Showing papers on "Ultrasonic testing published in 1976"

On Inspection of Thin-Walled Tubes for Transverse and Longitudinal Flaws by Guided Ultrasonic Waves

Abstract: REFERENCES [ l ] A. Korpel, L. W. Kessler, and P. R. Palermo, “An Acoustic Microscope Operating at 100 MHz,” Nature, 232,110-1 11 (1971). [ 21 L. W. Kessler, A. Korpel, and P. R. Palermo, “Simultaneous Acoustic and Optical M~croscopy of Biological Specimens,” Nature 239, 111-112, 1972 (Sept. 8). [ 31 L. W. Kessler, P. R. Palermo, and A. Korpel, “Practical High Resolution Acoustic Microscopy,” Acoustical Holography, Vol. 4, Plenum Press, New York (1972), G. Wade, Ed., pp. 51-71. [4] R. Adler, A. Korpel, and P. Desmares, “An Instrument for Making Surface Waves Visible,” IEEE Trans. Sonia and Ultrasonics, SU-15,157-161 (1968). [S] L. W. Kessler, “A Review of Progress and Applications in Acoustic Microscopy,” (A) J. Acoust. Soc. Amer., 53, 246, 1973, Manuscript version J. Acoust. Soc. Amer., May 1974. [6] L. W. Kessler, P. R. Palermo, and A. Korpel, “Recent Developments with the Scanning Laser Acoustic Microscope,” in Acoustic Holography, Vol. 5, P. Green, Ed., Plenum Press, New York (1 974). [7] L. W. Kessler, “Acoustic Microscopy-A New Dimension in Ultrasonic Visualization,” in Proc. of Ultrasonics International 1973 (London), March 1973, p. 173, IPC Science and Technology Press Ltd., London (1973).

The determination of crack penetration using ultrasonic surface waves

Abstract: A theoretical discussion of the use of ultrasonic surface waves for detecting and evaluating surface opening defects in materials is presented. It is suggested that such techniques should not be confined to laboratory use, being well-suited to testing structures with awkward geometries. Experimental data have been obtained to determine the accuracy of the technique.

Ultrasonic inspection of pipelines

Abstract: A method and device which are suitable for the in-place inspection of pipelines are provided. A completely self-contained, mobile inspection station is placed inside a pipeline. The station runs through the pipe and transmits Lamb waves within the pipe wall, receives reflected and transmitted portions of the waves, and records the amplitude and phase of the received waves. The recorded information is analyzed to determine the location and nature of discontinuities in the pipe.

Ultrasonic inspection of austenitic welds

Abstract: Optical and X-ray metallography combined with ultrasonic testing by compression waves was used for inspection of stainless steel weld metal produced by three different welding techniques. X-ray diffraction showed that each weld possessed a characteristic fibre textured structure which was shown by optical microscopy to be parallel to columnar grain boundaries. Metallographic evidence suggested that the development of fibre texture is due to the mechanism of competitive growth. From observations made as a result of optical metallographic examination the orientation of the fibre axis could be predicted if the weld geometry and welding procedure were known. Ultrasonic velocity and attenuation measurements as a continuous function of grain orientation, made on cylinders machined from weld samples, showed that attenuation was strongly orientation dependent. It was concluded that the sensitivity of ultrasonic inspection to small defects is unlikely to be as high for austenitic welds as for ferritic even when transmission is improved by modifying the welding procedure to improve the ultrasonic transmission.

Length mode piezoelectric ultrasonic transducer for inspection of solid objects

Abstract: The transducer is constructed from individual transducer elements arranged in an array and configured to exhibit a predominant, longitudinal mode transversely to the array. The elements are interconnected through thin flexible sheets. Each element is individually damped, and the transducer as a whole is electrically damped through resonance with the clamped capacitance and dissipation. Electrical control permits in-phase operation of all transducer elements or control with preselected phase differences.

Ultrasonic waves: their interferometric measurement and display.

Abstract: A system for the measurement and visualization of small displacements has been developed that features high sensitivity and acoustic-wavelength-limited resolution over apertures as large as 15 cm at frequencies up to 10 MHz. Acoustic-wave displacement amplitudes as small as 0.07 A are measured by interferometrically detecting the motion of a thin, acoustically transparent, metallized pellicle as the ultrasonic wave passes through it. The system can also be adapted to measure and display any small vibratory motion. The basic arrangement is that of the Michelson interferometer with the addition of an open-loop method to stabilize the response and a deflection system in one leg of the interferometer to scan the pellicle. Presently, the system is used in the study of the interactions of ultrasonic waves with biologic tissue and the observation and measurement of radiation patterns of acoustic transducers.

Method and apparatus for monitoring the operation of ultrasonic testing of tubes and bars

Abstract: This invention relates to immersion ultrasonic pulse-echo testing of tubes or bars for internal defects wherein means are provided to continuously monitor the operation of the test channel. As ultrasonic energy enters the workpiece, the round workpiece surface causes acoustic energy scatter responsive echo signals which are sensed by the transmitter probe, are amplified and applied to a threshold circuit. If the amplitude of the scatter responsive signal falls below a predetermined level, an output signal indicative of "loss of operation" is produced. Means are provided to inhibit such output signal in the event of only a momentary decrease of the scatter responsive signal below a predetermined value.

Ultrasonic inspection of materials with coarse grain anisotropic structures

Abstract: During the ultrasonic testing of course-grained anisotropic materials, structural noise due to scattering of ultrasound by inhomogeneities can be produced which may interfere with the detection of flaws in the material. This paper reviews the theoretical determination of structural noise and details some of the methods developed to increase the signal-to-noise ratio in ultrasonic testing of course-grained material. Although the problem of structural noise has not been completely overcome, it is suggested that the methods described here represent a significant advance towards its solution.

Ultrasonic testing device and method

Abstract: This invention relates to an apparatus and method for non-destructive ultrasonic testing, such as flaw detection and thickness measurement, of elongated bodies, such as pipes and rods or coatings thereon. Ultrasonic signals are sent and received by transducers held in a rotating member while being substantially submersed in an acoustically transmitting liquid such as water. The rotating member is supported by bearings which are resistant to the transmitting liquid.

Ultrasonic sound source and method for manufacturing rectangular diaphragm of ultrasonic sound source

Abstract: The present invention is directed to an ultrasonic sound source made up of diaphragms composed of rectangular plates adapted, in dimensions, to vibrate in a stripes mode, and mounted, in spaced relation and in multiple stages, on a longitudinal resonance rod which is connected to the horn of the vibrator to produce the ultrasonic waves above the audio-frequency. Thus, an intense ultrasonic sound source which is free from noises and is superior in radiation efficiency is provided.

Ultrasonic probe system for the bore-side inspection of tubes and welds therein

Abstract: A probe system is provided for the bore-side inspection of tube-to-header welds and the like for small diameter tubes. The probe head of the system includes an ultrasonic transmitter-receiver transducer, a separate ultrasonic receiver, a reflector associated with the transducer to properly orient the ultrasonic signal with respect to a tube wall, a baffle to isolate the receiver from the transducer, and means for maintaining the probe head against the tube wall under investigation. Since the probe head must rotate to inspect along a helical path, special ultrasonic signal connections are employed. Through the use of the probe, flaws at either the inner or outer surfaces may be detected.

Ultrasonic weld inspection system

Abstract: An ultrasonic weld inspection system has an ultrasonic transmitting transducer and an ultrasonic receiving transducer on the same side of the weld. A beam of ultrasonic energy from the transmitting transducer directed into the weld center impinges upon a flaw and the receiving transducer is aligned to receive only a portion of the ultrasonic energy beam scattered by the flaw while avoiding receiving reflections of the beam off the flaw and off weld contour irregularities.

Ultrasonic testing method and apparatus for resistance welding

Abstract: An ultrasonic vibrator disposed on one of two opposed electrodes having two metallic plates sandwiched between them for being welded intermittently delivers a pulse-shaped ultrasonic wave to a reflecting surface located in the other electrode and receives the wave reflected from the reflecting surface. The vibrator converts the received wave to an electrical signal that is applied to a minimum sensor and a peak sensor. The minimum sensor senses and holds the minimum peak magnitude of the signal which is then subtracted from the peak magnitude of a similar signal developed within the peak sensor at the time of termination of the welding current. The resulting difference between the two magnitudes determines the weld condition of the welded plates.

Ultrasonic scanner system for cast explosive billets

Abstract: An apparatus for ultrasonic inspection of polyethylene-jacketed, cast expive billets including an immersion tank and a roller system for axially rotating the billet while immersed in the coupling fluid. A drive mechanism traverses a pair of laterally opposed transducers axially of the rotating billet for through-transmission inspection of the majority of the billet. A second drive mechanism sweeps a third transducer through a 90° arc for pulse-echo inspection of the hemispherical base of the billet.

Attenuator circuit ultrasonic testing

Abstract: A broad bandwidth, constant input impedance programmable attenuator circuit for use in pulse-echo ultrasonic testing is provided for attenuating an acoustic discontinuity responsive electrical signal. The attenuator circuit is programmable either by computer or manually and comprises solid state components, specifically a constant current source and unidirectional current conducting devices. The attenuator circuit exhibits both constant input impedance over a wide range of operating frequencies and immunity from varying output load conditions.

Ultrasonic test head carriage for duct and penetration welds - has hoop track and axially movable arm for test heads

Abstract: A testing system support for ultrasonic testing of the external regions of nuclear reactor ducts, pressure vessels, penetration welds and the like comprises a peripheral track, on which a moving trolley can travel circumferentially around the duct and weld This trolley carries a slide, on which a drag lever is pivotally mounted about an axis, the free end of this drag lever carrying the ultrasonic test head or heads The drag lever has its lever arm coupled to the slide by a pivotal drive, esp a pneumatic piston-cylinder drive system The ultrasonic test heads can be moved both radially and axially to enable complicated test paths to be followed without moving the circumferential track carrying the equipment

Comparative ultrasonic response of machined slots and fatigue cracks in 7075 aluminum

Abstract: To assess the suitability of machined flaws as standards for ultrasonic inspection for fatigue cracks, reference blocks were developed for quantitative comparison of pulse echo amplitudes produced by machined flaws and true fatigue cracks of corresponding size and configuration. Flaw shapes investigated were rectnagular, triangular, and half penny, representing the most commonly encountered fatigue crack configurations. For each shape, electric discharge machined (EDM) and saw slits were produced; actual fatigue cracks were grown in low cycle (less than 10 to the 4th power) and in high cycle (greater than 10 to the 5th power) conditions. Ultrasonic parameters investigated were frequency, bandwidth and wave mode. The ultrasonic signals produced by low cycle fatigue cracks averaged 5 dB stronger than those from high cycle cracks of corresponding size and configuration. Depending on flaw and transducer characteristics, a receiver referenced to machined flaws required added gain of 10 to 34 dB for reliable detection of the corresponding true fatigue cracks. Narrow band pulser/receivers and transducers produced the stronger signals, but the broad band equipment produced the larger flaw signal-to-background noise ratio.

Experiments with two types of electromagnetic ultrasonic transducers

Abstract: Two types of electromagnetic ultrasonic transducers were made and tested on mild steel, stainless steel, and aluminum. One of the transducers generates and detects a relatively large amount of longitudinal wave and simultaneously a small amount of radially polarized transverse wave in nonmagnetic metal. The other is for a large amount of radially polarized transverse wave and a small amount of longitudinal wave, also in nonmagnetic metal. Both transducers showed different characteristics for ferromagnetic metal, giving greater efficiency to the radially polarized transverse wave. It was also shown experimentally with an electromagnetic transducer that the mode conversion between longitudinal waves and radially polarized transverse waves occurs fairly efficiently at a vertical reflection.Subject Classification: [43]35.60, [43]35.80; [43]85.40, [43]85.48.

Defective nuclear reactor fuel rod localiser - has deflecting springs with strain gauges on fingers with ultrasonic test heads

Abstract: Defective fuel rods within fuel elements of water-cooled nuclear reactors are localised by introducing a frame with comb-like fingers which have ultrasonic test heads at the free ends. Deflecting springs with srain gauges are attached to the sizes of the free finger ends. Their distance is at least equal to the normal gap between the fuel rods. A processor compares the deflection with the normal value. This device can be used to localised in the one operation both rods with an influx of water and rods which reveal any deformation.

Characterization of Nde Transducers and Scattering Surfaces Using Phase and Amplitude Measurements of Ultrasonic Field Patterns

Abstract: The characterization of transducers for quantative NDE applications requires that the radiation pattern, conversion efficiency, and bandwidth be accurately determined. These quantities may, in principle, be determined if the transducer’s construction and constituent parts are independentiy known. However, most often the internal detai ls of the transducer are unknown and subject to statistical variations and aging. A measurement technique and system for characterizing transducers based upon external measurements is described, which does not rely upon knowledge of the transducer’s construction. Manuscript received April 19, 1976. This work was supported in p a t by the Center for Advanced NDE, operated by the Science Center, Rockwell International, for the Advanced Research Projects Agency and the Air Force Materials Laboratory under Contract F33615-74C-5180. The authors are with the Electronic Sciences Laboratory, University of Southern California, Los Angeles, CA 90007. T

Future Growth of Nondestructive Evaluation

Abstract: Abstmcr-The business of nondestructive evaluation (NDE) will expand in the shortand long-term future because it provides saving? advantages in quality control, materials, energy, manpowa, warranty costs, lawsuits, and the prevention of catastrophic failures. The expansion wiU occur at a faster rate if government funding is available as “wed money” for research and development (R & D) on new methods and equipment. More coordination is needed to translate R & D into novel methods-solutions packages which will benefit the whole economy. Government financing is necessaxy because individual fiis cannot single-handedly afford R & D costs great enough to generate industry-wide benefits. The need for NDE is so great and its potential benefits so large that it could grow even m a contracting economy. When the “limits to growth” me reached, NDE will be indispensable to the equilibrium economy to maximiie resource utilization and keep durable goods operating indefiitely.

Dual trace display for ultrasonic testing apparatus

Abstract: An ultrasonic nondestructive testing system is disclosed which is adapted to display test information representing ultrasonic energy reflected from within an object under test in various modes. In one mode, herein called the set-up mode, a dual display is generated. One of the displays contains a portion of the test information effectively expanded along a horizontal scale, while the other display has a contracted horizontal scale thereby to present essentially all of the test signal. In addition, the other display includes a suitable marker to indicate the location and extent of the test information in the first display. In the other, or test mode, the instrument is adjusted to display only the test information shown in the first display of the set-up mode.

Better detection of large poorly oriented plane defects by ultrasonics

Abstract: Contrary to expectations, the most difficult defects to detect by ultrasonic inspection are large plane defects. This account is far more descriptive than theoretical; it demonstrates that the probability of detecting a poorly oriented plane defect can be increased by using a highly focused ultrasonic transducer at the lowest possible frequency.

Electromagnetic ultrasonic transducer for generating and detecting longitudinal waves /with a small amount of radially polarized transverse wave/

Abstract: An electromagnetic ultrasonic transducer that generates and detects a relatively large amount of longitudinal ultrasonic wave and a small amount of radially polarized transverse ultrasonic wave was built and tested on stainless steel, mild steel, and aluminum at room temperature. The flaw detection ability of the electromagnetic transducer was compared with that of a piezoelectric ceramic transducer, and the signal-to-noise ratios were comparable. It was also shown experimentally with the electromagnetic transducer that mode conversion between a longitudinal wave and a radially polarized transverse wave occurs at the perpendicular incidence.

Digitally controlled ultrasonics for testing steel on line

Abstract: Experience with ultrasonic testing on line has led the British Steel Corporation to consider the use of computers. The authors discuss the factors considered in designing such a system. They describe a modular digitally controlled system developed at BSC. The corporation intend to use it to test plate on line at the Consett Works.

Rotary ultrasonic testing apparatus

Abstract: Rotary ultrasonic testing apparatus comprises an annular stator; a replaceable annular ultrasonic probe assembly mounted for rotation on the stator; and first and second fixed replaceable annular guideways for the articles to be tested, said guideways having internal configurations arranged to conform to the cross-section of the article to be tested and provide a close tolerance guide therefor, and said guideways each having a side surface adjacent the probe assembly which serves at least partially as a radially inwardly extending side wall of the probe assembly.

Testing method using ultrasonic energy

Abstract: A convergent ultrasonic beam is formed by an emitter made as a sphere and directed to a piece under test. Having been reflected from the surface of the piece and from the defect, the ultrasonic beams are separated in space. The ultrasonic beam carrying information on the defect is displayed.