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Transducer characterization

Description: This report has been prepared specifically for ultrasonic transducer users within the Nondestructive Testing Evaluation (NDE) community of the weapons complex. The purpose of the report is to establish an initial set of uniform procedures for measuring and recording transducer performance data, and to establish a common foundation on which more comprehensive transducer performance evaluations may be added as future transducer performance criteria expands. Transducer parameters and the problems with measuring them are discussed and procedures for measuring transducer performance are recommended with special precautionary notes regarding critical aspects of each measurement. An important consideration regarding the recommended procedures is the cost of implementation. There are two distinct needs for transducer performance characterization in the complex. Production oriented users need a quick, reliable means to check a transducer to ascertain its suitability for continued service. Development groups and the Transducer Center need a comprehensive characterization means to collect adequate data to evaluate theoretical concepts or to build exact replacement transducers. The instrumentation, equipment, and procedures recommended for monitoring production transducers are utilitarian and provide only that information needed to determine transducer condition.
Date: July 2, 1980
Creator: Cross, B. T.; Eoff, J. M.; Schuetz, L. J. & Cunningham, K. R.
Partner: UNT Libraries Government Documents Department
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Magnetic testing probe

Description: A cylindrical eddy current tube testing probe is disclosed. Current flow in dual electromagnetic coils separated by an eddy current sensing coil is so directed that magnetic fields of the electromagnet coils have components extending in opposite directions axially of the tested tube and components extending radially of the tube which add in the region of the eddy current sensing coil.
Date: July 7, 1981
Creator: Scott, G.W. & Chitwood, L.D.
Partner: UNT Libraries Government Documents Department
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04 nuclear safety: pressure piping crack monitoring detection of metal overstress by acoustic emission. Progress report, July-September 1966

Description: The three main areas of effort have been: (1) definition of the general acoustic response pattern related to the gross aspects of forming and extending a crack in various materials, (2) development of a monitor system prototype concept exclusive of transducers and (3) development of a suitable, high temperature transducer. Tests using double cantilever beam (DCB) specimens of various materials to establish conditions of crack formation and growth have indicated that material ductility is a major controlling factor in the acoustic response pattern. It appears to effect both acoustic emission intensity and the point in the crack formation-growth sequence at which the main emission occurs. A concept has been developed for the prototype of a full scale monitor system. Hardware development is being limited to the analyzer portion of the system at this time because it is the part most significant to demonstrating feasibility of the intended application. Signal level and signal rate are both being investigated as possible parameters for evaluating acoustic emission data. Of the various transducers for potential high temperature application, the capacitive or electrostatic transducer now looks most promising. A significant improvement in sensitivity has been achieved and a trial model used during recent tests produced generally satisfactory data. The sequence of effort on the program is being adjusted somewhat from that previously outlined. Some of the more detailed investigative phases will receive only moderate attention, temporarily, in favor of first demonstrating the basic feasibility of detecting acoustic emission and making a meaningful analysis under postulated service conditions.
Date: October 28, 1966
Creator: Hutton, P H
Partner: UNT Libraries Government Documents Department
open access

Studies of ultrasonic beam spread in thick sections

Description: The use of hemispherical holes seems to be a valid procedure for monitoring both forward and lateral beam spread. Provided subsequent data analysis and checks show agreement, this type of reflector would be recommended for Code application. The preliminary evaluation of the 45/sup 0/, 2.25 MHz, 2.54-cm (1-in.) circular transducer case shows consistent results and determines an effective beam width that impacts scanning overlap or index. Additional work should be conducted in order to determine the effects of search unit differences (especially those affecting spectrum, near field, and small changes in the angular orientation). These search unit differences are expected to have even more effect on data for larger angles (e.g., 70/sup 0/). A decided improvement in the determination of the linear parameters such as slope and intercept could be obtained by using a greater number of side-drilled holes and hemispherical reflectors. The increased number of data points should greatly improve the quality of the linear fit and help determine reproducibility of the method.
Date: January 1, 1981
Creator: McClung, R. W.; Cook, K. V. & Latimer, P. J.
Partner: UNT Libraries Government Documents Department
open access

Ultrasonic angle beam profiling in steel using an EMAT receiver

Description: A system for measuring the beam profile of angle beam search units in steel is described. This technique employs an electromagnetic acoustic transducer (EMAT). The EMAT is sensitive to shear waves polarized parallel to the surface and requires no couplant. A steel block with surfaces cut at angles normal to the ultrasonic beam propagation direction is used. The amplitude distribution of the angle beam is measured at the surface of the test block using the EMAT receiver. The information is recorded using a programmable desk top calculator. The calculator then provides a cross sectional beam plot (normal to propagation direction) as well as vertical and horizontal amplitude traces for beam spread measurements.
Date: January 1, 1982
Creator: Becker, F. L. & Busse, L. J.
Partner: UNT Libraries Government Documents Department
open access

Eddy current system for high speed inspection of M-16 cartridge cases

Description: An eddy current system developed to detect cracks, splits, and folds in 5.56 mm cartridge cases at a rate of 1200 cases/minute is described. The system inspects each cartridge case around its entire circumference, and has an operating frequency of 100 kHz which minimizes sensitivity to wall thickness variations. Also discussed is the use of the instrument to monitor cartridge case wall thickness by reducing the operating frequency. At a frequency of 25 kHz, wall thickness can be measured with an accuracy of 0.013 mm (0.0005 in.). Maximum, minimum, and average wall thickness is simultaneously recorded for each case about its circumference at four different locations on the case. Also described are some rather unique features of the electronic instrument. These include an oblong search coil which is contoured to cartridge case motion, a temperature stabilization method based on constant current excitation of send-receive coils, and a rapid automatic nulling technique employing digital methods. Additionally, a method for using a Q-multiplier as either an oscillator or a bandpass filter is described. The method facilitates the use of a bandpass filter that is precisely matched to the eddy current signal generator so that no output phase error occurs during minute drifts in test frequency.
Date: March 1, 1978
Creator: Dilbeck, R. A. & Davis, T. J.
Partner: UNT Libraries Government Documents Department
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Improved eddy current angle probe

Description: Apparatus is described for detecting flaws in a tubular workpiece in a single scan. The coils of a dual coil bobbin eddy current inspection probe are wound at a 45/sup 0/ angle to the transverse axis of the probe, one coil having an angular position about the axis about 90/sup 0/ relative to the angular position of the other coil, and the angle of intersection of the planes containing the coils being about 60/sup 0/.
Date: February 11, 1982
Creator: Nance, R.A.; Hartley, W.H. & Caffarel, A.J.
Partner: UNT Libraries Government Documents Department
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Holographic and acoustic emission evaluation of pressure vessels

Description: Optical holographic interfereometry and acoustic emission monitoring were simultaneously used to evaluate two small, high pressure vessels during pressurization. The techniques provide pressure vessel designers with both quantitative information such as displacement/strain measurements and qualitative information such as flaw detection. The data from the holographic interferograms were analyzed for strain profiles. The acoustic emission signals were monitored for crack growth and vessel quality.
Date: March 5, 1980
Creator: Boyd, D.M.
Partner: UNT Libraries Government Documents Department
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Automatic high-speed process control/quality assurance monitor. [Cartridge cases]

Description: Battelle, Pacific Northwest Laboratories has developed an advanced cartridge case measurement/eject system (CCMES) which automatically inspects and rejects cases up to 1200 per minute. The system consists of a mechanical handler, measurement instruments, and a dedicated computer. System operation is monitored and controlled while the product is being measured. Five case dimensions are measured by an electro-optical system using diode arrays to measure a case image at unity magnification. By scan averaging, measurement standard deviations as small as 2.5 ..mu.. are obtained at a throughput of 1200 cases per minute. Measurements made with the system fall within the uncertainties of hand-gauged values for the same cases. Four zones on each case are examined for surface flaws, such as dents and scratches, by detecting light scattered from the surface. The system can detect these surface flaws at inspection rates of 1200 cases per minute. Using electro-optic methods, two additional measuring stations detect vent hole presence and gross size deviations to prevent mechanical jams. A third station employs an eddy current technique to detect splits and folds in critical regions of the cartridge case. The overall system has passed quality assurance tests administered by the sponsor and will soon be installed at the Lake City Army Ammunition Plant.
Date: January 1, 1978
Creator: Coleman, W J & Swinth, K L
Partner: UNT Libraries Government Documents Department
open access

Feasibility study to assess the use of the four quadrant eddy current test method for inspecting 0.042-inch diameter mild detonator fuse

Description: The objective of the project reported was to assess the four quadrant eddy current test method's sensitivity to wall conditions in a 0.042-inch-diameter mild detonator fuse. Specifically, the wall conditions of interest are core offset, average wall thickness, and cracking and inclusions in the wall. Experiments were performed that provided data indicating that these conditions can be determined by the method. It is also concluded that quantitative information on wall conditions can be obtained as well, provided this is done in correlation with radiographs. (LEW)
Date: March 1, 1986
Creator: Prince, J.M.
Partner: UNT Libraries Government Documents Department
open access

Generalized ultrasonic system for microcomputer controlled data collection

Description: A system developed by the NDE Group of the Los Alamos Scientific Laboratory for the automated scanning of objects with an axis of rotation is described. This system is still being expanded to allow greater versatility in the motions. Data which was collected using the system and some typical test objects are also presented and discussed.
Date: January 1, 1980
Creator: Strong, R. D.
Partner: UNT Libraries Government Documents Department
open access

Scattering by flaws in a slab or a half-space

Description: It is the main function of quantitative NDE to detect and to evaluate defects. Some of the most dangerous defects are cracks, especially cracks on or near surfaces. These cracks can be found by scattering ultrasonic waves from them, but up to now there is no theory (at least in the most interesting low-to-intermediate frequency region) which has been implemented to compute scattering from surface or near-surface cracks in 3d. The purpose of the present report is to explain, via a simple scalar example, the principles of a general boundary-integral-representation method which has been used to calculate scattering of waves of all polarizations by a 2d surface or subsurface crack. The method is developed for bulk defects and cracks in a slab as well as in a half-space, and is straightforwardly applicable to 3-dimensional problems as well as to 2d ones.
Date: January 1, 1982
Creator: Visscher, W.M.
Partner: UNT Libraries Government Documents Department
open access

Effects of microstructure on the speed and attenuation of elastic waves

Description: A unified theory pertaining to the sensitivity of the propagation of an elastic wave to changes in the microstructural details of a material is discussed. In contrast to nearly all previous treatments a first principles approach, using developments from other multiple scattering problems and adapting them to the elastic wave case, is followed. We then present several simple, standard approximations. In the process the validity of the commonly made assumption that ..cap alpha.. = n anti sigma is clarified, and the effective speed, illustrating its complementary character to the attenuation, is computed. The principal objective is to present the formal analysis necessary to treat systematically the dependency of the wave propagation on microstructural statistics.
Date: January 1, 1982
Creator: Gubernatis, J.E. & Domany, E.
Partner: UNT Libraries Government Documents Department
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Application of MOOT to scattering of elastic waves from compound inclusions

Description: It is shown how MOOT (method of optimal truncation, a convergent T-matrix scheme) can be used to calculate elastic wave scattering from compound inclusions, i.e., inclusions which themselves contain flaws - inclusions, voids, or cracks. The general equations are derived, and they are solved for a particular axially-symmetric case - a cracked spherical inclusion immersed in fluid. The crack edge is a circle on the equatorial plane; the crack can extend either inward to the center or outward to the surface of the sphere. Numerical results are given for scattering of acoustic waves from cracked spheres of various materials. Cracked spheres can be fabricated relatively easily, and may be useful in NDE calibrations.
Date: January 1, 1980
Creator: Visscher, W.M.
Partner: UNT Libraries Government Documents Department
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Direct comparison of unloading compliance and potential drop techniques in J-integral testing

Description: Single-specimen J-integral testing is performed commonly with the unloading compliance technique. Use of modern instrumentation techniques and powerful desktop computers have made this technique a standard. However, this testing technique is slow and tedious, with the loading rate fixed at a slow quasi-static rate. For these reasons the dc potential drop technique was investigated for crack length measurement during a J-integral test. For direct comparison, both unloading compliance and potential drop were used simultaneously during a J-integral test. The results showed good agreement between the techniques. However, the potential drop technique showed an offset in crack length due to plastic blunting processes. Taking this offset into account, J/sub Ic/ values calculated by both techniques compared well.
Date: January 1, 1984
Creator: McGowan, J. J. & Nanstad, R. K.
Partner: UNT Libraries Government Documents Department
open access

Experiments in the application of ultrasound diffraction tomography for nondestructive testing

Description: We have designed computer programs to simulate ultrasound projection scans and to reconstruct the tomographic planar image. We have also used the reconstruction algorithm on actual test data and have obtained a crude but promising image. 11 refs., 9 figs.
Date: July 1, 1988
Creator: Azevedo, S. G. & Fitch, J. P.
Partner: UNT Libraries Government Documents Department
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Improved techniques for the ultrasonic characterization of graphite

Description: Near-conventional pulse-echo flaw detection techniques can be successfully applied to graphite material. If the specimen configuration (i.e., length-to-diameter ratio) is conducive to the choice of ultrasonic test parameters dictated by the material screening tests, then only the test sensitivity needs to be established. Conventional test block approaches to calibration work well; however, uniform homogeneity of the specimens to be tested must be assumed (depending on the graphite, this may be an invalid assumption). Sensitivities that we have demonstrated typically detect 0.5- to 0.75-mm (0.020 to 0.030-in.) reflectors at depths up to 102 mm (4 in.) for GRAPHNOL (drilled holes, not flat bottom). Other materials may dictate inspection for much larger discontinuities. The least sensitive tests performed to date (using the storage oscilloscope approach) required flat-bottom holes of 6.35 mm (0.250 in.) in diameter for calibration. This relatively insensitive test was necessary because of the billet length and material characteristics.
Date: January 1, 1981
Creator: Cook, K. V. & Simpson, W. A.
Partner: UNT Libraries Government Documents Department
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Microstructural Effects and Signal-Enhancement Techniques in Ultrasonic Examination of Stainless Steel

Description: Ultrasonic inspection of large-grain stainless steel and stainless steel welds is difficult, and the results obtained are not easily interpreted. In the present study, the effects of stainless steel microstructure on ultrasonic test results are described, and several signal-processing techniques for enhancing ultrasonic flaw signals are discussed.
Date: September 1976
Creator: Kupperman, D. S. & Reimann, K. J.
Partner: UNT Libraries Government Documents Department
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Failure analysis and surety design of composite patching systems.

Description: This work presents an experimental evaluation of patch repair of solid laminated composites. The study was focused on destructive and nondestructive tests of full-scale repaired panels under static tension loading conditions. The testing program consisted of ten panels: three pristine, three damaged, three repaired and one repaired with mismatched fiber orientation patch. The evaluated panels were (300 mm x 675 mm) in size and consisted of 6-ply ((-60 /60/0){sub s}) quasi-isotropic laminates. The destructive tests were performed by North Carolina A&T State University and the nondestructive tests were performed by Iowa State University using Pulse-echo C-scan, Air coupled TTU and Auto-Tap. Sandia National Laboratories validated the NDT tests by implementing NDE field methods. Based on the evaluation performed in this study, it appears that the patch repair is an effective means in retrofitting damaged solid composite laminates.
Date: August 1, 2004
Creator: Hamoush, Sameer (North Carolina A&T State University, Greensboro, NC)
Partner: UNT Libraries Government Documents Department
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Fundamental theory of elastic wave scattering by defects in elastic materials: integral equation methods for application to ultrasonic flaw detection

Description: The use of ultrasonic methods in nondestructive testing depends on the interpretation of the scattering of sound waves by flaws. The theory of elastic waves and their scattering in non-uniform media is developed in detail from first principles, and in generality. Both integral equation and differential methods are discussed, with emphasis on the former. General methods for defining scattering cross sections are presented, and conservation theorems are noted. The Born Approximation to the integral equation is presented, and computed results for several experimental situations are discussed. Several corrections to papers in the literature are made, and in particular the exact scattering of a transverse wave by a spherical flaw is compared with the Rayleigh (long wave) limit.
Date: May 1, 1976
Creator: Gubernatis, J.E.; Domany, E.; Krumhansl, J.A. & Huberman, M.
Partner: UNT Libraries Government Documents Department
open access

Nondestructive testing of 105mm depleted uranium penetrators.

Description: The report is an information update concerning the nondestructive testing (NDT) activities at Pacific Northwest Laboratories (PNL) for depleted uranium penetrator (XM774, XM833) quality inspection and evaluation. This report covers NDT activities from August to November, 1979.
Date: December 1, 1979
Creator: Morris, C. J. & Foreman, S. J.
Partner: UNT Libraries Government Documents Department
open access

Theory and numerical calculation of the acoustic field exerted by eddy-current forces

Description: The equations for calculating the acoustic field produced within a nonmagnetic metal by interaction of eddy currents with a static magnetic field were obtained on the assumptions (1) an ultrasonic wave is generated by the electromagentic force through classical and macroscopic phenomena; (2) the electric, magnetic, and elastic properties of the metal are linear, isotropic, and homogeneous throughout the metal, which occupies semi-infinite space; (3) the whole system is axially symmetric; and (4) eddy currents and elastic waves show a steady-state sinusoidal variation. The acoustic field produced by a specific electromagnetic ultrasonic transducer with axial symmetry was calculated numerically, and the results showed a well-defined ultrasonic wave beam, which was narrower than had been expected from the size of the transducer. (auth)
Date: January 1, 1976
Creator: Kawashima, K.
Partner: UNT Libraries Government Documents Department
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