Showing papers on "Ultrasonic testing published in 1980"

Ultrasonic Wave Propagation and Anisotropy in Austenitic Stainless Steel Weld Metal

Abstract: The propagation of ultrasonic waves in stainless steel weld metal, an anisotropic medium, is examined. Significant variations in ultrasonic velocity as well as in attenuation have been observed for dif- ferent propagation directions. Elastic-constant data have also been ac- quired from single crystals of stainless steel and used in a simple model to describe the weld metal. From this model, velocities of sound as well as beam deviations can be predicted. The effect of anisotropy on flaw detection in stainless steel welds is discussed and examples are given. The current work is compared with recent literature on this subject.

Cylindrical transducer ultrasonic scanner

Abstract: An ultrasonic image of improved resolution is obtained by utilizing separate transducers for transmission and reception of ultrasonic pulses utilized for imaging, one transducer being a cylindrical or simulated cylindrical transducer having a line focus and the other transducer being aimed along the focus of the first transducer An area to be imaged may be scanned by rotating and/or traversing the transducers as a unit

Scanning ultrasonic probe

Abstract: The invention is an ultrasonic testing device for rapid and complete examination of the test specimen, and is particularly well suited for evaluation of tubular test geometries. A variety of defect categories may be detected and analyzed at one time and their positions accurately located in a single pass down the test specimen.

Ultrasonic measurement of material properties

Abstract: The state-of-the-art of ultrasonic methods is reviewed with reference to the basic measurements, signal acquisition and processing, strength property and morphological condition measurements, and industrial applications. The emphasis is placed on techniques that indicate quantitative ultrasonic correlations with material strength and morphology relevant to the reliability of load-bearing structures.

Ultrasonic apparatus and method for measuring the characteristics of materials

Abstract: Ultrasonic apparatus and method measures the characteristics of materials by sensing changes in the impedance to applied drive excitation of an ultrasonic probe using a crystal sensor that is integral with the ultrasonic transducer.

Apparatus and method for ultrasonic inspection

Abstract: In a new method and apparatus for ultrasonic inspection of objects each inspection device of the apparatus is fed by gravity with a supply of a liquid coupling medium, from which the device produces a flowing liquid column that is directed at the object. The device mounts a focusing ultrasonic transducer that generates an ultrasonic beam in the liquid focused at a downstream point not less than about 5 cm from the oscillation generating surface. The external envelope of the ultrasonic beam is contained wholly within the external envelope of the liquid stream with a separation between them at least until the object is impinged by the liquid column. The liquid feed is made as non-turbulent and entrained bubble-free as possible to avoid the generation of unwanted background noise and spurious signals. The increase in distance through which inspection can be effected simplifies the application of the method to testing pipe wall and laminar thickness and to the testing of bulky bodies such as aeroplane wings. It also permits the application of the method and apparatus to the in situ testing of the wall thickness of well pipes.

A tethered float radiometer for measuring the output power from ultrasonic therapy equipment

Abstract: A simple instrument for determining the total power from ultrasonic therapy equipment is described. It employs a novel method of measuring the radiation force exerted by the ultrasonic beam radiated by the equipment into a water-filled test tank, and offers a number of advantages over established techniques with regard to simplicity, sensitivity and ease of use. Further development of the device now in progress could provide a simple means of measuring ultrasonic power at the much lower levels normally associated with diagnostic equipment.

Ultrasonic Measurement of Respiratory Flow

Abstract: We review ultrasonic measurement of fluid flow with emphasis on ultrasonic pneumotachometers (UPTM's). For PTM's we discuss specifications such as dynamic range, resistance, and frequency response. We review fluid flow principles and point out the problems of nonultrasonic PTM's For UPTM's we describe transducer construction, attenuation versus frequency, reflection at interfaces, and acoustic field patterns. We present four principle types: 1) time of flight, 2) sing around, 3) phase shift, and 4) phase-locked frequency shift. For each, we detail principles, advantages, disadvantages, and potential for future development.

Ultrasonic test apparatus and sweep voltage generator for use therein

Abstract: The results of the non-destructive testing of objects with a beam of ultrasonic energy is enhanced by generating display control signals commensurate with a precisely defined region in the test object. These region related signals may be displayed as a "gate" bar on the screen of a cathode ray tube simultaneously with the display of echo related signals. Echo related signals having a magnitude greater than a threshold level, as also defined by the "gate" bar, are detected and may be employed to energize an alarm.

Design and Construction of an Ultrasonic Pneumotachometer

Abstract: Pneumotachometers (PTM's) measure the instantaneous rate of volume flow of respired gas. Currently existing PTM's suffer from a number of limitations. Ultrasonic PTM's are superior in a number of ways to these PTM's, but have not yet achieved acceptance due to instabilities and inaccuracy. We investigated a new design which used cylindrical shell transducers to generate ultrasound and measured phase shift as a measure of transit time change due to flow. The results were linear and predictable over a wide dynamic range using a single gas under controlled conditions, but deviated from expected values when the gas composition changed. We evaluate our original model of UPTM operation and revise it in light of our findings.

Quantitative Characterization of Tissue Using Ultrasound

Abstract: Present medical ultrasound systems are based on energy detection methods and therefore only utilize echo intensity information. However, phase, as well as spectral, information is recorded by the transducer, which is a pressure sensitive device, but is not utilized in present display or measurement schemes. This additional information may be of diagnostic significance since the interaction between sound and tissue is exceedingly complex, since many types of tissue can be categorized in terms of their acoustical properties, and since changes in tissue acoustical properties can be correlated with specific pathological states. Thus, in principle, in vivo techniques could be devised which would extract and separate the medically significant features of the ultrasound interactions with tissue and would display ultrasonic tissue signatures appropriate for a differential diagnosis. The development of such quantitative techniques for the measurement of ultrasonic tissue parameters and/or the display of ultrasonic tissue signatures is known as ultrasonic tissue characterization. In this paper we review the physical and clinical basis for ultrasonic tissue characterization, describe several characterization schemes currently being explored, and attempt to assess the importance such techniques may play in the future of diagnostic medicine.

Walking-gate ultrasonic flaw detector

Abstract: A microprocessor-based ultrasonic inspection system reliably detects fatigue cracks smaller than 0.030 inch under installed fasteners by means of a unique signal-processing method. The signal-processing used in this invention takes advantage of the fact that crack signals "walk" in time as a transducer moves around a fastener. Bolt size, scan depth, and angle of incidence of an ultrasonic shear wave are used to determine the "walk rate" of a defect in the inspection zone. With this geometric information, the signal-processing technique will enhance any pulse-echo return "walking" at the computed walk rate, and thus significantly improve the ratio of crack signal to other signal sources in the material.

Optimum Measurement of Broadband Ultrasonic Data

Abstract: The increasing use of quantitative techniques for characterizing flaws in materials often requires accurate measurement of flaw properties over a wide range of frequencies despite t he presence of noise and despite the variability of the properties of the transducer, electronics, etc. In this paper, we provide a statistical treatment of the problem of extracting the scattering amplitude of a flaw from measured data. A technique is derived for achieving extended bandwidth by combining data from two or more transducers.

Ultrasonic method and apparatus

Abstract: An ultrasonic transducer apparatus and method for examining nuclear reactor jet pump beams for cracking. Examination is conducted in situ. An operator lowers a carriage portion of the apparatus into the reactor vessel with a pole. Ultrasonic signals are transmitted through suitable wiring from an external source to the transducer apparatus, which may employ a pitch-catch or pulse-echo mode of ultrasonic examination to test the beams. The carriage holds oppositely disposed pairs of ultrasonic transducers and positions them suitably near the beam to be examined in a proper orientation thereto. The mode of examination is selected by a switching mechanism. The apparatus includes a signal generator, receiver, and visual display.

Single crystal metal wedges for surface acoustic wave propagation

Abstract: An ultrasonic testing device has been developed to evaluate flaws and inhomogeneities in the near-surface region of a test material. A metal single crystal wedge is used to generate high frequency Rayleigh surface waves in the test material surface by conversion of a slow velocity, bulk acoustic mode in the wedge into a Rayleigh wave at the metal-wedge test material interface. Particular classes of metals have been found to provide the bulk acoustic modes necessary for production of a surface wave with extremely high frequency and angular collimation. The high frequency allows flaws and inhomogeneities to be examined with greater resolution. The high degree of angular collimation for the outgoing ultrasonic beam permits precision angular location of flaws and inhomogeneities in the test material surface.

Transducer carrier for ultrasonic testing

Abstract: A carrier for a plurality of transducers is disclosed. The carrier is useful in ultrasonic testing of furnace tubes. The carrier includes provision for positioning a plurality of transducers against the interior of the tubes.

Multiple wedge element lens for an ultrasonic inspection transducer

Abstract: A plurality of flat or curved, wedge-shaped elements form the surface of aens of an ultrasonic inspection transducer. The multiple wedge-shaped elements permit the ultrasonic energy from the transducer to be focused (1) in a substantially straight line (line focus) parallel to the axis of the lens and (2) deflected from a plane parallel to the wedge-shaped elements and at an oblique angle to the line focus. This achieves a concentration of ultrasonic energy along a line that can be projected into material as shear waves while maintaining equidistance from the transducer's sensing wafer. This results in a concentration of ultrasonic energy that can detect small cracks in a workpiece. Further, with this lens, wider ultrasonic scan may be made with minimal errors in detection. This lens also provides accurate location information on depth of flaws. Furthermore, the novel lens is the only known shape that can achieve reduced errors, wide transducer scan, accurate depth location information and small crack detection of circumferential cracks in tubular shaped products as well as cracks oriented parallel to the direction of scan in flat plates. The same concept can be used on a flat lens (rather than curved cylindrical) with straight multiple wedge elements to minimize errors of flaw detection and identification of flaw location in flat and tubular workpieces while maintaining a wide path of scan.

Ultrasonic test apparatus for tubes and rods

Abstract: An ultrasonic test apparatus for testing tubes or rods by rotating transducers to provide a helical scan, the test transducer, or each of a plurality of transducers, is mounted for adjustable motion along an axis which is inclined by an angle ω with respect to a perpendicular axis intersecting the workpiece surface. The angle ω is selected to provide a desired incident angle α of the ultrasonic energy upon the workpiece surface, whereby to cause a refracted angle β of the ultrasonic energy. Within the range of measuring accuracy for small angles it can be assumed that angle ω approximates angle α.

Ultrasonic and Acoustic Emission Detection of Fatigue Damage.

Abstract: : The primary purpose of the research was to optimize existing ultrasonic and acoustic emission techniques and to investigate new ones for early detection of fatigue damage in aluminum alloys used in aircraft construction. Ultrasonic attenuation measurements made simultaneously with fatigue tests on aluminum alloy bar, and sheet specimens gave warning of crack formation and imminent fracture much earlier than conventional ultrasonic methods. An ultrasonic pulse-echo system was used during fatigue cycling to record conventional A-scan waveforms as well as to monitor ultrasonic attenuation. In addition, acoustic emission signals were recorded simultaneously with the ultrasonic measurements on each test specimen using two different acoustic emission systems. The correlation of evidence of cumulative fatigue damage and acoustic emission data was approached by the use of long term true-rms averaging of the system output and frequency domain analysis of acoustic emission signals recorded at selected intervals throughout the test. The integrity of the data was verified by independent electronic testing of the instrumentation. Visual and in situ eddy current inspection, and optical and scanning electron microscopy were used to correlate acoustic emission and ultrasonic attenuation data to the physically deformed microstructure.

Rotary ultrasonic testing apparatus

Abstract: A rotary ultrasonic testing apparatus includes an annular stator; an annular rotor mounted on the stator for rotation about a workpiece to be tested as it is moved through the stator and rotor; and an ultrasonic probe assembly mounted for rotation with the rotor, said probe assembly comprising a cranked arm pivotally mounted at the crank thereof upon a bearing pin having an axis parallel to the axis of the rotor, the cranked arm carrying towards one end an adjustable counterweight and at the other end an ultrasonic probe block and guide shoe for facing to the surface of the workpiece, said bearing pin being adjustable in position relative to the rotor axis, spring means for limiting movement of the arm about the bearing pin, and water supply means connected to the probe pad.

Ultrasonic assessment of cumulative internal damage in filled polymers (II)

Abstract: An ultrasonic technique previously developed for studying dewetting and cumulative internal damage in filled polymers, such as solid rocket propellents, has been improved. The previous theoretical treatment is here expanded to include internal vacuoles of general spheroidal (rather than spherical) shape. Experimental measurements of sound speed and attenuation in a solid propellant material are utilized together with the modified theoretical model to calculate the internal damage parameters of effective vacuole size and number density as functions of applied uniaxial tensile strain. Results obtained from the model near the point of material failure are in excellent agreement with those provided by independent microscopic observations made on several rupture surfaces of propellant samples stressed to failure.

12. Further Mechanical Techniques

Abstract: Publisher Summary This chapter discusses the relation of ultrasonic properties to molecular structure. The structural information about polymers is examined, and the amplitude of the ultrasonic waves used is restricted to values small enough that no permanent changes are brought about in the polymer. In the immersion technique, the specimen, transmitting transducer, and receiving transducer are all immersed in a liquid. Ultrasonic pulses are sent from one transducer to the other, both with and without the specimen in the path of the sound beam. It is found that from the changes in the detected signal observed when the specimen is removed, the speed and absorption can be obtained. Shear speed is measured by rotating the transducers so that the sound beam strikes the specimen at an angle. Longitudinal and shear measurements are made separately with different sets of transducers for each mode. Quartz transducers are often used because it is relatively easy to excite these crystals into harmonics of their resonant frequency, thus giving a range of measurement frequencies from the same transducers.

Ultrasonic testing of sheet and plate stock

Abstract: Sheet or plate stock is used as to defects by a row of ultrasonic transmitting transducers on one side and receiving transducers on the other. The transmitting transducers receive frequency-modulated signals via individual buffers, and the receiving transducers feed individual, digital amplitude envelope minima to detection circuits whose outputs are fed to a computer which also feeds operating parameters to the source for the modulated signals. Different types (autonomy) of the receiver channels are described as well as diagnostic and setup procedures.

Manufacture and inspection of an article

Abstract: Some turbine blades are produced by casting, using the lost wax process. The blades may include cooling air passages and the wall thickness of these is tested ultrasonically i.e. by transmitting and receiving acoustic pulses from and to, a common transducer. Lately the blades, having been cast, are directionally solidified. This process changes the grain structure such that during inspection, pulses received by the blade, have been dissipated. The invention provides ultrasonic testing ability by using a unidirectional pulse transmission system, resulting in pulses which, having passed outwards through the passage wall, still have sufficient energy to effect an indication of wall thickness.

Stress Measurement and Bolt Tensioning by Ultrasonic Methods

Abstract: In the past decade, a new technique has been developed for measuring tensile stresses in solids This ultrasonic technique has been used thus far primarily for measuring fastener tension The precision of measurement is routinely to 2–3% and, with special care, to ∼1% The method is insensitive to the frictional losses which plague tensioning by torque wrench Though the approach is relatively new, it promises a wide range of applicability

Ultrasonic imaging using trapped energy mode Fresnel lens transducers

Abstract: A focusing transducer utilizing trapped energy modes can be easily fabricated by plating a number of concentric rings of electrodes on a suitable piezoelectric plate of uniform thickness. The concentric ring structure acts as a Fresnel lens and can be used to obtain excellent lateral focusing of ultrasonic waves. Several transducers operating in the 2–5 MHz range have been produced using PZT-7A as the piezoelectric material. The near field radiation pattern has been observed directly in front of the plate using the first order diffraction peak from a laser probe. It is confirmed that there is good acoustic isolation between the rings and that they radiate in the trapped energy mode. The ultrasonic radiation pattern of the Fresnel lens has been observed at various distances from the plate and compared with computed results which show excellent agreement. Furthermore, the axial diffraction pattern of the lens can be optimized by adjusting ring spacings. During the course of this study a new, previously unreported mode of energy trapping has been discovered. The explanation for this method of trapping is briefly discussed. Finally an acoustic through-transmission imaging system incorporating one focusing transducer is used for imaging of flaws in composite materials.

Ultrasonic inspection of hot thick steel products

Abstract: A system has been developed for the ultrasonic inspection of hot thick steel products. The system uses a special type of longitudinal-wave transducer with separate transmitter and receiver, which is armoured and thermally protected. A periodic, dry pressure coupling system is used. The system has been used on metal thicknesses of up to 600 mm and temperatures of up to 1200°C at inspection frequencies of 0.5 MHz and 1 MHz. The results show that the system is sufficiently sensitive at high temperatures to detect a 5 mm diameter artificial defect at a depth of 500 mm with two backwall echoes.