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Costas Galiotis - One of the best experts on this subject based on the ideXlab platform.
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residual Strain and young s modulus determination in cross ply composites using an embedded aramid Fibre Strain sensor
Composites Part A-applied Science and Manufacturing, 1998Co-Authors: B P Arjyal, Costas Galiotis, Stephen L. Ogin, R D WhattinghamAbstract:Abstract The enhancement of Strain in the vicinity of a transverse ply crack in a (0°/90°) s GFRP laminate has been measured with the aid of an aramid Fibre Strain sensor embedded near one 0°/90° interface. This use of a laser Raman microprobe has revealed the Strain profile parallel to the applied load in the 0° ply both very close to the interface and up to a distance of 25 m from the interface. The Strain profiles obtained enable the positions of the cracks to be determined when the laminate is loaded or unloaded, such that local measurements of the residual Strain after cracking and the reduction in Young's modulus as a consequence of cracking can be made.
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monitoring local Strains in cracked cross ply composites using an embedded aramid Fibre Strain sensor
Journal of Materials Science, 1998Co-Authors: B P Arjyal, Costas Galiotis, Stephen L. Ogin, R D WhattinghamAbstract:Single aramid Fibre Strain sensors have been embedded in transparent glass-Fibre reinforced epoxy resin cross-ply laminates. The sensors, located at the 0°/90°/0° ply interfaces, were interrogated by a remote laser Raman microprobe which enabled the changes in the longitudinal Strain in the 0° plies caused by transverse cracking in the 90° ply to be monitored. Strain magnifications of up to about 6 were measured in the crack plane, 10 μm from the 0°/90° ply interface, and it is estimated that the region of enhanced Strain extends to a distance of about 40 μm from the interface. Crack interactions were seen to occur for crack spacings of less than two transverse ply thicknesses.
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Finite element modelling of interfacial failure in model carbon Fibre-epoxy composites
Journal of Materials Science, 1996Co-Authors: R B Nath, D.n. Fenner, Costas GaliotisAbstract:Finite element analysis has been used to model a single unsized carbon Fibre embedded in an epoxy matrix subjected to tensile loading. The predicted Fibre Strain distribution is compared with experimental data, obtained using the technique of laser Raman spectroscopy, for a number of incremental applied Strain levels. Good correlation is obtained on the assumption that the prevailing mode of interfacial failure in the composite involves a conical matrix crack initiating at the Fibre end. The geometry of the matrix crack is estimated on the assumption that the crack propagates in a self-similar manner.
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Measurement of Strain distribution in Fibre reinforced ceramic matrix composites
Composites Part A: Applied Science and Manufacturing, 1996Co-Authors: F. Bollet, Costas Galiotis, Michael J. ReeceAbstract:Abstract The laser Raman microprobe (LRM) is a powerful tool for measuring the Strain fields in composite materials at 1 μm resolution. This technique is applied here to the determination of the Fibre Strain distribution in SiC Fibre/osumilite glass ceramic composites. The effect of experimental parameters, such as laser power upon the results is examined. The application of the LRM for thermal residual Strains determinations and oxidation characterisation, is also outlined.
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Modelling of stress transfer in Fibre composites
Composites Science and Technology, 1994Co-Authors: F.j. Guild, C. Vlattas, Costas GaliotisAbstract:Abstract The finite element analysis method has been used to investigate stress transfer to a single Kevlar Fibre embedded in epoxy resin. Results from the simulations have been compared with experimental results from the technique of Raman spectroscopy; this technique leads to direct measurement of Fibre Strain. The measured Strain profiles can be converted to profiles of interfacial shear stress. The predicted profiles of Fibre Strain and interfacial shear stress are directly comparable to the experimental values; the accuracy of the method of conversion used for the experimental results can be assessed. The predictive model includes elasto-plastic behaviour of the resin; this behaviour is shown to have a critical effect on the transfer of Strain to the Fibre.
Robert J Young - One of the best experts on this subject based on the ideXlab platform.
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Comparing single-walled carbon nanotubes and samarium oxide as Strain sensors for model glass-Fibre/epoxy composites
Composites Science and Technology, 2010Co-Authors: Paweena Sureeyatanapas, Marek Hejda, Stephen J. Eichhorn, Robert J YoungAbstract:Abstract The study of the interfacial stress transfer for glass Fibres in polymer composites through the fragmentation test requires certain assumptions, such as a constant interfacial shear stress. In order to map the local interfacial properties of a composite, both Raman spectroscopy and luminescence spectroscopy have been independently used. Unlike other polymer Fibre composites, the local Strain state of a glass Fibre cannot be obtained using Raman spectroscopy, since only very broad and weak peaks are obtainable. This study shows that when single-walled carbon nanotubes (SWNTs) are added to the silane sizing as a Strain sensor, it becomes possible to map the local Fibre Strain in glass Fibres using Raman spectroscopy. Moreover, if this model glass Fibre contains a small amount of Sm 2 O 3 , as one of the components, luminescence spectroscopy can be simultaneously used to confirm this local Fibre Strain. A combined micromechanical properties study of stress transfer at the Fibre–matrix interface using luminescence spectroscopy, together with Raman spectroscopy, is therefore reported. The local Strain behaviour of both Sm 3+ doped glass and SWNTs in the silane coating are shown to be consistent with a shear-lag model. This indicates that Sm 3+ dopants and SWNTs are excellent sensors for the local deformation of glass Fibre composites.
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Application of raman microscopy to the analysis of high modulus polymer Fibres and composites
British Polymer Journal, 2007Co-Authors: Robert J YoungAbstract:Raman microscopy has been used to study the deformation of carbon Fibres and an experimental grade carbon-Fibre/PEEK composite prepreg. It has been found that the peak position of the Raman-active bands in the Fibres are sensitive to the level of applied Strain. Examination of the peak positions from the carbon Fibres near the surface of the prepreg shows that the Fibres are subjected to a residual compressive Strain. The application of a tensile stress to the composite causes the Fibre Strain to become tensile although significant scatter is found in the measurements. The scatter is thought to be due to variations in the local carbon-Fibre Strain at the 1 μm level. It is demonstrated that residual compressive Strain is expected from differential shrinkage between the Fibres and matrix on cooling the composite from the processing temperature to room temperature.
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micromechanical phenomena during hygrothermal ageing of model composites investigated by raman spectroscopy part i twaron Fibres with different surface treatments
Composites Part A-applied Science and Manufacturing, 2005Co-Authors: A J Cervenka, Robert J Young, K KuesengAbstract:Raman spectroscopy combined with gravimetry has been used to investigate hygrothermal ageing in model composites based on an epoxy resin containing a single filament of a Twaron PPTA Fibre. Three Twaron Fibres have been studied: untreated Fibre (HM), Fibre with a surface finish (HMF) and Fibre with an activated surface (HMA) using two specimen configurations: the diffusion slab (DS) and the double pullout geometry. Time evolutions of the Raman Strain profiles e(x,t) and the water uptake M(t) have been determined for specimens immerse in liquid water and exposed to water vapour. Experimental data are modelled using relationships that describe Fickian diffusion into a solid parallelepiped. Simple micromechanical models have been used to rationalise the Raman Strain profiles in terms of the mid-Fibre Strain e(x=0,t), the dimensionless parameter, n (controlling the stress transfer along interface) and the Fibre Strain energy G(t). For some Fibres and at longer exposure times debonding was observed and the time dependence of the debond length Ld was quantified. Eliminating the exposure time, the swelling behaviour of the matrix is assessed and a concept for determination of the interface fracture energy is proposed. Time dependencies of n, Ld and G(t) are used to rank surface treatments of Twaron Fibres as to durability of their interfaces during hygrothermal ageing.
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micromechanical phenomena during hygrothermal ageing of model composites investigated by raman spectroscopy part ii comparison of the behaviour of pbo and m5 Fibres compared with twaron
Composites Part A-applied Science and Manufacturing, 2005Co-Authors: A J Cervenka, Robert J Young, K KuesengAbstract:Raman spectroscopy combined with gravimetry has been used to investigate hygrothermal aging in model composites based on an epoxy resin containing a single filament of a polymeric Fibre. Two Fibres have been studied—PBO and M5—using two specimen configurations: The diffusion slab (DS) and the double Fibre pull-out (DFPO). Time evolutions of the Raman Strain profiles e(x,t) and the water uptake M(t) have been determined for specimens immersed in liquid water. Simple micromechanical models developed for rationalising data obtained for Twaron are used to process measurements for PBO and M5 (PIPD). In this manner, a direct comparison of the time evolutions of the moisture uptake M(t), mid-Fibre Strain e(x=0,t), the dimensionless Raman shear lag-parameter n and a debond length Ld allows conclusions to be drawn on the aspects of hygrothermal ageing such as durability of a Fibre/matrix interface and Fibre swelling.
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Compressive behaviour of rigid rod polymer Fibres and their adhesion to composite matrixes
Plastics Rubber and Composites, 2003Co-Authors: C. L. So, J.a. Bennett, J. Sirichaisit, Robert J YoungAbstract:AbstractThe deformation behaviour of the new high performance polymer Fibres, poly(p-phenylene benzobisoxazole) (PBO) and polypyridobisimidazole (PIPD) and their adhesion to an epoxy composite matrix have been investigated. Both Fibres give well defined Raman spectra, and the deformation micromechanics of PBO and PIPD single Fibres and composites were studied from stress induced Raman band shifts. Single Fibre stress-Strain curves were determined in both tension and compression, thus providing an estimate of the compressive strength of these Fibres. It was found that the PIPD Fibre has a higher compressive strength (~1 GPa) than PBO (~0·3 GPa) and other high performance polymer Fibres, because hydrogen bond formation is possible between PIPD molecules. It has been shown that when PBO and PIPD Fibres are incorporated into an epoxy resin matrix, the resulting composites show very different interfacial failure mechanisms. The Fibre Strain distribution in the PBO-epoxy composites follows that predicted by the...
P. Clarysse - One of the best experts on this subject based on the ideXlab platform.
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Estimation of In Vivo Myocardial Fibre Strain Using an Architectural Atlas of the Human Heart
2013Co-Authors: C. Casta, Y. Wang V., Y.-m. Zhu, B. R. Cowan, P. Croisille, A. A. Young, P. Nash M., P. ClarysseAbstract:We propose a methodology to estimate 3D+time maps of left ventricular (LV) Fibre Strain from human structural and dynamic MRI data. A biomechanical finite element model integrates Fibre direction throughout the LV extracted from ex vivo human diffusion tensor MRI (DT-MRI) acquisition and motion tracked from tagged MRI (TMRI). This combination enables the estimation of Fibre Strain and its spatio-temporal variation throughout the cardiac cycle. The sensitivity of Fibre Strain estimation on the underlying Fibre orientation is evaluated using a database of 7 DT-MRI and 1 TMRI datasets acquired on normal subjects. Our analysis indicates that the structure of the LV is designed for maximum homogeneity of Fibre Strain during ejection.
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FIMH - Estimation of in vivo myocardial Fibre Strain using an architectural atlas of the human heart
Functional Imaging and Modeling of the Heart, 2013Co-Authors: C. Casta, B. R. Cowan, P. Croisille, A. A. Young, Vicky Y. Wang, Yuemin Zhu, Martyn P. Nash, P. ClarysseAbstract:We propose a methodology to estimate 3D+time maps of left ventricular (LV) Fibre Strain from human structural and dynamic MRI data. A biomechanical finite element model integrates Fibre direction throughout the LV extracted from ex vivo human diffusion tensor MRI (DT-MRI) acquisition and motion tracked from tagged MRI (TMRI). This combination enables the estimation of Fibre Strain and its spatio-temporal variation throughout the cardiac cycle. The sensitivity of Fibre Strain estimation on the underlying Fibre orientation is evaluated using a database of 7 DT-MRI and 1 TMRI datasets acquired on normal subjects. Our analysis indicates that the structure of the LV is designed for maximum homogeneity of Fibre Strain during ejection.
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Estimation of in vivo human myocardial Fibre Strain by integrating diffusion tensor and tagged MRI using FE modelling
2012Co-Authors: Y. Wang V., C. Casta, Y.-m. Zhu, B. R. Cowan, P. Croisille, A. A. Young, P. Clarysse, P. Nash M.Abstract:n this study, we propose a methodology to estimate 3D+time maps of left ventricular Fibre Strain from human structural and dynamic MRI data. A finite element model integrates Fibre principal direction throughout the left ventricle from an ex vivo human diffusion tensor MRI acquisition and motion from tagged MRI. This combination enables the estimation of Fibre Strain and its variation throughout the cardiac cycle. The long-term goal of this study is to apply this technique to an atlas of human Fibre orientations and to investigate the importance of having subject-specific Fibre orientation for Fibre Strain analysis.
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ISBI - Estimation of in vivo human myocardial Fibre Strain by integrating diffusion tensor and tagged MRI using FE modelling
2012 9th IEEE International Symposium on Biomedical Imaging (ISBI), 2012Co-Authors: Vicky Y. Wang, C. Casta, B. R. Cowan, P. Croisille, A. A. Young, P. Clarysse, Yuemin Zhu, Martyn P. NashAbstract:In this study, we propose a methodology to estimate 3D+time maps of left ventricular Fibre Strain from human structural and dynamic MRI data. A finite element model integrates Fibre principal direction throughout the left ventricle from an ex vivo human diffusion tensor MRI acquisition and motion from tagged MRI. This combination enables the estimation of Fibre Strain and its variation throughout the cardiac cycle. The long-term goal of this study is to apply this technique to an atlas of human Fibre orientations and to investigate the importance of having subject-specific Fibre orientation for Fibre Strain analysis.
K Kueseng - One of the best experts on this subject based on the ideXlab platform.
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micromechanical phenomena during hygrothermal ageing of model composites investigated by raman spectroscopy part i twaron Fibres with different surface treatments
Composites Part A-applied Science and Manufacturing, 2005Co-Authors: A J Cervenka, Robert J Young, K KuesengAbstract:Raman spectroscopy combined with gravimetry has been used to investigate hygrothermal ageing in model composites based on an epoxy resin containing a single filament of a Twaron PPTA Fibre. Three Twaron Fibres have been studied: untreated Fibre (HM), Fibre with a surface finish (HMF) and Fibre with an activated surface (HMA) using two specimen configurations: the diffusion slab (DS) and the double pullout geometry. Time evolutions of the Raman Strain profiles e(x,t) and the water uptake M(t) have been determined for specimens immerse in liquid water and exposed to water vapour. Experimental data are modelled using relationships that describe Fickian diffusion into a solid parallelepiped. Simple micromechanical models have been used to rationalise the Raman Strain profiles in terms of the mid-Fibre Strain e(x=0,t), the dimensionless parameter, n (controlling the stress transfer along interface) and the Fibre Strain energy G(t). For some Fibres and at longer exposure times debonding was observed and the time dependence of the debond length Ld was quantified. Eliminating the exposure time, the swelling behaviour of the matrix is assessed and a concept for determination of the interface fracture energy is proposed. Time dependencies of n, Ld and G(t) are used to rank surface treatments of Twaron Fibres as to durability of their interfaces during hygrothermal ageing.
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micromechanical phenomena during hygrothermal ageing of model composites investigated by raman spectroscopy part ii comparison of the behaviour of pbo and m5 Fibres compared with twaron
Composites Part A-applied Science and Manufacturing, 2005Co-Authors: A J Cervenka, Robert J Young, K KuesengAbstract:Raman spectroscopy combined with gravimetry has been used to investigate hygrothermal aging in model composites based on an epoxy resin containing a single filament of a polymeric Fibre. Two Fibres have been studied—PBO and M5—using two specimen configurations: The diffusion slab (DS) and the double Fibre pull-out (DFPO). Time evolutions of the Raman Strain profiles e(x,t) and the water uptake M(t) have been determined for specimens immersed in liquid water. Simple micromechanical models developed for rationalising data obtained for Twaron are used to process measurements for PBO and M5 (PIPD). In this manner, a direct comparison of the time evolutions of the moisture uptake M(t), mid-Fibre Strain e(x=0,t), the dimensionless Raman shear lag-parameter n and a debond length Ld allows conclusions to be drawn on the aspects of hygrothermal ageing such as durability of a Fibre/matrix interface and Fibre swelling.
C. Casta - One of the best experts on this subject based on the ideXlab platform.
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Estimation of In Vivo Myocardial Fibre Strain Using an Architectural Atlas of the Human Heart
2013Co-Authors: C. Casta, Y. Wang V., Y.-m. Zhu, B. R. Cowan, P. Croisille, A. A. Young, P. Nash M., P. ClarysseAbstract:We propose a methodology to estimate 3D+time maps of left ventricular (LV) Fibre Strain from human structural and dynamic MRI data. A biomechanical finite element model integrates Fibre direction throughout the LV extracted from ex vivo human diffusion tensor MRI (DT-MRI) acquisition and motion tracked from tagged MRI (TMRI). This combination enables the estimation of Fibre Strain and its spatio-temporal variation throughout the cardiac cycle. The sensitivity of Fibre Strain estimation on the underlying Fibre orientation is evaluated using a database of 7 DT-MRI and 1 TMRI datasets acquired on normal subjects. Our analysis indicates that the structure of the LV is designed for maximum homogeneity of Fibre Strain during ejection.
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FIMH - Estimation of in vivo myocardial Fibre Strain using an architectural atlas of the human heart
Functional Imaging and Modeling of the Heart, 2013Co-Authors: C. Casta, B. R. Cowan, P. Croisille, A. A. Young, Vicky Y. Wang, Yuemin Zhu, Martyn P. Nash, P. ClarysseAbstract:We propose a methodology to estimate 3D+time maps of left ventricular (LV) Fibre Strain from human structural and dynamic MRI data. A biomechanical finite element model integrates Fibre direction throughout the LV extracted from ex vivo human diffusion tensor MRI (DT-MRI) acquisition and motion tracked from tagged MRI (TMRI). This combination enables the estimation of Fibre Strain and its spatio-temporal variation throughout the cardiac cycle. The sensitivity of Fibre Strain estimation on the underlying Fibre orientation is evaluated using a database of 7 DT-MRI and 1 TMRI datasets acquired on normal subjects. Our analysis indicates that the structure of the LV is designed for maximum homogeneity of Fibre Strain during ejection.
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Estimation of in vivo human myocardial Fibre Strain by integrating diffusion tensor and tagged MRI using FE modelling
2012Co-Authors: Y. Wang V., C. Casta, Y.-m. Zhu, B. R. Cowan, P. Croisille, A. A. Young, P. Clarysse, P. Nash M.Abstract:n this study, we propose a methodology to estimate 3D+time maps of left ventricular Fibre Strain from human structural and dynamic MRI data. A finite element model integrates Fibre principal direction throughout the left ventricle from an ex vivo human diffusion tensor MRI acquisition and motion from tagged MRI. This combination enables the estimation of Fibre Strain and its variation throughout the cardiac cycle. The long-term goal of this study is to apply this technique to an atlas of human Fibre orientations and to investigate the importance of having subject-specific Fibre orientation for Fibre Strain analysis.
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ISBI - Estimation of in vivo human myocardial Fibre Strain by integrating diffusion tensor and tagged MRI using FE modelling
2012 9th IEEE International Symposium on Biomedical Imaging (ISBI), 2012Co-Authors: Vicky Y. Wang, C. Casta, B. R. Cowan, P. Croisille, A. A. Young, P. Clarysse, Yuemin Zhu, Martyn P. NashAbstract:In this study, we propose a methodology to estimate 3D+time maps of left ventricular Fibre Strain from human structural and dynamic MRI data. A finite element model integrates Fibre principal direction throughout the left ventricle from an ex vivo human diffusion tensor MRI acquisition and motion from tagged MRI. This combination enables the estimation of Fibre Strain and its variation throughout the cardiac cycle. The long-term goal of this study is to apply this technique to an atlas of human Fibre orientations and to investigate the importance of having subject-specific Fibre orientation for Fibre Strain analysis.