A generic technique for acoustic emission source location (original) (raw)
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Fast and Reliable Acoustic Emission Source Location Technique in Complex Structures
Acoustic emission (AE) provides engineers with a powerful tool by allowing the location of damage sources as they occur. Damage localisation using traditional time of arrival approaches is inadequate in complex structure components. Cardiff University presented a novel approach known as Delta-T mapping which overcame these limitations but it was considered as time consuming and an operator dependent approach. This paper presents new full automatic Delta-T mapping technique overcomes these remaining limitations.
Proceedings of the 9th International Conference on Fracture Mechanics of Concrete and Concrete Structures, 2016
FastWay is a novel method for source localization of acoustic emissions (AE) in complex solid media. It uses the fastest, rather than the shortest wave path between the AE source and the recording sensors. In this paper we investigate the potential of this method for acoustic emission source localization in concrete structures. To consider the influence on the wave propagation of both the concrete heterogeneity and the possible cracks present in the tested specimen, a heterogeneous velocity model was selected and a multi-segment path analysis based on this model was performed. After validating the model numerically using simulated AE sources, laboratory experiments were conducted on a small concrete beam (152 mm × 152 mm × 533 mm) with a predefined notch cut to serve as a material discontinuity (crack). Artificial AE sources using pencil-lead breaks were applied on a 25.4 mm × 25.4 point grid mapped on the surface of the beam. To evaluate the performance of FastWay, a set of sources randomly selected were picked and localization results using both FastWay and Geiger's method compared. The results obtained show that FastWay performs more reliably and accurately than Geiger's algorithm even in the presence of cracks and air inclusions. No major influence of these two factors was seen on the localization results. The influence considered the most crucial, however, is of the velocity model which strongly depends on the complex internal structure of the tested specimen.
Acoustic emission source location in composite materials using Delta T Mapping
Composites Part A: Applied Science and Manufacturing, 2012
The location capability of the Acoustic Emission (AE) technique is often considered its most powerful attribute. However, assumptions made in the calculation of location by current algorithms can be limiting in complex geometries and materials. This work forms a detailed study into the use of a novel mapping technique for AE source location in fibre reinforced composite materials. Both the performance and the robustness of the approach are assessed using artificial and real AE sources. Furthermore a large fatigue specimen was used to demonstrate detection and location of damage onset and development, where findings were validated using a thermo-elastic stress analysis (TSA) system. Substantial improvements in location accuracy were observed and early detection of damage onset was seen to outperform TSA.
Acoustic emission non-destructive testing of structures using source location techniques
2013
The technology of acoustic emission (AE) testing has been advanced and used at Sandia for the past 40 years. AE has been used on structures including pressure vessels, fire bottles, wind turbines, gas wells, nuclear weapons, and solar collectors. This monograph begins with background topics in acoustics and instrumentation and then focuses on current acoustic emission technology. It covers the overall design and system setups for a test, with a wind turbine blade as the object. Test analysis is discussed with an emphasis on source location. Three test examples are presented, two on experimental wind turbine blades and one on aircraft fire extinguisher bottles. Finally, the code for a FORTRAN source location program is given as an example of a working analysis program. Throughout the document, the stress is on actual testing of real structures, not on laboratory experiments. *The work described in this report was performed for Sandia National Laboratories under Contract No. 1145363.
State-of-the-Art Review on the Acoustic Emission Source Localization Techniques
IEEE ACCESS, 2021
The acoustic emission technique has been applied successfully for the identification, characterization, and localization of deformations in civil engineering structures. Numerous localization techniques, such as Modal Acoustic Emission, Neural Networks, Beamforming, and Triangulation methods with or without prior knowledge of wave velocity, have been presented. Several authors have conducted in-depth research in the localization of AE sources. However, existing review papers do not focus on the performance evaluation of existing source localization techniques. This paper discusses these techniques based on the number of sensors used and the geometry of the structures of interest. Furthermore, it evaluates them on the basis of their performance. At the end of this paper, a comparative analysis of existing methods has been presented based on their basic principles, key strengths, and limitations. A deep learning circular sensor cluster-based solution has the potential to provide a low-cost reliable localization solution for acoustic emission sources.
Location of pointlike acoustic emission sources in anisotropic plates
The Journal of the Acoustical Society of America, 1989
In this paper is described a method by which a pointlike source of acoustic emission can be located in an anisotropic plate. The method is applicable for a source in an anisotropic solid of arbitrary symmetry as long as the principal acoustic axes of the material are known a priori. It is shown that from the time-of-flight differences of particular features in the waveforms detected by any pair of sensors, a set of nonlinear transcendental equations can be formed in which the coefficient of each term in the equations is related to the time-of-flight differences, the geometrical parameters of the array, and the wave speeds of quasiwaves propagating along each source/receiver path. For waves propagating in principal planes, the analytical expressions for the wave speed values are used. Extension to nonprincipal planes is obtained by computing the eigenvalues of the Green-Christoffel tensor. Determination of the optimum location of the source is found by minimizing the Euclidean functional associated with the set of transcendental nonlinear equations. The results obtained with numerical simulations of twoand three-dimensional source-location problems are presented to illustrate several characteristic features of the solution. Also shown are the results of two-dimensional sourcelocation measurements made on specimens of a unidirectional fiberglass reinforced composite material. The results demonstrate the efficiency ,of the algorithm in locating a source of emission.
Mechanical Systems and Signal Processing, 2015
This paper presents a probabilistic framework for acoustic emission (AE) source localization in cylindrical structures. Specifically, an approach based on unscented transformation (UT) is proposed to take into account uncertainty in time of flight measurements and wave velocity and eventually estimate AE source locations together with quantitative measures of confidence associated with those estimates. Experiments are carried out on a steel pipe instrumented with an array of six embedded piezoelectric disks. Results are compared with Monte Carlo simulations by the Kullback-Leibler divergence.
One sensor linear location of acoustic emission events using plate wave theories
Materials Science and Engineering: A, 1999
Acoustic emissions (AE) are transient stress waves generated in a material under load upon damage formation. By detecting these waves and analysing their properties, information can be obtained about the damage initiation and propagation in loaded structures. The AE technique possesses a number of distinct advantages, one of which is the possibility to calculate the spatial source location based on arrival time differences between a number of sensors. In this way, the use of two sensors allows for a linear source location. This paper will demonstrate how taking into account the modal nature of AE signals can be used to reduce the number of sensors needed in AE source location. Using signals obtained during tensile and bending tests performed on a number of cross-ply and unidirectional carbon fibre reinforced polymer (CFRP) lay-ups, it will be shown how a linear source location can be calculated using one sensor. To achieve this goal two different plate wave theories will be used and the results will be compared to the ones obtained by a traditional two sensor linear location scheme.
Intelligent location of simultaneously active acoustic emission sources: Part II
2007
Part I describes an intelligent acoustic emission locator, while Part II discusses blind source separation, time delay estimation and location of two continuous acoustic emission sources. Acoustic emission (AE) analysis is used for characterization and location of developing defects in materials. AE sources often generate a mixture of various statistically independent signals. A difficult problem of AE analysis is separation and characterization of signal components when the signals from various sources and the mode of mixing are unknown. Recently, blind source separation (BSS) by independent component analysis (ICA) has been used to solve these problems. The purpose of this paper is to demonstrate the applicability of ICA to locate two independent simultaneously active acoustic emission sources on an aluminum band specimen. The method is promising for non-destructive testing of aircraft frame structures by acoustic emission analysis.