Showing papers in "Nondestructive Testing and Evaluation in 1987"
TL;DR: In this article, surface cracks on sintered SiCMOR bars are ultrasonically measured by a dB drop technique, using surface acoustic waves, and the magnitudes of two error components in the ultrasonic measurement are evaluated: a random component due primarily to the finite beam width, and a consistent error component, due closure effects at the crack tip.
Abstract: Surface cracks on sintered SiCMOR bars are ultrasonically measured by a dB drop technique, using surface acoustic waves. These values of crack size are compared with those obtained by applying linear elastic fracture mechanics to destructive measurements of bar strength. The magnitudes of two error components in the ultrasonic measurement are evaluated: a random component, due primarily to the finite beam width, and a consistent error component, due to closure effects at the crack tip.
17 citations
TL;DR: The Cylindrically Guided Wave Technique (CGWT) as discussed by the authors makes intelligent use of the mode-converted signals, or trailing pulses, to detect corrosion wastages in cylindrical objects.
Abstract: Elastic wave propagation in a bounded medium significantly differs from that in an unbounded medium. The bounded medium in the form of a cylinder acts like a solid waveguide directing the wave with its geometry. A continuous or a pulsed wave interacts with cylindrical boundaries producing mode-converted signals in addition to the backwall echo. The signals are received at constant time Intervals directly proportional to the diameter of a solid cylindrical object such as a bolt or an anchor stud. The Cylindrically Guided Wave Technique (CGWT) makes intelligent use of the mode-converted signals, or trailing pulses, to detect corrosion wastages in cylindrical objects.
3 citations
TL;DR: In this paper, a forward Compton scatter gamma-ray imaging device is described and the gamma ray absorption in mild-steel samples containing voids is discussed, and it is shown that any corrections for absorption invariably produces artifacts in the images of regions around voids, although this phenomenon is less significant for smaller voids and less dense materials.
Abstract: A forward Compton scatter gamma-ray imaging device is briefly described and the gamma-ray absorption in mild-steel samples containing voids is discussed. It is shown that in general any corrections for absorption invariably produces artifacts in the images of regions around voids, although this phenomenon is less significant for smaller voids and less dense materials
3 citations
TL;DR: In this article, the eddy-current touch method of crack detection can size cracks from the changes in the characteristics of the lift-off curves of mild steel samples, which can be used for testing of welds.
Abstract: The eddy-current touch method of crack detection can size cracks from the changes in the characteristics of the lift-off curves. Results obtained for mild steel samples show accuracies better than those obtained with the ACPD method for crack depths of 5 mm and less. For materials, such as different types of steels, having not very dissimilar properties, a calibration block for one type can be used for another. This is advantageous with the testing of welds
3 citations
TL;DR: In this article, non metallic inclusions in steel were extracted by means of an organic compounds film, type epoxy, and the inclusions were then extracted and the microstructure copied.
Abstract: Non metallic inclusions in steel were extracted by means of an organic compounds film, type epoxy. The analyzed- steel surface was previously etched with Br/CH3OH solution, so that the inclusions were in relief, then it was covered by an organic film. The inclusions were then extracted and the microstructure copied. They were then observed through optical microscopy and scanning electron microscopy. The conductivity of the sample was obtained by a metallic deposit on the inclusions and the phases that comprise it were studied by energy dispersive analysis X Rays(EDAX) associated to SEM. The same formalism as the one used for thin foil was applied. Evaluations of comparative benefits were carried out regarding precision and speed compared to other nondestructive and destructive techniques common in the characterization of inclusions in steel
2 citations
2 citations
TL;DR: In this article, the AE wave emitted from nucleating of microcracks or breaking of inclusions was detected by six transducers mounted on the specimen, then amplified and digitized by a highly efficient wave memory.
Abstract: AE wave emitted from nucleating of microcracks or breaking of inclusions was detected by six transducers mounted on the specimen, then amplified and digitized by a highly efficient wave memory. And three dimensional location was carried out on various materials, that is, 3 types of Ti alloys, A533B steel, A470 steel. The difference in the tendency of microcrackings formation in different fracture mode or microstructure was confirmed.
2 citations
TL;DR: A novel microcomputer-controlled multifrequency eddy current tester permitting the optimal frequency combination to be automatically determined for a given testing application is presented.
Abstract: This paper presents a novel microcomputer-controlled multifrequency eddy current tester permitting the optimal frequency combination to be automatically determined for a given testing application. Measuring signals are digitized at the earliest possible time which is an essential criterion for flexible evaluation algorithms.
1 citations
TL;DR: In this paper, a method which employs both longitudinal wave and mode-converted shear wave scattered from a flaw is used to reconstruct the image of the flaw and some experimental data has been collected on a circular cylinder.
Abstract: A method which employs both longitudinal wave and mode-converted shear wave scattered from a flaw is used to reconstruct the image of the flaw. Some experimental data has been collected on a circular cylinder.
1 citations
1 citations
TL;DR: In this paper, a new method of monitoring the cure of resins in paper laminates is described, where samples of high pressure decorative phenolic laminate with degrees of cure ranging from 75 to 100 percent are scanned with 3 cm microwaves.
Abstract: A new method of monitoring the cure of resins in paper laminates is described. Samples of high pressure decorative phenolic laminates, with degrees of cure ranging from 75 to 100 per cent, have been scanned with 3 cm microwaves. It has been shown that the amplitude of through-transmitted waves decreases linearly with increasing cure, the correlation being such that the degree of cure of a given sample should be obtainable virtually instantaneously to a standard deviation of ± 2 per cent.
TL;DR: In this paper, a three-ellipsoid intersection method is formulated to locate a defect inside a piece of metal in 3D space, and a defect detection algorithm is presented.
Abstract: A three-ellipsoid intersection method is formulated to locate a defect inside a piece of metal in three-dimensional space