ABSTRACT Acoustic emission is widely used for mechanical diagnostics and to characterise damage i... more ABSTRACT Acoustic emission is widely used for mechanical diagnostics and to characterise damage in composite materials. Distinction between different damage mechanisms is still one of the major challenges and remains an unresolved issue. The objective of cluster analysis is to separate an acoustic emission data set into multiple classes that reflect different acoustic emission sources. This article is concerned with the implementation of unsupervised clustering techniques to classify acoustic emission transients from a carbon fibre laminate buckling test. A new approach to signal feature extraction was utilised, whereby principal components provide signal features that represent the greatest data variance while remaining linearly uncorrelated with each other; feature selection was undertaken using a hierarchical clustering method and finally a cluster analysis was performed using k-means and Fuzzy C-means techniques. The aim of the work is to reduce the data required in the classification process, thereby reducing the processing time and computational power required, without significantly affecting the classification result. Thus, an approach which is more suited to online processing, allowing fast and efficient processing and storage of data is provided. The proposed unsupervised clustering analysis was able to separate acoustic emission signals into two different clusters that were correlated to the damage mechanisms observed. The results show that the clustering groups have a good fit with ultrasonic C-scan and digital image correlation strain data. The application of a clustering process that uses the most effective acoustic emission features as input data is an objective method, and this investigation shows that it may be a useful complement in the field of non-destructive evaluation.
Fatigue & Fracture of Engineering Materials & Structures, 2014
ABSTRACT Recent developments in shot peening demonstrate that it can be applied using unconventio... more ABSTRACT Recent developments in shot peening demonstrate that it can be applied using unconventional parameters in order to obtain nanocrystals on a thin surface layer of the treated material. These microstructural modifications have shown to be able to induce superior fatigue and corrosion properties, but still few data are available about their effect on wear behaviour of the materials.In this study, four series of Al 6063 alloy specimens, as-received, conventionally shot peened, severely shot peened and severely shot peened followed by a slight mechanical grinding are subjected to block on ring wear tests with lubrication, according to ASTM G77 standard. The results evidence the significant role played by the applied shot peening treatments on wear behaviour of the 6063 aluminium alloy with respect to the as-received not peened material. The important effect of the surface roughness is also highlighted. The data are discussed on the basis of roughness, surface layer microstructure, microhardness trends and the wear marks observed by means of scanning electron microscopy.
Conference Proceedings of the Society for Experimental Mechanics Series, 2013
ABSTRACT In this study the effect of cold spray deposition of similar material on the Al 6082 all... more ABSTRACT In this study the effect of cold spray deposition of similar material on the Al 6082 alloy substrate is investigated. High deposition pressure which enhances coating cohesion and peening effect was used for cold spraying. Micro-structural observation, micro-hardness measurements and X-Ray diffraction (XRD) measurement of residual stress were performed on the sprayed material. Rotating bending fatigue limit of the cold sprayed specimen was experimentally determined and compared with the as-received specimens. The results showed that the cold spray process developed significant compressive residual stress in both deposited material and the substrate. Cold spray Coating is able to increase the fatigue limit by 14.7 %. No significant delamination between coating and substrate was found by scanning electron microscopy observation of the fractured surface. The result of this paper confirms that the cold spray coatings can successfully contribute to carrying applied loads. This affirms the possible application of the cold spray process of the similar materials for repairing the damage parts.
Journal of Mechanical Systems for Transportation and Logistics, 2010
The ability to predict the criticality of internal cracks in railway wheels requires accurate kno... more The ability to predict the criticality of internal cracks in railway wheels requires accurate knowledge of stress intensity factors KI, KII, KIII under contact loads. These factors depend both on the total load acting on the wheel and on how the load is transmitted through the wheel/rail interface, that is to say, they depends on the pressure distribution between wheel
Abstract. The effectiveness of the application of shot peening after nitirding for improving the ... more Abstract. The effectiveness of the application of shot peening after nitirding for improving the fatigue strength of high-performance steel components has not been adequately treated in literature, and it is not clear if shot peening can really and drastically increase mechanical ...
50 Experimental Techniques and Design in Composite Materials 5 In this paper this aspect is inves... more 50 Experimental Techniques and Design in Composite Materials 5 In this paper this aspect is investigated: a 7005 Al alloy reinforced with 10% alumina particles is considered. Fatigue crack propagation tests in the near-threshold regime are carried out according to two different ...
Cell-substrate interface is known to control the cell response and subsequent cell functions. Amo... more Cell-substrate interface is known to control the cell response and subsequent cell functions. Among the various biophysical signals, grain structure, which indicates the repeating arrangement of atoms in the material, has also proved to play a role of significant importance in mediating the cell activities. Moreover, refining the grain size through severe plastic deformation is known to provide the processed material with novel mechanical properties. The potential application of such advanced materials as biomedical implants has recently been evaluated by investigating the effect of different substrate grain sizes on a wide variety of cell activities. In this review, recent advances in biomedical applications of severe plastic deformation techniques are highlighted with special attention to the effect of the obtained nano/ultra-fine-grain size on cell-substrate interactions. Various severe plastic deformation techniques used for this purpose are discussed presenting a brief descript...
... J Japan Inst Metals 2006; 70:415–19. [10] Bagherifard S, Ghelichi R, Guagliano M. A numerical... more ... J Japan Inst Metals 2006; 70:415–19. [10] Bagherifard S, Ghelichi R, Guagliano M. A numericalmodel of severe shot peening (SSP) to predict the generation of a nanostructured surface layer of material. Surface & Coatings Technology 2010; 204: 4081–90. ...
Pultrusion is a promising technique for manufacturing composite materials in the form of constant... more Pultrusion is a promising technique for manufacturing composite materials in the form of constant-section profiles, which allows to obtain these products in a highly automated way and with an overall good fiber alignment and cohesion. This material is used in civil and structural applications, but its development is being slowed down due to the fact that different types of damage can suddenly develop during the loading of the structure, leading to unexpected failure.
The objective of the study is to identify the damage modes evolving in pultruded glass-fiber reinforced polymers during static tensile tests. The experimental campaign consists of 34 static tensile specimens with two different layups. During each test, Acoustic Emission data is recorded to assess the different characteristics of the signals and their location.
A Self Organizing Map, clustered with the k-means algorithm, was used for retrieving classes of similar signals in the dataset. The evolution of damage and energy content of each class was followed during the test; this allowed identifying and separating different damage modes.
Moreover, the possibility to apply unsupervised neural network clustering techniques to the AE data is investigated; this is used to filter out the signals which aren’t linkable to a material degradation.
ABSTRACT Acoustic emission is widely used for mechanical diagnostics and to characterise damage i... more ABSTRACT Acoustic emission is widely used for mechanical diagnostics and to characterise damage in composite materials. Distinction between different damage mechanisms is still one of the major challenges and remains an unresolved issue. The objective of cluster analysis is to separate an acoustic emission data set into multiple classes that reflect different acoustic emission sources. This article is concerned with the implementation of unsupervised clustering techniques to classify acoustic emission transients from a carbon fibre laminate buckling test. A new approach to signal feature extraction was utilised, whereby principal components provide signal features that represent the greatest data variance while remaining linearly uncorrelated with each other; feature selection was undertaken using a hierarchical clustering method and finally a cluster analysis was performed using k-means and Fuzzy C-means techniques. The aim of the work is to reduce the data required in the classification process, thereby reducing the processing time and computational power required, without significantly affecting the classification result. Thus, an approach which is more suited to online processing, allowing fast and efficient processing and storage of data is provided. The proposed unsupervised clustering analysis was able to separate acoustic emission signals into two different clusters that were correlated to the damage mechanisms observed. The results show that the clustering groups have a good fit with ultrasonic C-scan and digital image correlation strain data. The application of a clustering process that uses the most effective acoustic emission features as input data is an objective method, and this investigation shows that it may be a useful complement in the field of non-destructive evaluation.
Fatigue & Fracture of Engineering Materials & Structures, 2014
ABSTRACT Recent developments in shot peening demonstrate that it can be applied using unconventio... more ABSTRACT Recent developments in shot peening demonstrate that it can be applied using unconventional parameters in order to obtain nanocrystals on a thin surface layer of the treated material. These microstructural modifications have shown to be able to induce superior fatigue and corrosion properties, but still few data are available about their effect on wear behaviour of the materials.In this study, four series of Al 6063 alloy specimens, as-received, conventionally shot peened, severely shot peened and severely shot peened followed by a slight mechanical grinding are subjected to block on ring wear tests with lubrication, according to ASTM G77 standard. The results evidence the significant role played by the applied shot peening treatments on wear behaviour of the 6063 aluminium alloy with respect to the as-received not peened material. The important effect of the surface roughness is also highlighted. The data are discussed on the basis of roughness, surface layer microstructure, microhardness trends and the wear marks observed by means of scanning electron microscopy.
Conference Proceedings of the Society for Experimental Mechanics Series, 2013
ABSTRACT In this study the effect of cold spray deposition of similar material on the Al 6082 all... more ABSTRACT In this study the effect of cold spray deposition of similar material on the Al 6082 alloy substrate is investigated. High deposition pressure which enhances coating cohesion and peening effect was used for cold spraying. Micro-structural observation, micro-hardness measurements and X-Ray diffraction (XRD) measurement of residual stress were performed on the sprayed material. Rotating bending fatigue limit of the cold sprayed specimen was experimentally determined and compared with the as-received specimens. The results showed that the cold spray process developed significant compressive residual stress in both deposited material and the substrate. Cold spray Coating is able to increase the fatigue limit by 14.7 %. No significant delamination between coating and substrate was found by scanning electron microscopy observation of the fractured surface. The result of this paper confirms that the cold spray coatings can successfully contribute to carrying applied loads. This affirms the possible application of the cold spray process of the similar materials for repairing the damage parts.
Journal of Mechanical Systems for Transportation and Logistics, 2010
The ability to predict the criticality of internal cracks in railway wheels requires accurate kno... more The ability to predict the criticality of internal cracks in railway wheels requires accurate knowledge of stress intensity factors KI, KII, KIII under contact loads. These factors depend both on the total load acting on the wheel and on how the load is transmitted through the wheel/rail interface, that is to say, they depends on the pressure distribution between wheel
Abstract. The effectiveness of the application of shot peening after nitirding for improving the ... more Abstract. The effectiveness of the application of shot peening after nitirding for improving the fatigue strength of high-performance steel components has not been adequately treated in literature, and it is not clear if shot peening can really and drastically increase mechanical ...
50 Experimental Techniques and Design in Composite Materials 5 In this paper this aspect is inves... more 50 Experimental Techniques and Design in Composite Materials 5 In this paper this aspect is investigated: a 7005 Al alloy reinforced with 10% alumina particles is considered. Fatigue crack propagation tests in the near-threshold regime are carried out according to two different ...
Cell-substrate interface is known to control the cell response and subsequent cell functions. Amo... more Cell-substrate interface is known to control the cell response and subsequent cell functions. Among the various biophysical signals, grain structure, which indicates the repeating arrangement of atoms in the material, has also proved to play a role of significant importance in mediating the cell activities. Moreover, refining the grain size through severe plastic deformation is known to provide the processed material with novel mechanical properties. The potential application of such advanced materials as biomedical implants has recently been evaluated by investigating the effect of different substrate grain sizes on a wide variety of cell activities. In this review, recent advances in biomedical applications of severe plastic deformation techniques are highlighted with special attention to the effect of the obtained nano/ultra-fine-grain size on cell-substrate interactions. Various severe plastic deformation techniques used for this purpose are discussed presenting a brief descript...
... J Japan Inst Metals 2006; 70:415–19. [10] Bagherifard S, Ghelichi R, Guagliano M. A numerical... more ... J Japan Inst Metals 2006; 70:415–19. [10] Bagherifard S, Ghelichi R, Guagliano M. A numericalmodel of severe shot peening (SSP) to predict the generation of a nanostructured surface layer of material. Surface & Coatings Technology 2010; 204: 4081–90. ...
Pultrusion is a promising technique for manufacturing composite materials in the form of constant... more Pultrusion is a promising technique for manufacturing composite materials in the form of constant-section profiles, which allows to obtain these products in a highly automated way and with an overall good fiber alignment and cohesion. This material is used in civil and structural applications, but its development is being slowed down due to the fact that different types of damage can suddenly develop during the loading of the structure, leading to unexpected failure.
The objective of the study is to identify the damage modes evolving in pultruded glass-fiber reinforced polymers during static tensile tests. The experimental campaign consists of 34 static tensile specimens with two different layups. During each test, Acoustic Emission data is recorded to assess the different characteristics of the signals and their location.
A Self Organizing Map, clustered with the k-means algorithm, was used for retrieving classes of similar signals in the dataset. The evolution of damage and energy content of each class was followed during the test; this allowed identifying and separating different damage modes.
Moreover, the possibility to apply unsupervised neural network clustering techniques to the AE data is investigated; this is used to filter out the signals which aren’t linkable to a material degradation.
Uploads
Papers by MARIO GUAGLIANO
The objective of the study is to identify the damage modes evolving in pultruded glass-fiber reinforced polymers during static tensile tests. The experimental campaign consists of 34 static tensile specimens with two different layups. During each test, Acoustic Emission data is recorded to assess the different characteristics of the signals and their location.
A Self Organizing Map, clustered with the k-means algorithm, was used for retrieving classes of similar signals in the dataset. The evolution of damage and energy content of each class was followed during the test; this allowed identifying and separating different damage modes.
Moreover, the possibility to apply unsupervised neural network clustering techniques to the AE data is investigated; this is used to filter out the signals which aren’t linkable to a material degradation.
The objective of the study is to identify the damage modes evolving in pultruded glass-fiber reinforced polymers during static tensile tests. The experimental campaign consists of 34 static tensile specimens with two different layups. During each test, Acoustic Emission data is recorded to assess the different characteristics of the signals and their location.
A Self Organizing Map, clustered with the k-means algorithm, was used for retrieving classes of similar signals in the dataset. The evolution of damage and energy content of each class was followed during the test; this allowed identifying and separating different damage modes.
Moreover, the possibility to apply unsupervised neural network clustering techniques to the AE data is investigated; this is used to filter out the signals which aren’t linkable to a material degradation.