Showing papers on "Acoustic emission published in 1983"
Journal Article•
TL;DR: In this article, the authors discuss different types of instrumentation and signal analysis techniques used with single channel acoustic emission tests and discuss the general physical principles encountered in the field of acoustic emission.
Abstract: This is a tutorial article. It first covers the general physical principles encountered in the field of acoustic emission. It then discusses different types of instrumentation and signal analysis techniques used with single channel acoustic emission tests.
180 citations
TL;DR: In this article, the angular variation of diffracted signal amplitude when infinite plane P or SV waves are incident on a semi-infinite crack is derived for the case of a defect symmetrically placed with respect to transmitter and receiver.
95 citations
TL;DR: In this article, the thermal cycling behavior of a plasma-sprayed ZrO2-12 wt pct Y2O3 coatings with and without bond coatings of Ni-Cr-Al-Zr was studied.
68 citations
TL;DR: In this paper, the authors demonstrate the discontinuous nature of transgranular stress-corrosion cracking (TGSCC) in brass and to account for it in terms of the dynamics of competing plastic deformation and brittle crack growth.
68 citations
TL;DR: In this paper, a simple model based on frictional sliding of conductor is presented to interpret acoustic data; agreement between theory and experiment is good. But the results show that flux motion, except during flux jumping, produces no discernable acoustic signals.
Abstract: Origins of acoustic emission (AE) in superconducting wires have been investigated. Our experimental results indicate that wire motion is a dominant source of AE in current‐carrying wires, both superconducting and nonsuperconducting. Furthermore, the results show that flux motion, except during flux jumping, produces no discernable acoustic signals. Both of these conclusions differ from the conclusions of earlier AE results which attributed the major source of AE signals in superconductors and superconducting magnets to flux motion. A simple model based on frictional sliding of conductor is presented to interpret acoustic data; agreement between theory and experiment is good.
66 citations
TL;DR: In this paper, the epicentre location of an elastic half-space has been calculated for force dipoles and combinations of forces representing the formation of point microcracks, the motion of dislocations and dilatation sources.
Abstract: Acoustic emission waveforms for the epicentre location of an elastic half-space have been calculated for force dipoles and combinations of force dipoles representing the formation of point microcracks, the motion of dislocations and dilatation sources. The effects of source orientation, depth and time dependence are shown graphically. These results are used to emphasise the features of acoustic emission signals and their frequency spectra that must be accurately measured if dynamic information or the source type are to be deduced.
63 citations
01 Jul 1983
TL;DR: In this paper, the authors described typical acoustic emission signal characteristics and techniques which localize the signal source by processing the acoustic delay data from multiple sensors are discussed, which includes sensors, amplifiers, pulse counters, a minicomputer and output devices.
Abstract: Typical acoustic emission signal characteristics are described and techniques which localize the signal source by processing the acoustic delay data from multiple sensors are discussed. The instrumentation, which includes sensors, amplifiers, pulse counters, a minicomputer and output devices is examined. Applications are reviewed.
51 citations
TL;DR: In this article, acoustic emission was detected during the undirectional plastic deformation of aluminium alloys 2024 and 2124 with the aim of identifying the sources of the emission, and it was concluded that the fracture of brittle inclusions was the primary source of the acoustic emission detected during tensile testing of the alloys in the temper condition T351.
35 citations
TL;DR: In this paper, an acoustic emission (AE) was detected during fatigue crack propagation in the aluminium alloys 2024-T351 and 2124 T351 with the aim of identifying the source(s) of the emission.
31 citations
TL;DR: A critical review of the application of acoustic emission (AE) to the fabrication, proof testing and in-service monitoring of nuclear pressure vessels is presented in the light of this improved understanding as mentioned in this paper.
30 citations
TL;DR: Acoustic emission monitoring is a non-destructive testing technique that ects ultra-high frequency sound that stressed metal emits as discussed by the authors, where the workpiece is at first under no stress, is elastically deformed (with total springback when pressure is released), or it cracks under too great a pressure.
Abstract: Acoustic emission monitoring is a non-destructive testing technique that ects ultra-high frequency sound that stressed metal emits. In straightening a gun tube the workpiece is at first under no stress, is elastically deformed (with total springback when pressure is released), is plastically deformed (with some springback upon release of pressure), or it cracks under too great a pressure. Each of these stages produces a distinctly different type of acoustic emission. By listening to the workpiece during the pressing operation the operator can be alerted as to the stage the workpiece is in and he can adjust his operation accordingly.
TL;DR: In this article, the effects of heat treatment on the bond between concrete and steel by using direct displacement measurements and monitoring acoustic emission was examined by using acoustic emission and direct displacement measurement.
Abstract: Synopsis Tests were carried out to examine the effects of heat treatment upon the bond between concrete and steel by using direct displacement measurements and monitoring acoustic emission A descr
TL;DR: In this paper, the acoustic emission (AE) signals were monitored during uniaxial loading of symmetrical eight-ply laminates with three different stacking sequences and the peak value and the weighted cumulative count were determined as a function of applied axial stress.
Abstract: The primary object of this study was to investigate acoustic emission (AE) techniques for the detection of progressive damage in graphite/epoxy composite laminates. The AE signals were monitored during the uniaxial loading of symmetrical eight-ply laminates with three different stacking sequences. The peak value and the weighted cumulative count were determined as a function of applied axial stress. Both the peak value data and the cumulative count data are characterized by a pronounced increase at first-ply failure as determined by the Tsai-Hill anisotropic strength criterion, followed by a continuous emission until delamination or final fracture occurs. At the onset of delamination, a pronounced deflection was noted in the accumulated AE signal. Plastic deformation of the matrix generated no significant AE.
TL;DR: In this paper, generalized ray theory for a thick plate driven by a step function point force is compared with experimental waveforms obtained on a glass plate using an improved piezoelectric displacement sensing transducer.
Abstract: Waveforms calculated by generalized ray theory for a thick plate driven by a step‐function point force are compared with experimental waveforms obtained on a glass plate using an improved piezoelectric displacement‐sensing transducer.
TL;DR: In this paper, the origin of acoustic emission in 7075 aluminium alloy was investigated in tension and compression tests and it was suggested that the first peak associated with the root-mean-square (rms) AE plot against time (or strain) is due to unpinning of dislocation segments from solute atom clusters and is not due to the fracture of particles.
Abstract: The origin of acoustic emission (AE) in 7075 aluminium alloy was investigated in tension and compression tests. It is suggested that the first peak associated with the root-mean-square (rms) AE plot against time (or strain) is due to the unpinning of dislocation segments from solute atom clusters and is not due to the fracture of particles. Alteration in the value of the AE first peak and also in electrical resistivity values due to heat treatment of this alloy support the proposed origin of the AE first peak near yield.
01 May 1983
TL;DR: In this paper, a variety of plasma-sprayed oxide coatings subjected to thermal cycling in the range 25 to 650 C were examined to relate acoustic activity to coating failure, and it was suggested that acoustic emission behavior is correlated to phase transformation and cracking.
Abstract: Acoustic emission methodology was used to study a variety of plasma-sprayed oxide coatings subjected to thermal cycling in the range 25 to 650 C. Coatings of Al2O3, TiO2, CaO-stabilized ZrO2, and Y2O3-stabilized ZrO2, sprayed onto one end of a steel substrate, with and without NiCrAl bond coat, were examined to relate acoustic activity to coating failure. Generally, multicomponent coatings produced lower acoustic counts than single component oxide coatings. It is suggested that acoustic emission behavior is correlated to phase transformation and cracking, and shows promise for evaluation of thermal fatigue resistance of plasma-sprayed oxide coatings. 25 references.
Patent•
12 Dec 1983TL;DR: In this paper, a method of determining whether an adhesively bonded joint between two structural elements meets established strength requirements is proposed, in which the combination of directed and focused acoustic energy and application time are selected to macroscopically stress and/or strain-to-failure the minimum acceptable bond strength or less.
Abstract: The invention is a method of determining whether an adhesively bonded joint between two structural elements meets established strength requirements. The method comprises the following steps: (1) Determining by test the levels of acoustic energy to be directed and/or focused by a transducer 12 on a minute area of the adhesively bonded joint 14 and further the application times thereof. The combinations of directed and/or focused acoustic energy and application time are selected to macroscopically stress and/or strain-to-failure the minute area of the adhesively bonded joints having minimum acceptable bond strength or less; (2) Directing and/or focusing by means of a transducer 12 acoustic energy on the minute area of the adhesively bonded joint to be tested and steadily increasing the directed and/or focused acoustic energy/time up to the selected combination which would macroscopically stress and/or strain-to-failure the minute area of the adhesively bonded joint 14 were it of less than minimum acceptable bond strength, and (3) Monitoring by means of one or more focused and/or unfocused acoustic receiver 24 the interaction of the directed and/or focused acoustic energy with the minute area of the adhesively bonded joint 14 and/or the acoustic emission therefrom, a sudden change in the monitored acoustic interaction and/or emission, while the directed and/or focused acoustic energy/time is being steadily increased, indicating bond unacceptability.
TL;DR: In this paper, the authors measured the deformation and fracture of two quaternary Al-5.5wt.%Cu alloys with different grain sizes as a function of aging.
TL;DR: In this paper, a new technique for detecting physically defective multilayer ceramic capacitors is described based upon the acoustic energy emitted when a defective device is subjected to compressional stress.
Abstract: A new technique for detecting physically defective multilayer ceramic capacitors is described. This technique is based upon the acoustic energy emitted when a defective device is subjected to compressional stress. Strong correlation is shown between the acoustic energy emitted and the severity of physical defects as determined through destructive physical analysis. In addition correlation is shown between the presence of physical defects and abnormal performance during accelerated life tests.
TL;DR: In this paper, thermal stress arising from environmental conditions, and structural deformations induced by some recurring stress mechanisms, have been studied for the statue of Marcus Aurelius in Rome.
Abstract: In this experimental work, thermal stress arising from environmental conditions, and structural deformations induced by some recurring stress mechanisms, have been studied for the statue of Marcus Aurelius in Rome. In order to characterize thermal exchange between the monument and the surrounding air, temperature measurements of some significant zones have been recorded with the aid of thermocouples and a thermovision survey of surface temperature distribution was carried out during the course of cooling of the metallic structure and of the stone pedestal. In addition, mechanical stresses have been evaluated by recording pressure waves with an acoustic emission apparatus.
TL;DR: In this article, the amplitude distribution of acoustic emission (AE) from several kinds of plasma-sprayed coatings during four-point bending was studied and it was shown that by means of a χ 2 analysis of the AE pattern, it is possible to discern differences in spraying parameters or substrate preparations much more readily than from either b plots or event counting.
01 Jan 1983
TL;DR: In this article, the authors reviewed the use of acoustic emission (AE) techniques for studying corrosion problems and concluded that the AE method is a prommising approach to the detection and monitoring of localized corrosion in both laboratory specimens and engineering structures.
Abstract: Current theoretical and experimental research on the use of acoustic emission (AE) techniques for studying corrosion problems is reviewed. In particular, attention is given to the AE behavior of Type 304 stainless steel in aqueous environment, and a new method for analyzing corrosion, stress corrosion cracking, and corrosion fatigue in Type 304 steel is described. Results are also presented for other steels, aluminum and magnesium alloys, copper and its alloys, uranium alloys, and titanium and zirconium alloys. It is concluded that the AE method is a prommising approach to the detection and monitoring of localized corrosion in both laboratory specimens and engineering structures. Care must be taken, however, to discriminate valid AE signals from the background noise and to interpret the results correctly. 95 references.
01 Dec 1983
TL;DR: In this article, the effect of prior heat treatment on the mechanical properties, namely the characteristics of plastic deformation, crack initiation and crack propagation, in the low cycle fatigue of AISI 4340 steel was investigated.
TL;DR: In this paper, the authors used an averaging technique to obtain a characteristic acoustic emission signal for a particular type of material and used event timing in conjunction with the data obtained by the analysis of individual signals has led to some speculation on the fracture processes involved.
Abstract: Acoustic emissions from some stressed polypropylene—glass fibre composites have been studied. Pattern recognition has enabled several classes of signal to be identified. These classes and the distribution of the signals in them varies from material to material. By the use of an averaging technique a characteristic acoustic emission signal can be obtained for a particular type of material. Event timing used in conjunction with the data obtained by the analysis of individual signals has led to some speculation on the fracture processes involved.
TL;DR: In this article, the origin of acoustic emission during deformation and fracture of Al-5.5.2.%Zn-2.5wt.%Mg has been studied as a function of aging.
TL;DR: In this article, the authors used stress as the dependent variable instead of the deformation gradient for simple elastic solids and showed that a combination of simple waves and/or shock waves is needed to satisfy the initial and boundary conditions.