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1
المؤلفون: Kevin Lontin, Muhammad Ali Khan
المصدر: Friction. 9:1319-1345
مصطلحات موضوعية: wear, Mathematical model, Computer science, Mechanical Engineering, media_common.quotation_subject, friction, Mechanical engineering, 02 engineering and technology, 021001 nanoscience & nanotechnology, Surfaces, Coatings and Films, Interdependence, Noise, 020303 mechanical engineering & transports, 0203 mechanical engineering, Acoustic emission, acoustic emission, 0210 nano-technology, media_common
الوصف: Phenomena of friction, wear, and noise in mechanical contacts are particularly important in the field of tribomechanics but equally complex if one wants to represent their exact relationship with mathematical models. Efforts have been made to describe these phenomena with different approaches in past. These efforts have been compiled in different reviews but most of them treated friction, wear mechanics, and acoustic noise separately. However, an in-depth review that provides a critical analysis on their interdependencies is still missing. In this review paper, the interdependencies of friction, wear, and noise are analysed in the mechanical contacts at asperitical level. The origin of frictional noise, its dependencies on contact’s mechanical properties, and its performance under different wear conditions are critically reviewed. A discussion on the existing mathematical models of friction and wear is also provided in the last section that leads to uncover the gap in the existing literature. This review concludes that still a comprehensive analytical modelling approach is required to relate the interdependencies of friction, noise, and wear with mathematical expressions.
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2
المصدر: Materials Science Forum. 1040:101-108
مصطلحات موضوعية: Materials science, business.industry, Mechanical Engineering, 0211 other engineering and technologies, Mechanical engineering, 02 engineering and technology, Condensed Matter Physics, 020303 mechanical engineering & transports, 0203 mechanical engineering, Acoustic emission, Mechanics of Materials, Nondestructive testing, General Materials Science, Resource assessment, business, 021102 mining & metallurgy
الوصف: The strength of materials is determined by their atomic molecular structure and the process of decay of atomic molecular bonds, which must be taken into account when optimizing materials strength control technologies. The fracture photomicrograph of metal microdamage of welded joint at various moments of time, a multilevel model of flow of acoustic emission signals of materials are presented. The physical meaning, the scale level of parameters included in the model are revealed. The structure of the mathematical model of the flow of AE signals with components of its informative elements of different scale level by strength characteristics of structural materials and resource of technical objects is shown. The multilevel model of the AE signal flow is hierarchically structured, obtained by generalizing deterministic-statistical variability. It describes the process of randomly recording deterministic accumulated damages in the material both before and after the formation of a crack at the stage of waiting for its next leap. It is shown that the proposed nanotechnology of strength control of materials is reduced to non-destructive determination of parameters of prognostic homogeneous destruction, identification of which is based on multilevel modeling of time dependence of micro-crack formation, formulation of criterion of strength homogeneity, registration of AE parameters related to the model of a specific product, which can be automated processing of registration results and determination of universal strength nanoconstants from already published reference data of fatigue tests of standard material samples.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_________::e13c2233016ee1063c265d94589938c6
https://doi.org/10.4028/www.scientific.net/msf.1040.101 -
3
المؤلفون: Hiroshi Murakami, Akio Katsuki, Yuta Sugihara, Keisuke Houda, Takao Sajima, Kosuke Uchiyama
المصدر: Precision Engineering. 70:26-33
مصطلحات موضوعية: 0209 industrial biotechnology, business.product_category, Materials science, Acoustics, General Engineering, 02 engineering and technology, Signal, Turbine, Machine tool, Surface micromachining, 020303 mechanical engineering & transports, 020901 industrial engineering & automation, Air bearing, 0203 mechanical engineering, Acoustic emission, Machining, business, Microfabrication
الوصف: Recently, the demand for realizing micromachining through small-diameter tools has increased. When performing microfabrication using a numerically controlled machine tool, a machining error may be introduced if the relative position of the tool tip and workpiece surface deviates during tool change. Therefore, it is critical to determine this relative position in an actual machining condition at a specific spindle speed. We are currently developing an air bearing turbine spindle with a built-in acoustic emission sensor that can detect the contact of the tool tip with the workpiece surface in real time. The acoustic emission (AE) signal generated at the tool tip can be accurately detected by placing the AE sensor in direct contact with the tool end surface inside the main shaft floated by air. In this study, we investigated the possibility of contact detection between the tool tip and the workpiece surface at the submicrometer level through the proposed spindle. The results of the performed evaluation experiments indicated that by using the spindle with a built-in acoustic emission sensor, the contact of the small-diameter tool tip with the workpiece surface could be detected with damage to the workpiece at the submicrometer level on average.
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4
المؤلفون: Kilian Wasmer, Markus Varga, Josef Prost, Vigneashwara Pandiyan, G. Vorlaufer
المصدر: Friction. 10:583-596
مصطلحات موضوعية: business.industry, Computer science, Microphone, Wear and tear, Mechanical Engineering, Condition monitoring, 02 engineering and technology, 021001 nanoscience & nanotechnology, Machine learning, computer.software_genre, Convolutional neural network, Autoencoder, Signal, Surfaces, Coatings and Films, Identification (information), 020303 mechanical engineering & transports, 0203 mechanical engineering, Acoustic emission, Artificial intelligence, 0210 nano-technology, business, Algorithm, computer
الوصف: Functional surfaces in relative contact and motion are prone to wear and tear, resulting in loss of efficiency and performance of the workpieces/machines. Wear occurs in the form of adhesion, abrasion, scuffing, galling, and scoring between contacts. However, the rate of the wear phenomenon depends primarily on the physical properties and the surrounding environment. Monitoring the integrity of surfaces by offline inspections leads to significant wasted machine time. A potential alternate option to offline inspection currently practiced in industries is the analysis of sensors signatures capable of capturing the wear state and correlating it with the wear phenomenon, followed by in situ classification using a state-of-the-art machine learning (ML) algorithm. Though this technique is better than offline inspection, it possesses inherent disadvantages for training the ML models. Ideally, supervised training of ML models requires the datasets considered for the classification to be of equal weightage to avoid biasing. The collection of such a dataset is very cumbersome and expensive in practice, as in real industrial applications, the malfunction period is minimal compared to normal operation. Furthermore, classification models would not classify new wear phenomena from the normal regime if they are unfamiliar. As a promising alternative, in this work, we propose a methodology able to differentiate the abnormal regimes, i.e., wear phenomenon regimes, from the normal regime. This is carried out by familiarizing the ML algorithms only with the distribution of the acoustic emission (AE) signals captured using a microphone related to the normal regime. As a result, the ML algorithms would be able to detect whether some overlaps exist with the learnt distributions when a new, unseen signal arrives. To achieve this goal, a generative convolutional neural network (CNN) architecture based on variational auto encoder (VAE) is built and trained. During the validation procedure of the proposed CNN architectures, we were capable of identifying acoustics signals corresponding to the normal and abnormal wear regime with an accuracy of 97% and 80%. Hence, our approach shows very promising results for in situ and real-time condition monitoring or even wear prediction in tribological applications.
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5
المصدر: Structural Health Monitoring. 21:1235-1250
مصطلحات موضوعية: Materials science, Mechanical Engineering, Acoustics, Fast Fourier transform, Biophysics, Cross correlation analysis, Phase (waves), 02 engineering and technology, 021001 nanoscience & nanotechnology, law.invention, 020303 mechanical engineering & transports, 0203 mechanical engineering, Acoustic emission, law, Geiger counter, Structural health monitoring, 0210 nano-technology
الوصف: Nowadays, the localization and identification of acoustic emission (AE) source is widely utilized to structural health monitoring (SHM) of complex metallic structures. However, traditional AE source localization methods are generally difficult to localize and characterize AE sources in plate-like structure that has complex geometric features. To alleviate the problem, a novel AE source localization method based on all-phase fast Fourier transform and multiple cross-correlation analysis is proposed in this article. Moreover, least squares and Geiger iteration algorithm are applied to determine the coordinates of AE sources. In addition, an improved Bayesian information criterion (BIC) version named autoregressive BIC (i.e., AR-BIC) is presented to increase the accuracy of source localization. To validate the performance of the proposed approach, the classical pencil lead break tests are carried out on a 316 L stainless steel with 10 laser cladding layers. Experimental waveforms are generated from AE sources near laser cladding layers, the surface of the structure, and on its edges. Additionally, to evaluate the performance of the proposed approach in three-dimensional AE source localization, an industrial storage tank is used to acquire three-dimensional AE sources through manually striking. Finally, to further verify the effectiveness of the proposed approach, comparisons with conventional AE source location methods (i.e., PAC or SAMOS AE acquisition system, Newton’s method, and multiple cross-correlation based on Geiger algorithm) and two representative approaches (i.e., deep learning and Bayesian methodology) for localizing AE sources generated by complex metallic structures are conducted. The comparative results demonstrate the effectiveness and superiority of the proposed method in AE-based SHM of complex metallic structures.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_________::8bacf55831f76bbf3dc24b70c444a9e5
https://doi.org/10.1177/14759217211027481 -
6
المؤلفون: Jianguo Ning, Keqin Ding, Zonglian Wang, Huilan Ren
المصدر: Structural Health Monitoring. 21:1046-1060
مصطلحات موضوعية: Frequency analysis, Materials science, Mechanical Engineering, Acoustics, 0211 other engineering and technologies, Biophysics, Process (computing), 02 engineering and technology, Bending, Wavelet packet decomposition, law.invention, 020303 mechanical engineering & transports, 0203 mechanical engineering, Acoustic emission, law, 021105 building & construction
الوصف: To gain an insight into the evolution of micro-cracks in concrete materials, a quantitative acoustic emission investigation on the damage process of concrete prisms subjected to three-point bending loading was performed. Each of the monitored acoustic emission signals was processed by a two-level wavelet packet decomposition into four different frequency bands (AA2, DA2, AD2, and DD2), and the energy coefficients R1, R2, R3, and R4 that parameterize their characteristic frequency bands were calculated. By analyzing variations in energy coefficients of the lowest frequency band (AA2), R1, and the energy coefficients of the highest frequency band (DD2), R4, the whole damage process was divided into three stages: crack initiation, crack growth, and crack coalescence. An inverse relationship between the frequency of the acoustic emission signal emitted by the propagating crack and the crack size in concrete materials was acquired based on the damage theory of brittle materials and the strain energy release theory. The statistical analysis results of the experimental data indicated that the average of R1 increased in turn, and the average of R4 correspondingly decreased in turn from Stage 1 to Stage 3. It revealed that the frequencies of acoustic emission signals decreased gradually with the evolution of the damage of concrete prisms, which is in a good agreement with the theoretical analysis result.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_________::e3510916e6b951b79ec46dcae723a407
https://doi.org/10.1177/14759217211018871 -
7Experimental study on the damage process of marble under true triaxial pre-peak unloading conditions
المؤلفون: Zhaofeng Wang, Yaohui Gao
المصدر: International Journal of Damage Mechanics. 30:1542-1557
مصطلحات موضوعية: Materials science, Mechanical Engineering, 0211 other engineering and technologies, Computational Mechanics, Process (computing), 02 engineering and technology, Dissipation, Instability, Pre peak, 020303 mechanical engineering & transports, Brittleness, 0203 mechanical engineering, Acoustic emission, Mechanics of Materials, General Materials Science, Geotechnical engineering, 021101 geological & geomatics engineering
الوصف: Stress-induced instability is associated with rock damage. Here, the progressive brittle fracturing process in Jinping marble is studied by introducing two types of true triaxial pre-peak unloading tests, namely, the incrementally cyclic loading-unloading minimum principal stress test (ICM test) and the incrementally cyclic loading-unloading maximum and minimum principal stress test (ICMM test). By comprehensively analysing the irreversible strains, dissipated energy, acoustic emission (AE) characteristics and scanning electron microscopy (SEM) results, the rock damage evolution can be quantified and divided into two distinctive damage stages. At the boundary point, the irreversible strain increments reach their minimum values. In the gentle damage stage, the normalized irreversible strains increase linearly, and this process is associated with a small number of AE hits with low amplitude. The rapid damage stage is characterized by a nonlinear increase in the normalized irreversible strains, and this process is associated with a large number of AE hits with high amplitude. The dissipated energy mainly increases in the rapid damage stage. In addition, the rapid damage stage in the ICMM test mainly occurs in the last five cycles, due to the differences in the deviatoric stresses in each cycle. In both of these tests, the failure mode is principally characterized by tensile failure. Moreover, the precursory signals of rock fracturing and the influence of the loading paths on the strength are discussed.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_________::1a5b40577478488aeb84ca06c26effd8
https://doi.org/10.1177/10567895211020799 -
8
المؤلفون: Lu Wang, Jianfeng Liu, Deng Chaofu, Zhide Wu, Hejuan Liu, Fukun Xiao, Anqi Zhu
المصدر: Advances in Civil Engineering, Vol 2021 (2021)
مصطلحات موضوعية: Yield (engineering), Materials science, Article Subject, Tension (physics), 0211 other engineering and technologies, 02 engineering and technology, Dissipation, Engineering (General). Civil engineering (General), 020303 mechanical engineering & transports, 0203 mechanical engineering, Acoustic emission, Ultimate tensile strength, Fracture (geology), TA1-2040, Composite material, Deformation (engineering), Displacement (fluid), 021101 geological & geomatics engineering, Civil and Structural Engineering
الوصف: Salt rock has been regarded as the optimal surrounding rock for underground gas storage (UGS), and it is occasionally subjected to cyclic tension because of the gas injection and production of salt cavern, which leads to the change in mechanical properties of salt rock. In this paper, a laboratory study is conducted to investigate the energy dissipation and damage evolution characteristics of salt rock under uniaxial cyclic tension monitored by acoustic emission (AE) machine. Compared to monotonic tension, both tensile strength and deformation capacity of salt rock are enhanced under cyclic tension. The fracture crack is approximately a single linear crack with large elliptical plastic deformation zone, which is consistent with the spatial distribution of AE events. In yield stage, the proportion of dissipative energy increases first but decreases subsequently. The relationship between AE energy-based damage variable and displacement is established. It is concluded that the damage variable is a piecewise power correlation with displacement while the growth rate of damage variable increases in the pre-peak stage but decreases in post-peak stage.
وصف الملف: text/xhtml
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المؤلفون: O.V. Bashkov, Daria P. Malysheva, A.A. Bryansky, Denis B. Solovev
المصدر: Key Engineering Materials. 887:116-122
مصطلحات موضوعية: Materials science, Mechanical Engineering, 02 engineering and technology, Polymer composite materials, Bending, 021001 nanoscience & nanotechnology, 020303 mechanical engineering & transports, 0203 mechanical engineering, Acoustic emission, Mechanics of Materials, Ultimate tensile strength, General Materials Science, Composite material, 0210 nano-technology
الوصف: The paper presents the results of the study of registered acoustic emission (AE) parameters during static deformation and damaging of polymer composite materials (PCM). Mechanical tests were done by a static tension and a static three-point bend, accompanied by an acoustic emission method. The assessment of the loading rate effect on defects formation processes was done by additional static tension test at rate equal half of recommended by the standard and static three-point bend test at rate ten times lower than that calculated by the standard. Clustering by frequency components of the recorded AE signals with a self-organizing Kohonen map was performed. The characteristics of the types of PCM structure damage by the centroids of the obtained clusters are given. Based on the clusters accumulation during mechanical tests, the stages of damage formation for static tension and static three-point bend, the loading rate effect on the process of damage formation are described.
URL الوصول: https://explore.openaire.eu/search/publication?articleId=doi_________::65e86bfe149bf10d96735eda353bd10f
https://doi.org/10.4028/www.scientific.net/kem.887.116 -
10
المصدر: Sensors, Vol 21, Iss 145, p 145 (2021)
Sensors
Volume 21
Issue 1
Sensors (Basel, Switzerland)مصطلحات موضوعية: Materials science, Piezoelectric sensor, Instrumentation, 02 engineering and technology, recycling, mechanical properties, lcsh:Chemical technology, Biochemistry, composites, Displacement (vector), Article, Analytical Chemistry, 0203 mechanical engineering, K-S metric entropy, lcsh:TP1-1185, Electrical and Electronic Engineering, Composite material, Entropy (energy dispersal), Tensile testing, 021001 nanoscience & nanotechnology, Atomic and Molecular Physics, and Optics, 020303 mechanical engineering & transports, Acoustic emission, Metric (mathematics), 0210 nano-technology, acoustic emission, Extensometer
الوصف: Due to the unique properties of polymer composites, these materials are used in many industries, including shipbuilding (hulls of boats, yachts, motorboats, cutters, ship and cooling doors, pontoons and floats, torpedo tubes and missiles, protective shields, antenna masts, radar shields, and antennas, etc.). Modern measurement methods and tools allow to determine the properties of the composite material, already during its design. The article presents the use of the method of acoustic emission and Kolmogorov&ndash
Sinai (K-S) metric entropy to determine the mechanical properties of composites. The tested materials were polyester-glass laminate without additives and with a 10% content of polyester-glass waste. The changes taking place in the composite material during loading were visualized using a piezoelectric sensor used in the acoustic emission method. Thanks to the analysis of the RMS parameter (root mean square of the acoustic emission signal), it is possible to determine the range of stresses at which significant changes occur in the material in terms of its use as a construction material. In the K-S entropy method, an important measuring tool is the extensometer, namely the displacement sensor built into it. The results obtained during the static tensile test with the use of an extensometer allow them to be used to calculate the K-S metric entropy. Many materials, including composite materials, do not have a yield point. In principle, there are no methods for determining the transition of a material from elastic to plastic phase. The authors showed that, with the use of a modern testing machine and very high-quality instrumentation to record measurement data using the Kolmogorov&ndash
Sinai (K-S) metric entropy method and the acoustic emission (AE) method, it is possible to determine the material transition from elastic to plastic phase. Determining the yield strength of composite materials is extremely important information when designing a structure.وصف الملف: application/pdf
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