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Frank R. Jones - One of the best experts on this subject based on the ideXlab platform.
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The role of matrix cracks and Fibre/matrix debonding on the stress transfer between Fibre and matrix in a single Fibre Fragmentation test
Composites Part A: Applied Science and Manufacturing, 2012Co-Authors: Anbu Clemensis Johnson, Simon A. Hayes, Frank R. JonesAbstract:The single Fibre Fragmentation test is commonly used to characterise the Fibre/matrix interface. During Fragmentation, the stored energy is released resulting in matrix cracking and/or Fibre/matrix debonding. Axisymmetric finite element models were formulated to study the impact of matrix cracks and Fibre/matrix debonding on the effective stress transfer efficiency (EST) and stress transfer length (STL). At high strains, plastic deformation in the matrix dominated the stress transfer mechanism. The combination of matrix cracking and plasticity reduced the EST and increased STL. For experimental validation, three resins were formulated and the Fragmentation of an unsized and uncoupled E-glass Fibre examined as a function of matrix properties. Fibre failure was always accompanied by matrix cracking and debonding. With the stiff resin, debonding, transverse matrix cracking and conical crack initiation were observed. With a lower modulus and lower yield strength resin the transverse matrix crack length decreased while that of the conical crack increased.
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Data reduction methodologies for single Fibre Fragmentation test: Role of the interface and interphase
Composites Part A: Applied Science and Manufacturing, 2009Co-Authors: Anbu Clemensis Johnson, Simon A. Hayes, Frank R. JonesAbstract:Abstract The single Fibre Fragmentation test (SFFT) is commonly used to characterise the Fibre/matrix adhesion. In order to quantify the Fibre/matrix adhesion the cumulative stress transfer function (CSTF) methodology was developed so that the elastoplasticity of the matrix could be included in the analysis through the plasticity-effect model [Tripathi D, Chen F, Jones FR. A comprehensive model to predict the stress fields in a single Fibre composite. J Comp Mater 1996;30;1514–38., Tripathi D, Jones FR. Measurement of the load-bearing capability of the Fibre/matrix interface by single Fibre Fragmentation. Comp Sci Technol 1997;57:925–35.] The limitations of this technique for the data reduction have been addressed by the use of the Plasticity Model to input the non-linearity of the matrix into methodology for Fragmentation of a Fibre in a matrix. An improved methodology, known as the revised cumulative stress transfer function (RCSTF) is described. The adhesion of a nanoscale plasma copolymer coated glass/epoxy system has been used to examine this approach to the Fragmentation process. This methodology is also extended to account for the presence of an interphase. To validate the three phase model, carbon Fibre coated with high and medium modulus epoxy resin were used to simulate Fibre/interphase/matrix.
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Stress transfer function for interface assessment in composites with plasma copolymer functionalized carbon Fibres
The Journal of Adhesion, 2002Co-Authors: N. Lopattananon, Simon A. Hayes, Frank R. JonesAbstract:Radio-frequency-induced plasma copolymerization of acrylic acid/1,7-octadiene was used to produce a range of functionalized plasma copolymer coatings with controlled degree of adhesion. The single-Fibre Fragmentation test was used to characterize the adhesion of plasma copolymer coated Fibres to epoxy resin. The cumulative stress transfer function (CSTF) and Kelly-Tyson approaches were used to evaluate the degree of adhesion. By continuous monitoring of the Fragmentation process, it was found that the mechanical performance of a composite material could be evaluated using the CSTF methodology at strain well below saturation. The degree of debonding was a good measure of relative interface/interphase adhesive strength. The trend in the CSTF is consistent with the propagation of interfacial debonds during the test. For a completely debonded Fibre a normalized CSTF value, referred as stress transfer efficiency (STE), was found to provide a more consistent analysis that was able to differentiate between Fibre...
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Evaluation of micromechanical properties of advanced polymer composites
Plastics Rubber and Composites, 2001Co-Authors: A. Abu Bakar, Frank R. JonesAbstract:Abstract A new methodology for the prediction of stress transfer in the single Fibre Fragmentation test, known as the plasticity effect model, has been used. A new data reduction technique, known as the cumulative stress transfer function (CSTF technique), which takes the dierent damage events observed during the Fragmentation test into account, was used to obtain a measure of Fibre–matrix adhesion from the Fragmentation test. The effect of carbon Fibre surface treatment on the interface of microcomposite properties was studied using the CSTF technique. It was found that the CSTF technique could predict Fibre–matrix adhesion in a single Fibre Fragmentation test more accurately than the conventional data reduction technique. In this study, a commercial resin system was used to produce Fragmentation test specimens.
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A technological solution to the testing and data reduction of single Fibre Fragmentation tests
Composites Part A: Applied Science and Manufacturing, 1998Co-Authors: Devesh Tripathi, N. Lopattananon, Frank R. JonesAbstract:Abstract The single Fibre Fragmentation test was first introduced in 1965 for measuring interfacial adhesion in Fibre reinforced composites. However, this test is still far from a routine test and no suitable testing standard exists. Consequently, this method is hardly used by research laboratories of the reinforcing Fibre manufacturers, composite fabricators and other standardisation organisations. The main reasons for the failure of the Fragmentation test to establish as a standard quality control tool are the time consuming manual testing procedures and the poor confidence in the data reduction techniques used for calculating the interfacial adhesion parameter. An integrated machine, software and data reduction approach has been developed for the Fragmentation test. The new approach allows the stoppage of the Fragmentation test at pre-defined strains and digitisation of the whole embedded Fibre length using a microscope attached with a video-camera and Sun work-station. Subsequently, the fragment and associated debond lengths are measured using a Visual Basic program in a semi-automatic process. The problems associated with the huge amount of computer graphics data and compatibility of different graphics formats have been sorted out. This leads to substantial savings in the time required for the Fragmentation test. Using this integrated machine and software approach, the single Fibre Fragmentation test has been carried out on carbon Fibre samples with well-defined interfaces. The results were analysed using the conventional Kelly–Tyson model and the cumulative stress transfer function (CSTF) technique, at different applied strains. It has been shown that the CSTF technique can be used for assessing the Fibre-matrix adhesion from the single Fibre Fragmentation test at any applied strain before or after the saturation of the Fragmentation process, thus eliminating the need for specially formulated resin for the Fragmentation test.
F R Jones - One of the best experts on this subject based on the ideXlab platform.
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the role of matrix cracks and Fibre matrix debonding on the stress transfer between Fibre and matrix in a single Fibre Fragmentation test
Composites Part A-applied Science and Manufacturing, 2012Co-Authors: Anbu Clemensis Johnson, S A Hayes, F R JonesAbstract:The single Fibre Fragmentation test is commonly used to characterise the Fibre/matrix interface. During Fragmentation, the stored energy is released resulting in matrix cracking and/or Fibre/matrix debonding. Axisymmetric finite element models were formulated to study the impact of matrix cracks and Fibre/matrix debonding on the effective stress transfer efficiency (EST) and stress transfer length (STL). At high strains, plastic deformation in the matrix dominated the stress transfer mechanism. The combination of matrix cracking and plasticity reduced the EST and increased STL. For experimental validation, three resins were formulated and the Fragmentation of an unsized and uncoupled E-glass Fibre examined as a function of matrix properties. Fibre failure was always accompanied by matrix cracking and debonding. With the stiff resin, debonding, transverse matrix cracking and conical crack initiation were observed. With a lower modulus and lower yield strength resin the transverse matrix crack length decreased while that of the conical crack increased.
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Single Fibre Fragmentation test for assessing adhesion in Fibre reinforced composites
Journal of Materials Science, 1998Co-Authors: D. Tripathi, F R JonesAbstract:The single Fibre Fragmentation test for measuring the properties of the Fibre–matrix interface in Fibre-reinforced composites is reviewed. Special emphasis has been paid to the recent stress transfer models in single Fibre composites and its application to the development of a suitable data reduction technique for the Fragmentation test. The complexities of the correlation of the micromechanical results to the properties of the macrocomposites have been highlighted.
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measurement of the load bearing capability of the Fibre matrix interface by single Fibre Fragmentation
Composites Science and Technology, 1997Co-Authors: Devesh Tripathi, F R JonesAbstract:Abstract The Fragmentation test is now commonly used for measuring the Fibre/matrix adhesion in a singlefilament polymer composite. The limitations of the current data-reduction techniques used to calculate the value of interfacial shear strength from the Fragmentation data are identified. Recently, we have proposed the plasticity-effect model to predict the stress profile in a composite containing a single discontinuous Fibre. This model can also be further used to predict the stress fields in a single-short-Fibre composite where debonding occurs at the Fibre/matrix interface. In this paper, the plasticity-effect model is further developed to propose a new data-reduction technique for the Fragmentation test. In this method, the interfacial shear stress and the tensile stress in the individual fragments are predicted from the plasticity-effect model and the total tensile stress transferred to all of the Fibre fragments at a particular matrix strain is calculated. The total tensile stress transferred to all of the Fibre fragments normalised against the Fibre length is defined as the cumulative stress-transfer function (CSTF). The Fibre/matrix adhesion can be predicted by assuming that a better interface is able to transfer more load to the reinforcing Fibre, which is reflected in a higher CSTF value. A glass-Fibre/epoxy system with different coupling agents is used for the validation of this technique.
Jang Kyo Kim - One of the best experts on this subject based on the ideXlab platform.
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strain sensitive raman spectroscopy and electrical resistance of carbon nanotube coated glass Fibre sensors
Composites Science and Technology, 2012Co-Authors: Li Liu, Shafi Ullah Khan, Jang Kyo KimAbstract:Abstract This paper presents the development of glass Fibres coated with nanocomposites consisting of carbon nanotubes (CNTs) and epoxy. Single glass Fibres with different CNT content coating are embedded in a polymer matrix as a strain sensor for composite structures. Raman spectroscopy and electrical response of glass Fibres under mechanical load are coupled for in situ sensing of deformation in composites. The results show that the Fibres with nanocomposite coating exhibit efficient stress transfer across the Fibre/matrix interface, and these with a higher CNT content are more prone to Fibre Fragmentation at the same matrix strain. A relationship between the Fibre stress and the change in electrical resistance against the Fibre strain is established. The major finding of this study has a practical implication in that the Fibres with nanocomposite coating can serve as a sensor to monitor the deformation and damage process in composites.
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Stress transfer in the Fibre Fragmentation test: Part III Effects of interface debonding and matrix yielding
Journal of Materials Science, 1997Co-Authors: Jang Kyo KimAbstract:The micromechanics of stress transfer is presented for the Fibre Fragmentation test of microcomposites containing debonded Fibre–matrix interface and yielded matrix at the interface region. Results from the parametric study are discussed for carbon Fibre composites containing epoxy and polyetheretherketone (PEEK) matrices, representing respectively typical brittle debonding and matrix yielding behaviour at the interface region. The stress transfer phenomena are characterized for the two interface failure processes. The sequence of interface failure and Fibre fracture as a function of applied stress are also identified. Maximum debonded and yielded interface lengths are obtained above which a Fibre will fracture into smaller lengths. There are also threshold Fibre fragment lengths above which Fibre will fracture without interface debonding or matrix yielding. The applied stresses for these conditions are governed by three strength properties of the composite constituents, namely interface shear bond strength, matrix shear yield strength and Fibre tensile strength for given elastic constants of the Fibre and matrix, and the geometric factors of the microcomposite. The ineffective length, a measure of the efficiency of stress transfer across the Fibre–matrix interface, is shown to strongly depend on the extent to which these failure mechanisms take place at the interface region.
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Fracture Mechanics Analysis of the Fibre Fragmentation Test
Journal of Composite Materials, 1995Co-Authors: Li Min Zhou, Jang Kyo Kim, Caroline Baillie, Yiu-wing MaiAbstract:An improved micromechanics analysis is developed for the stress transfer in the single Fibre Fragmentation test. Considering the partially debonded interface as the most general case, Griffith's fracture mechanics approach is employed to derive a debond criterion at the Fibre-matrix interface. An average Fibre strength model from the Weibull statistics is used to determine the mean Fibre fragment length as a function of applied stress. A parametric study for a carbon Fibre-epoxy matrix composite shows that there is a critical applied stress below which no interfacial debonding takes place. The Poisson effect increases the interface shear stress at the debonded region towards the Fibre ends, which in turn discourages further debond propagation. The mean Fibre fragment length is the sum of the bonded and debonded lengths, and is substantially smaller for the composite containing Fibres with a higher surface treatment level at a given applied stress greater than the critical level.
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Stress transfer in the Fibre Fragmentation test: Part I An improved analysis based on a shear strength criterion
Journal of Materials Science, 1993Co-Authors: Jang Kyo Kim, Li Min Zhou, Yiu-wing MaiAbstract:An improved micromechanics model has been developed of the stress transfer for a single Fibre embedded in a matrix subjected to uniaxial loading. Debond crack growth is analysed based on the shear strength criterion such that when the interfacial shear stress reaches the shear bond strength, debonding occurs; and the average strength concept based on Weibull statistics is considered for Fibre Fragmentation. The influences of the interfacial shear bond strength and the Fibre strength on the stress distributions in the composite constituents are evaluated (...)
Yiu-wing Mai - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Fibre tensile strength and Fibre/matrix adhesion using single Fibre Fragmentation tests
Composites Part A: Applied Science and Manufacturing, 1998Co-Authors: Shiqiang Deng, Yiu-wing Mai, Hong-yuan LiuAbstract:Abstract Single Fibre Fragmentation tests were conducted to obtain a comprehensive understanding of the Fibre Fragmentation phenomenon in several carbon Fibre/epoxy composite systems. Fibre tensile strength and Fibre/matrix interfacial adhesion were evaluated, and some important experimental aspects associated with the evaluation of the test results were addressed. Fibre Fragmentation in a matrix is a complex process with many factors interacting with each other, which influence the Fibre Fragmentation behaviour and, as a result, complicate the evaluation of the Fibre/matrix interfacial properties. The failure modes of carbon Fibres in epoxy resins were also greatly influenced by the variations of these factors. Without considering the special mechanisms of the Fibre Fragmentation behaviour for individual Fibre/matrix systems, equivocal results may be obtained by simply adopting certain micromechanics model to define interfacial parameters.
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evaluation of Fibre tensile strength and Fibre matrix adhesion using single Fibre Fragmentation tests
Composites Part A-applied Science and Manufacturing, 1998Co-Authors: Shiqiang Deng, Yiu-wing Mai, Hong-yuan LiuAbstract:Abstract Single Fibre Fragmentation tests were conducted to obtain a comprehensive understanding of the Fibre Fragmentation phenomenon in several carbon Fibre/epoxy composite systems. Fibre tensile strength and Fibre/matrix interfacial adhesion were evaluated, and some important experimental aspects associated with the evaluation of the test results were addressed. Fibre Fragmentation in a matrix is a complex process with many factors interacting with each other, which influence the Fibre Fragmentation behaviour and, as a result, complicate the evaluation of the Fibre/matrix interfacial properties. The failure modes of carbon Fibres in epoxy resins were also greatly influenced by the variations of these factors. Without considering the special mechanisms of the Fibre Fragmentation behaviour for individual Fibre/matrix systems, equivocal results may be obtained by simply adopting certain micromechanics model to define interfacial parameters.
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An appraisal of composite interface mechanics models and some challenging problems
Composite Interfaces, 1998Co-Authors: Hong-yuan Liu, Yiu-wing MaiAbstract:A critical review of previous mechanics models proposed for the evaluation of interfacial properties from single Fibre tests is presented with regard to their applicability and limitations. New results which include the effects of some important factors, such as pre-existing Fibre flaws. thermal residual stresses and matrix cracks. are provided for a single Fibre Fragmentation test. By comparing the stress distributions of single Fibre fragment and multi-Fibre fragment, a basic method to study the multi-Fibre composite is introduced in order to relate the interfacial parameters to the mechanical properties of the bulk composite. Some challenging problems on Fibre-matrix interfaces are discussed for future research work.
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stress transfer in the Fibre Fragmentation test part iii effect of matrix cracking and interface debonding
Journal of Materials Science, 1997Co-Authors: Hong-yuan Liu, Yiu-wing Mai, Li Min ZhouAbstract:A theoretical stress analysis has been developed for the Fibre Fragmentation test in the presence of matrix cracks at sites of Fibre breaks. The strain energy release rates for both matrix cracking and interface debonding are calculated for a carbon Fibre/epoxy matrix composite. By comparing these strain energy release rates with the corresponding specific fracture resistances, the competition between matrix crack growth and interface debonding has been studied. The distributions of Fibre axial stress and interfacial shear stress obtained from the present analysis show that the matrix crack substantially reduces the efficiency of stress transfer from the matrix to the Fibre.
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Fracture Mechanics Analysis of the Fibre Fragmentation Test
Journal of Composite Materials, 1995Co-Authors: Li Min Zhou, Jang Kyo Kim, Caroline Baillie, Yiu-wing MaiAbstract:An improved micromechanics analysis is developed for the stress transfer in the single Fibre Fragmentation test. Considering the partially debonded interface as the most general case, Griffith's fracture mechanics approach is employed to derive a debond criterion at the Fibre-matrix interface. An average Fibre strength model from the Weibull statistics is used to determine the mean Fibre fragment length as a function of applied stress. A parametric study for a carbon Fibre-epoxy matrix composite shows that there is a critical applied stress below which no interfacial debonding takes place. The Poisson effect increases the interface shear stress at the debonded region towards the Fibre ends, which in turn discourages further debond propagation. The mean Fibre fragment length is the sum of the bonded and debonded lengths, and is substantially smaller for the composite containing Fibres with a higher surface treatment level at a given applied stress greater than the critical level.
Hong-yuan Liu - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of Fibre tensile strength and Fibre/matrix adhesion using single Fibre Fragmentation tests
Composites Part A: Applied Science and Manufacturing, 1998Co-Authors: Shiqiang Deng, Yiu-wing Mai, Hong-yuan LiuAbstract:Abstract Single Fibre Fragmentation tests were conducted to obtain a comprehensive understanding of the Fibre Fragmentation phenomenon in several carbon Fibre/epoxy composite systems. Fibre tensile strength and Fibre/matrix interfacial adhesion were evaluated, and some important experimental aspects associated with the evaluation of the test results were addressed. Fibre Fragmentation in a matrix is a complex process with many factors interacting with each other, which influence the Fibre Fragmentation behaviour and, as a result, complicate the evaluation of the Fibre/matrix interfacial properties. The failure modes of carbon Fibres in epoxy resins were also greatly influenced by the variations of these factors. Without considering the special mechanisms of the Fibre Fragmentation behaviour for individual Fibre/matrix systems, equivocal results may be obtained by simply adopting certain micromechanics model to define interfacial parameters.
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evaluation of Fibre tensile strength and Fibre matrix adhesion using single Fibre Fragmentation tests
Composites Part A-applied Science and Manufacturing, 1998Co-Authors: Shiqiang Deng, Yiu-wing Mai, Hong-yuan LiuAbstract:Abstract Single Fibre Fragmentation tests were conducted to obtain a comprehensive understanding of the Fibre Fragmentation phenomenon in several carbon Fibre/epoxy composite systems. Fibre tensile strength and Fibre/matrix interfacial adhesion were evaluated, and some important experimental aspects associated with the evaluation of the test results were addressed. Fibre Fragmentation in a matrix is a complex process with many factors interacting with each other, which influence the Fibre Fragmentation behaviour and, as a result, complicate the evaluation of the Fibre/matrix interfacial properties. The failure modes of carbon Fibres in epoxy resins were also greatly influenced by the variations of these factors. Without considering the special mechanisms of the Fibre Fragmentation behaviour for individual Fibre/matrix systems, equivocal results may be obtained by simply adopting certain micromechanics model to define interfacial parameters.
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An appraisal of composite interface mechanics models and some challenging problems
Composite Interfaces, 1998Co-Authors: Hong-yuan Liu, Yiu-wing MaiAbstract:A critical review of previous mechanics models proposed for the evaluation of interfacial properties from single Fibre tests is presented with regard to their applicability and limitations. New results which include the effects of some important factors, such as pre-existing Fibre flaws. thermal residual stresses and matrix cracks. are provided for a single Fibre Fragmentation test. By comparing the stress distributions of single Fibre fragment and multi-Fibre fragment, a basic method to study the multi-Fibre composite is introduced in order to relate the interfacial parameters to the mechanical properties of the bulk composite. Some challenging problems on Fibre-matrix interfaces are discussed for future research work.
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stress transfer in the Fibre Fragmentation test part iii effect of matrix cracking and interface debonding
Journal of Materials Science, 1997Co-Authors: Hong-yuan Liu, Yiu-wing Mai, Li Min ZhouAbstract:A theoretical stress analysis has been developed for the Fibre Fragmentation test in the presence of matrix cracks at sites of Fibre breaks. The strain energy release rates for both matrix cracking and interface debonding are calculated for a carbon Fibre/epoxy matrix composite. By comparing these strain energy release rates with the corresponding specific fracture resistances, the competition between matrix crack growth and interface debonding has been studied. The distributions of Fibre axial stress and interfacial shear stress obtained from the present analysis show that the matrix crack substantially reduces the efficiency of stress transfer from the matrix to the Fibre.