Showing papers in "Non-destructive Testing in 1976"
TL;DR: In this article, a general method of calculating the location of defects in two dimensions from the arrival times at the sensors is presented. But the ACEMAN system, which uses this method can derive the resolution properties of a sensor array in about 7.5 min.
Abstract: Sensors on the surface of a material under stress can detect acoustic emissions from a defect within the material. The difference in time of detection of an emission from the defect at different sensors gives a way of finding where it is. This paper shows a general method of calculating the location of defects in two dimensions from the arrival times at the sensors. The ACEMAN system, which uses this method can derive the resolution properties of a sensor array in about 7.5 min.
260 citations
TL;DR: In this paper, a measuring principle and an instrument based on the analysis of the magnetic noise are presented for the measurement of steel sheet grain size and mechanical properties, the accuracy of the present instrument, and possible other applications in ndt quality control.
Abstract: This paper deals with a new magnetic approach in ndt measurement, namely a measuring principle and an instrument based on the analysis of the magnetic noise. It also gives a short description of the results obtained in this way in the measurement of steel sheet grain size and mechanical properties, the accuracy of the present instrument, and possible other applications in ndt quality control.
36 citations
TL;DR: In this paper, a photoelastic technique was applied to a problem of crack-depth sizing in steel rails by Rayleigh waves, and the visualization of the interactions of ultrasonic waves in notched glass testpieces provided explanations of multiple A-scan received signals.
Abstract: Stroboscopic methods of visualization of ultrasonic waves by schlieren and photoelastic methods have been introduced in recent years. The author describes work which demonstrates the application of the photoelastic technique to a problem of crack-depth sizing in steel rails by Rayleigh waves. The visualization of the interactions of ultrasonic waves in notched glass testpieces provides explanations of multiple A-scan received signals, the origins of which were not previously understood.
24 citations
TL;DR: In this article, the authors describe suitable methods for investigating beam profiles and give details of characteristics of various probe units, quantifying the errors introduced by factors such as surface finish and the location of the specimen within the measurement system.
Abstract: This paper describes suitable methods for investigating beam profiles and gives details of characteristics of various probe units. It quantifies the errors introduced by factors such as surface finish and the location of the specimen within the measurement system. The authors describe how to use a simple stop to produce a narrow parallel beam of high resolution. The paper also compares attenuation readings taken with various probe units, used both in through-transmission and in pulse-echo. It gives some useful correlations. Finally, it investigates methods of calibrating the attenuation readings taken with high resolution systems to give a measure of void content.
19 citations
TL;DR: In this paper, the authors describe experiments to find the degree of magnetization needed to reveal artificial defects with magnetic particles and give an empirical formula to calculate optimum magnetization by coils.
Abstract: This article describes experiments to find the degree of magnetization needed to reveal artificial defects with magnetic particles. The author interprets the results of measurements of tangential magnetic field strength at the surface and the corresponding details of the weld or prepared unwelded edge and the method of magnetization. He recommends practical testing procedures and gives tables for magnetization by prods, yokes and coils. He gives an empirical formula to calculate optimum magnetization by coils.
8 citations
TL;DR: In this article, the authors describe experience with Lamb-wave ultrasonic testing of a rolled hot strip with a robust Sperry-wheel probe on strip at the Port Talbot Works.
Abstract: The authors describe experience with Lamb-wave ultrasonic testing of rolled hot strip. They worked with a robust Sperry-wheel probe on strip at the Port Talbot Works. This strip had an undulating surface with a wavelength of a few metres and an amplitude of 50–300 mm. In spite of this long wavelength, much shorter signal variations were observed.
6 citations
TL;DR: In this article, an evaluation of ndt methods for aluminium-brazed titanium honeycomb structure was carried out and the results indicated that ultrasonic C-scan, eddy-current conductivity testing are needed to evaluate the brazed honeycomb panels for the filleting quality of the basting alloy and for core defects.
Abstract: The author describes an evaluation of ndt methods for aluminium-brazed titanium honeycomb structure. This work is part of a programme of basic research paid for by the National Aeronautics and Space Administration (NASA) towards the development of technology for advanced supersonic transport. The results indicate that ultrasonic C-scan, eddy-current conductivity testing are needed to evaluate the brazed honeycomb panels for the filleting quality of the brazing alloy and for core defects. Eddy-current conductivity was capable of detecting the conversion of the aluminium brazing alloy to titaniium aluminide (TiAl3) at the interface between the face sheet and core.
6 citations
TL;DR: In this article, the authors describe a modular digitally controlled system developed at the British Steel Corporation to test plate on line at the Consett Works and discuss the factors considered in designing such a system.
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.
5 citations
TL;DR: In this paper, the background electronic noise level and the signal-to-noise performance of a typical single channel laboratory acoustic-emission system are analyzed and the results are supported by measurements on a commercial apparatus.
Abstract: The factors controlling the background electronic noise level and the signal-to-noise performance of a typical single channel laboratory acoustic-emission system are analysed and the results are supported by measurements on a commercial apparatus. It is concluded that for such a system the possible improvement in signal-to-noise ratio obtainable by using improved electronics whilst retaining the present type of transducer is limited to dB.
2 citations
2 citations
TL;DR: In this article, the authors describe the principle and practice of a promising technique: magnetic stray-flux testing, which can detect inner and outer flaws in the weld between 5-10% of wall thickness.
Abstract: The world's production of welded tube is rising and needs fast non-destructive testing on the production line to maintain quality efficiently. The author describes the principle and practice of a promising technique: magnetic stray-flux testing. He describes his company's experience with its own system, the Discomat. He describes the current strengths and weaknesses of the technique for this application and concludes that inner and outer flaws in the weld between 5–10% of wall thickness can be detected. However, the technique does not reliably detect cold welding which requires some combined method of testing.
TL;DR: In this paper, the advantages of using established techniques of vibration, or machine health, monitoring to safeguard investment in machinery such as pumps, compressors and fans in industries like refining and petrochemical engineering are discussed.
Abstract: Vibration has long been regarded as an indicator of the condition of rotating machinery and today developments in instrumentation are rapidly turning the mechanic's hunch into an exact science. This paper deals with the application of vibration monitoring to industries employing large numbers of process machines engaged in expensive processes. The author details the advantages of using established techniques of vibration, or machine-health, monitoring to safeguard investment in machinery such as pumps, compressors and fans in industries like refining and petrochemical engineering.
TL;DR: One of Britain's quality inspectorates for military spending, the Aeronautical Quality Assurance Directorate (AQA) is responsible for the quality of equipment and materials for military aviation as discussed by the authors.
Abstract: One of Britain's quality inspectorates for military spending, the Aeronautical Quality Assurance Directorate is responsible for the quality of equipment and materials for military aviation. The directorate has long delegated inspection to approved firms whose inspection system is scrutinized. This system has now developed into contractor assessment where the directorate studies the entire system of quality assurance including management and equipment. Non-destructive testing has been part of the directorate's responsibility since the second world war. The directorate examines and approves specialists and supervises industrial record keeping. Finally, the directorate itself is active in ndt and develops techniques and standards as well as investigating failures.