitter is positioned outside of the tire and applies pulses of ultrasound to the tire at a plurality of locations around the tire's circumference for transmission through the tire wall and receipt by an ultrasonic receiver located within the tire. The ultrasonic receiver generates signals in response to the received ultrasonic transmissions and a computer processes these signals to generate characterizing data from which defects in the tire may be determined. Signals representative of the defects are then processed to generate a graphic display illustrating the location of the defects with the tire.

Abstract: A method and an apparatus for observing operating state of a mechanical seal are disclosed. The apparatus comprises a sensor 1, amplifier 2,4, a root mean square value voltmeter 5 and a computer 7. Root mean square values of outputs of high frequency acoustic emission generated by a mechanical seal provided on a rotary machine are inputted in the computer 7 which performs operations to obtain a maximum value, a minimum value, a mean value and deviation of the continously measured root mean square values. The computer also computes the magnitude of each of the values, any tendency for variation thereof and their mutual relationships, whereby the operating state of the mechanical seal is judged in terms of damage of and the possibility of leakage of sealed fluid from the sliding surfaces of the mechanical seal.

Abstract: A non-destructive method for evaluating ropes, cables, and strands for flaws and tension is shown. The method permits detecting flaws by recognizing certain vibrational wave amplitude and distribution patterns resulting from striking a test subject with a transverse force. Tension on a test subject is calculated by measuring propagation velocity of the vibrational waves through the test subject. An apparatus is provided which produces vibrational waves in a test subject, measures the amplitude and time distribution of the waves, and displays the measurements for analysis.

Abstract: This invention provides an improved method for estimating the strength or stiffness of a piece of wood by measuring the longitudinal density profile of the wood. The density profile of the wood is determined by measuring the absorption or other modification of radiation at a sequence of local areas in the wood. The strength or stiffness estimation method identifies and quantifies those features in the wood density profile which describe two of the main wood factors that control overall wood strength or stiffness, i.e. the inherent (clear) wood strength or stiffness and the wood structural effect. The inherent wood strength or stiffness is mainly identified by the areas relatively constant density between knots, and the wood structural effect is mainly identified by the sharp density increases caused by knots. The strength or stiffness estimate for the wood combines these two factors.

Abstract: The present invention provides an ultrasonic method for measuring the size of a possible flaw in a solid mass, in which an ultrasound is transmitted perpendicularly to the searching surface of a solid mass being the object under measurement through a liquid, a ratio in sound pressure between a reflected wave of the ultrasound from the surface of the solid mass and a reflected wave from any flaw in the solid, and a distance from the surface of the solid mass to the flaw, derived from the difference in time of reception between the reflected wave from the surface of the solid mass and the reflected wave from the flaw in the solid mass, are taken as indices of evaluation, and these indices of evaluation are compared with a reference value obtained beforehand by measuring a test piece made of a same material as that of the solid mass, thereby determining the size of the flaw.

Abstract: The web in a high speed printing press passes between a transmitter and receiver, the former of which produces ultrasonic sound which the latter receives, after attenuation by the web, and the latter of which converts the sound into an oscillating electrical signal of corresponding frequency. This electrical signal, after being amplified and filtered, is impressed upon a peak detector and a comparator. The peak detector produces a constant potential equal to the amplitude of the peaks in the amplified signal, and this constant potential is reduced a predetermined proportion and is applied to the comparator as a reference potential. The comparator compares the reference potential with the amplified oscillating signal. The reference potential remains undisturbed even though the oscillating signal may momentarily drop due to the further attenuation of the sound caused by a splice moving through it.

Abstract: A computer-based defect recognition system for the automatic detection of parts defects includes an inspection knowledge base which enables automated defect inspections based upon a variety of nondestructive imaging tests, particular parts under test, the particular zone and region of the part, and the types of nondestructive imaging tests used. The knowledge database also provides for automated defect recognition to be applied to a wide variety of parts using a variety of nondestructive imaging tests while enabling flexible testing of different classified zones and regions of each part using the part-specific, zone- or region-specific, imaging test-specific inspection criteria, image processing algorithms, and computation algorithms.

Abstract: In a scanning acoustic microscope of the reflection type, in which an object is insonified with a series of ultrasonic acoustic pulses in accordance with a preselected scanning pattern and reflected acoustic echo pulses are received and employed to generate an initial electrical signal comprising a sequence of electrical pulses having amplitudes and polarities representative of the magnitudes and phases of the echoes, a directly readable unified interpretative display image is produced from the entire electrical signal; that image includes the usual scanning position and depth information determined by timing of the electrical pulses, together with complete transition information regarding the nature of acoustic impedance changes, based on both the amplitudes and the polarities of those pulses. A compared dual integration method and system, with related gating and display enhancement techniques, comprises the preferred embodiment.

Abstract: This ultrasound imspection method using the Born approximation simplifies the problem of characterizing 3-dimensional flaws of general shape by reducing it to a series of 2-dimensional tomographic image reconstructions. The reconstructed 2-dimensional images represent the 2-dimensional projections or shadows of the 3-dimensional flaw characteristic function which specifies the shape of the flaw. Each projection image is reconstructed independently using well developed computerized tomography techniques. If the shape of the flow is not too irregular or fine details are not of interest, only a few of these projection images are needed. The 3-dimensional flaw shape is reconstructed from the 2-dimensional projection images through a 3-D reconstruction process.

Abstract: In an ultrasonic inspection method and apparatus for inspecting the presence or absence of a defect in an object to be inspected by receiving as an RF signal a reflection beam of an ultrasonic beam emitted from a probe to the object and displaying data of the RF signal on a display unit, a maximum value indicative of a positive peak of the RF signal is detected, a maximum absolute value indicative of a negative peak of the RF signal is detected, a computation is performed for comparing in magnitude the maximum value indicative of the positive peak with the maximum absolute value indicative of the negative peak, and a computed value is displayed on the display unit so that the presence or absence of a phase inversion of the RF signal may be judged for deciding the presence or absence of a defect in the object.

Abstract: A method for testing timbers, such as railway sleepers, for disconformities or decay by inducing vibrations in the timber, for example with an impactor monitored by an accelerometer mounted on it and connected to a microprocessor and a display unit to give an indication of constant impact, detecting said vibrations by one or more transducers, amplifying and digitizing the transducer output and microprocessor-processing the digitized output to give an indication of disconformity or decay. One embodiment utilizes the comparison of the first half-cycle surface vibrations and shear vibrations. Another embodiment compares frequency domain information with a memory stored standard. The apparatus, comprising transducers, impactor, microprocessor and indicator is readily portable.

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: Ultrasonic test methods are used to measure the depth of intergranular attack (IGA) in a stainless steel specimen. The ultrasonic test methods include a pitch-catch surface wave technique and a through-wall pulse-echo technique. When used in combination, these techniques can establish the extent of IGA on both the front and back surfaces of a stainless steel specimen from measurements made on only one surface.

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: A mechanically amplified electroacoustic transducer system comprising an electroacoustic transducer having a vibrating element and an amplifier rod forming a probe extending from the transducer and in acoustically coupling contact with the vibrating element over a relatively small region thereof. The probe has a length which is approximately equal to the quarter wavelength or a multiple of the quarter wavelength of the acoustical energy generated by the transducer, the exact length of the probe being selected to provide optimum output from the system at a selected operation frequency of the transducer.

Abstract: A method and apparatus for monitoring operation of a valve is disclosed in which a signal, such as an alternating current electrical signal, is propagated through a fluid path defined by the valve. The occlusion of the fluid path is indicated by monitoring the propagation of the signal. The system is highly immune to electrical noise and to variations in fluid conductivity. The system is also well adapted for monitoring operation of valves having a plurality of ports. In installations employing a plurality of valves, as plurality of valve monitors can be used without mutual interference.

Abstract: Defects are detected in cylindrical rods, tubes or the like by a stationary transmission and receiving device arranged along the path which the test object passes axially by providing per test cycle a particular pulse being split for propagating bidirectionally azimuthally in the test object; both pulses are received repeatedly, once per circulation, so that a plurality of pulses appear with gradually declining amplitude; a sequence of burst signals, each of limited duration, is provided for purposes of timing and gating the burst being repeated per circulation on the basis of the expected and known propagation time between transmission and receiving portions; peaks of the received signal are detected once or twice per circulation and in synchronism with the timing and gating signal; the respective detected peak signals are digitized, summed in groups and the quotient of the sums is formed as quality indicator.

Abstract: A multi-viewing ultrasound transducer acquisition system for non-destructive evaluation, flaw detection and flaw reconstruction in materials. A multiple transducer assembly includes a central transducer surrounded by a plurality of perimeter transducers, each perimeter transducer having an axis of transmission which can be angularly oriented with respect to the axis of transmission of the central transducer to intersect the axis of transmission of the central transducer. A control apparatus automatically and remotely positions the transducer assembly with respect to the material by a positioning apparatus and adjusts the peGRANT REFERENCEThis invention was conceived and reduced to practice at least in part under a grant from the Department of Energy under Contract No. W-7407-ENG-82.

Abstract: An X-ray inspection system for manually or automatically performing digital fluoroscopy inspections and/or computed tomography inspections by X-ray examination of manufactured parts incorporates a computer system which automatically analyzes the inspected parts for flaws. The system includes apparatus for automatically positioning the parts in an X-ray machine for obtaining fluoroscopy and tomography views of the part and for acquiring data from the inspections at production rates. The system automatically identifies the location of rejectable flaws in the parts during the fluoroscopy scanning and subsequently identifies those locations for obtaining tomography scans, if the identified flaw location is questionable. The system can automatically reject parts containing flaws identified during the fluoroscopy inspections. This system operates in a real-time environment by providing analysis of one part while a subsequent part is being subjected to X-ray examination.

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 and apparatus for determining the location and size of structural defects in a body of solid material, particularly regions of thermoplastic deformation in semiconductor wafers. An acoustical focused beam generated by an ultrasonic transducer, having a pulsed frequency of at least 75 MHZ, is transmitted through the body to provide an attenuated signal pattern which manifests structural defects, such as slip planes which can result in wafer warp, as well as cracks, bubbles, foreign particles or segregation zones and internal interfaces.

Abstract: An ultrasonic sensor for non-invasive detection of air bubbles in a liquid flowing through a tube comprises two half-housings capable of being assembled together and two mutually opposed ultrasonic transducers, one installed in each of the half-housings. For acoustic coupling of the tube to the two mutually opposed ultrasonic transducers, each half-housing contains a chamber closed off by a flexible membrane and filled with a fluid highly transmissive of sound. The fluid displaced by the tube inserted between the two half-housings forces the membrane up in the form of a bulge on either side of the tube. In this way, an excellent contact is obtained between the chamber filled with sound-transmissive fluid and the tube. The membrane may be embedded into the side walls of the half-housings and cylindrically arched along the same.

Abstract: Apparatus and method for detecting voids and particulates in a fluid within a containing vessel. A diffuse ultrasonic signal is coupled into the fluid by a first transducer and the portion of the ultrasonic signal transmitted through the fluid is detected by a second transducer. The received signal is analyzed by a processor to determine the void fraction of the fluid responsive to the attenuation of the received ultrasonic signal. In addition, voids and particulates are detected by evaluating the increase in side-band energy of the received signal.

Abstract: The object of the invention is a method for the non-destructive testing of workpieces (14) or components with ultrasonics and a device for applying the method. The workpieces (14) are subjected in accordance with the through-transmission principle at the same locations (38) in succession with ultrasonic waves that differ by their opposing directions under conditions that are otherwise the same. The ultrasonic signals received in the two different sound directions are, provided they have different signal amplitudes, compared with given values obtained from a similar workpiece with defects in previously known depth in order to determine the depth of defect in the workpiece (14). If the sound absorption is complete, the ultrasonic waves continue to be applied in opposite directions to neighboring positions until ultrasonic signals are received whose differences are evaluated in order to determine the depth of the defect concerned.

Abstract: The invention relates to an ultrasonic test instrument for the nondestructive testing of materials. The instrument includes a transit time measuring circuit and an amplitude and time gate circuit. According to the invention, to measure the amplitudes and the corresponding transit times of a number of echo signals falling within a predetermined measurement range, the output of the amplitude and time gate circuit is connected to the input of a presettable counter which outputs a signal whenever the number of counted pulses is equal to the preset value of the counter. The counter output is connected to the transit time measuring circuit and by way of a second time gate circuit to the amplitude measuring circuit so that amplitude evaluation is carried out only during the time interval defined by the second time gate circuit.

Abstract: A method for the ultrasonic testing of bolts for incipient cracks emanating from a wall thickness discontinuity between thinner and thicker parts of the bolt, which includes placing an ultrasound transmitter and receiver in the form of a piezo-electric transducer on the periphery of the thicker part of the bolt with the discontinuity located in the near-field region, radiating longitudinal waves at an angle of 55.degree. to 70.degree. and transversal waves at an angle of 25.degree. to 35.degree. from the transducer in direction toward the discontinuity, and comparing the intensity of reflected transversal and longitudinal waves with an echo characteristic obtained from a test body corresponding to the bolt to be tested, having slots formed therein simulating incipient cracks of different depths, and an apparatus for carrying out the method.

Abstract: A method of monitoring a structure comprising the steps of:(a) transmitting a burst of acoustic energy through the structure from a transducer coupled to it,(b) detecting a received wave resulting from the burst at one or more transducers coupled to the structure, and(c) monitoring for any change in the structure after a given time (or event) by repeating the steps (a) and (b) with the coupling of the transducers being essentially unaltered, to detect a further received wave or waves; comparing the further received wave or waves with a corresponding reference received wave or waves; and determining for each comparison whether the received wave differs from the reference, any difference being indicative of the formation or growth of a defect in the overall acoustic path travelled by the acoustic energy.

Abstract: A transducer assembly and a system application wherein said transducer assembly may be used in the inspection of iron, steel, aluminum, as well as plastic materials as a homogeneous object in the form of a sheet, slab or bloom. Inspection is through use of ultrasonic acoustic energy propagated through ambient air. A coupling medium in the form of matching layers efficiently couple the transducer assembly to the ambient air.