Showing papers in "Non-destructive Testing in 1974"
TL;DR: The ASME Boiler and Pressure Vessel Code (BPV Code) as discussed by the authors is the most widely used boiler and pressure vessel code in the world and has been adopted as by-laws in most states.
Abstract: As codes of practice are often the starting point for ndt, the journal covers some of the important codes and their implications from time to time. This paper gives a European view of a major American code. The implications to ndt will be discussed later. The technical rules for the design and construction of steam boilers and pressure vessels in the USA are found in the ASME Boiler and Pressure Vessel Code (BPV Code). In most states the rules of the BPV Code have been adopted as by-laws. The authors review of the history, contents and application of the code. They also give details of the application of the code by manufacturers outside North America and briefly compare the equivalent German boiler and pressure vessel standards.
83 citations
TL;DR: In this article, the significance and measurement of the frequency and shape of acoustic emissions are discussed and the implications of this understanding of the nature of acoustic emission and illustrates these implications by a description of a programme of investigation at AERE Harwell.
Abstract: The author discusses the significance and measurement of the frequency and shape of acoustic emissions. He considers theoretical descriptions of acoustic emission and compares them with experimental evidence. He considers the implications of this understanding of the nature of acoustic emission and illustrates these implications by a description of a programme of investigation at AERE Harwell. This programme added to our knowledge of acoustic emission and the author considers the results in the light of other experiments. He concludes that spectral analysis could complement the use of amplitude distribution and ring-down counting but not enough is yet known of the general meaning of the spectrum of an acoustic emission.
24 citations
TL;DR: The eddy-current method is widely used for the non-destructive testing of tubes as discussed by the authors, and it has been used extensively in the last few decades for nuclear engineering applications.
Abstract: The eddy-current method is widely used for the non-destructive testing of tubes.1 This report describes the extensive progress achieved in the last few years. The author discusses examples of testing techniques for tubes for nuclear engineering where extreme sensitivity is of the utmost importance, although the principles are also applicable to all types of tubes.
17 citations
TL;DR: In this article, the authors present representative examples drawn from the literature of such applications, and draw comparison with conventional non-destructive testing techniques in some cases, concluding that acoustic emission can provide information that is difficult or impossible to obtain by other techniques, and can therefore cut costs substantially in the quality assurance of a wide variety of industrial products.
Abstract: This final paper in the series on acoustic emission deals with existing industrial applications of this technology. Such applications have increased greatly in recent years and now include such areas as weld monitoring, monitoring of proof tests on structures and components, and the detection and location of flaws in pressure vessels. The paper presents representative examples drawn from the literature of such applications, and draws comparison with conventional non-destructive testing techniques in some cases. The authors conclude that acoustic emission can provide information that is difficult or impossible to obtain by other techniques, and can therefore cut costs substantially in the quality assurance of a wide variety of industrial products.
17 citations
TL;DR: In this article, an ultrasonic-frequency-spectral analysis method of detecting flaws in advanced composite materials is described, which depends on the phenomenon of resonance interference of acoustical waves in materials.
Abstract: The authors describe an ultrasonic-frequency-spectral analysis method of detecting flaws in advanced composite materials. This non-destructive technique depends on the phenomenon of resonance interference of acoustical waves in materials. When the material thickness is an integral multiple of the half wavelength of the sound waves, destructive interference of a return echo by multiple reflections in the material produces anti-resonant dips in the frequency spectrum for the reflected signal. The period of these dips is related to the material thickness normal to the beam path. Delaminations or voids in a plane perpendicular to the direction of propagation of the sound waves may be observed through their characteristic anti-resonant frequencies. Graphite — epoxy composite specimens containing flat-bottom holes and small planar voids were used as examples of the application of this technique. The authors present analytical development, experimental procedures, and spectral analysis results in this paper.
11 citations
TL;DR: In this paper, the authors argue that the mere detection of voids is not good enough as a method of quality assurance for adhesively bonded joints and instead the aim of ndt must be a direct correlation with the failure property to be predicted.
Abstract: The authors argue that the mere detection of voids is not good enough as a method of quality assurance for adhesively bonded joints. Instead the aim of ndt must be a direct correlation with the failure property to be predicted.
11 citations
TL;DR: In this article, the authors describe a technique of testing adhesively bonded lap joints of a wide range of materials, which is designed to help setting up quality control for manufacture, and believe it can be developed into a cheap, light instrument.
Abstract: This paper is one of a number given at a conference in London in April on ndt of bonded joints. The author describes a technique of testing adhesively bonded lap joints of a wide range of materials. It is designed to help setting up quality control for manufacture. The author believes it can be developed into a cheap, light instrument.
6 citations
TL;DR: In this article, the authors describe the use of the thin layer activation technique in measuring surface loss of materials due to wear and corrosion with particular reference to iron and steels, which is applicable to these materials and composites containing them, eg ceramics and plastics.
Abstract: The author describes the use of the thin layer activation technique in measuring surface loss of materials due to wear and corrosion with particular reference to iron and steels. The active layer is usually between 30 μm and 300 μm thick and the sensitivity of the method is about 0.5 μm. However the potential exists for active layers as small as a few micrometres and as large as about 30 mm to be produced and monitored during the wear process. Activity depth distributions resulting from the irradiation of such common industrial materials as iron, copper, aluminium and carbon by various charged particle beams have been calculated. The technique described is applicable to these materials and composites containing them, eg ceramics and plastics, and to many other elements including silicon and hence glasses enamels and abrasives.
6 citations
TL;DR: In this paper, the production aspects of controlling the manufacture and testing of adhesive-bonded primary aircraft structures are dealt with, while recognising the requirement for in-service testing, the problems encountered are somewhat different and should be treated as a separate issue.
Abstract: This paper deals with the production aspects of controlling the manufacture and testing of adhesive bonded primary aircraft structures. Whilst recognising the requirement for in-service testing, the problems encountered are somewhat different and should be treated as a separate issue.
5 citations
TL;DR: In this article, surface fatigue cracks were induced by tension-tension loading the plates in a three-point bending configuration at a frequency of 28 Hz and under constant load and R-factor.
Abstract: The authors describe investigation on surface fatigue cracks penetrating part of the N ay through flat plates of steel, titanium and aluminium. The cracks were induced by tension-tension loading the plates in a three-point bending configuration at a frequency of 28 Hz and under constant load and R-factor. The metals were D6ac steel heat-treated to 1 447 MN m −2 , annealed Ti-61-4V and 2219-T87 Al. The investigators then found the response of the cracks to ultrasonic shear waves by delta-scan. Elox slots of 1.52 × 0.25 × 0.76 mm length, width and depth served throughout the experiments as reference reflectors. The investigators found that stress relieving affected the ultrasonic response as did tension, cyclic compression and time. In fact, the ultrasonic echo in the aluminium and titanium was greater after many cycles of small compression or few cycles of great compression. But steel gave no such result. Tension increased the ultrasonic response to a degree related to the load. The echo lessened with time, however, because of creep.
4 citations
TL;DR: In this paper, the authors summarized studies which go some way towards a solution to some of these problems: determinations of fibre type, volume fraction, alignment of a laminate and porosity in the matrix.
Abstract: New problems in quality control have arisen from the current widespread use of cfrp. In this article the author summarizes studies which go some way towards a solution to some of these problems: determinations of fibre type, volume fraction, alignment of a laminate and porosity in the matrix. It was found that velocity measurement gave much information on these properties.
TL;DR: In this article, the authors describe methods and equipment available for detecting defects in tubes by the leakage-flux method and the second part of the article will cover eddy-current techniques.
Abstract: The wide variety of electromagnetic testing systems for tubes has been developed because of the multitude of materials, manufacturing methods and defects encountered in the tubemaking industry. The author describes methods and equipment available for detecting defects in tubes by the leakage-flux method. The second part of the article will cover eddy-current techniques.
TL;DR: In this paper, the authors describe a second statistical analysis of the variations in the properties of ultrasonic probes and show that the probability of a probe giving a malfunction is 53% for lower frequency probes compared with 76% for higher frequency probes.
Abstract: The authors describe a second statistical analysis of the variations in the properties of ultrasonic probes. The probes evaluated for customers on the NDT Centre's probe-beam plotter provided the sample. Defining, as before, limits of acceptability in those parameters subject to changes in particular applications, it appears that the probability of a probe giving a malfunction is 53% for lower frequency probes compared with 76% for higher frequency probes. These figures compare with earlier estimates, based on the same limits of acceptability, of 45% and 81% respectively.
TL;DR: Preliminary results demonstrating the feasibility of stroboscopic neutron radiography are presented and a technique using multiple cadmium filters has been developed to improve contrast in radiographs of hydrogenous objects.
Abstract: The authors have investigated thermal and epithermal neutron radiography using a 35 MeV pulsed electron Linac with emphasis on image resolution. A technique using multiple cadmium filters has been developed to improve contrast in radiographs of hydrogenous objects. The authors present preliminary results demonstrating the feasibility of stroboscopic neutron radiography.
TL;DR: In this article, a system for the detection and processing of acoustic emission was proposed for carbon-fibre reinforced plastics and the range of the emissions detected is 70-1000 kHz.
Abstract: The authors describe a system for the detection and processing of acoustic emission. The system was designed principally for carbon-fibre reinforced plastics. The range of the emissions detected is 70–1000 kHz.
TL;DR: In this paper, the relative effects of uniaxial stress and grain orientation on the Rayleigh-wave velocity in aluminium were investigated and a linear relationship between velocity and grain orientations was established.
Abstract: The author describes an investigation of the relative effects of uniaxial stress and preferred grain orientation on the Rayleigh-wave velocity in aluminium. The calculation of the relationship between Rayleigh-wave velocity and stress is based on second-order elasticity theory. He postulates a linear relationship between velocity and grain orientation. He concludes that changes in velocity due to uniaxial stress in the elastic range and preferred grain orientation are of the same order of magnitude. He reviews some experimental data and compares it with theoretical calculations.
TL;DR: In this paper, it is possible to carry out periodic inspections of reactor pressure vessels in service by the use of remote-controlled ultrasonic testing equipment and modern data logging and processing.
Abstract: It is possible to carry out periodic inspections of reactor pressure vessels in service by the use of remote-controlled ultrasonic testing equipment and modern data logging and processing. Further development is necessary to meet all requirements and to overcome existing problems.
TL;DR: In this paper, a method of infiltrating surface defects with adhesive liquids was described, and high amplitude acoustic emissions were obtained from cracking of the adhesive when the defect opens under load.
Abstract: The author describes a method of infiltrating surface defects with adhesive liquids. After curing, high amplitude acoustic emissions are obtained from cracking of the adhesive when the defect opens under load. Thus the defects can be found.
TL;DR: In this article, the authors used electrical models and made the assumption that differential permeability is responsible for magnetic flux distribution, and selected three types of defect called reference defects from about 80 models of defects in various materials.
Abstract: The rules for the selection of magnetic field strength in magnetic-particle testing are generally based on experience. However, the magnetic properties of steels tested by this method are such that the same value of field strength can give a different magnetic induction. 1 A field strength of 2.4 kA m "l , for example will give a magnetic induction of 1.3 T in Cr steels but 0.02-0.6 T in other steels. Using electrical models and making the assumption that differential permeability is responsible for magnetic flux distribution the authors selected three types of defect called reference defects from about 80 models of defects in various materials. These defects measure 25 x 25, 10 x I00 and 25 x 250/am. The calculations showed that the mean value of differential permeability, for which the three types of reference defects can be detected is 55,130 and 200 respectively.
TL;DR: In this paper, the authors compared automatic inspection methods with human inspection following electromagnetic, neutron or ultrasonic examination of components and illustrated them in terms of the operation of a TV camera.
Abstract: The author contrasts automatic inspection methods with human inspection following electromagnetic, neutron or ultrasonic examination of components. He considers the temporal, spatial and intensity characteristics involved and illustrates them in terms of the operation of a tv camera. He considers some typical examples of instances where automatic inspection is superior and discusses a few of the methods employed in feature analysis in general terms.
TL;DR: In this paper, a remote-control ultrasonic inspection system was used at Oskarshamm unit 1 to ensure safety and to avoid loss of generating time in the nuclear power-generation industry in Sweden.
Abstract: This article explains part of the Swedish programme of studies to ensure safety and to avoid loss of generating time in the nuclear power-generation industry in Sweden. It describes a remote-control ultrasonic inspection system used at Oskarshamm unit 1. The system has been since used at other Swedish reactors.
TL;DR: A technique based on the attenuation of gamma-rays has been developed successfully for the automatic continuous measurement of density changes as discussed by the authors, which was originally designed as a new instrument for use in thermal analysis but other applications are envisaged.
Abstract: A technique based on the attenuation of gamma-rays has been developed successfully for the automatic continuous measurement of density changes. It was originally designed as a new instrument for use in thermal analysis but other applications are envisaged. Chemical changes, if occuring, can be ignored by choosing certain gamma-ray emitting radioisotopes. The authors describe an example of the use of the technique in which the thermal decomposition of a solid hydrocarbon is studied. The advantages of the technique are described.
TL;DR: In this paper, a simple ndt method based on the well known ultrasonic resonance technique was proposed to detect the presence of non-bonds and their depth locations in multi-layered structures.
Abstract: In some types of multi-layered structure it is important to detect not only the presence of non-bonds but also to determine their depth locations. This paper describes a simple ndt method, designed especially to meet this requirement, based on the well known ultrasonic resonance technique.