The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform
Subbareddy Daggumati - One of the best experts on this subject based on the ideXlab platform.
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fatigue and post fatigue stress strain analysis of a 5 harness Satin Weave carbon fibre reinforced composite
Composites Science and Technology, 2013Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, I De Baere, Ignace VerpoesAbstract:Abstract This paper presents the experimental fatigue damage analysis of a carbon-PPS (PolyPhenylene Sulphide) 5-harness Satin Weave composite under tension–tension fatigue. Evolution of the longitudinal strain as well as the longitudinal stiffness of the composite specimen was monitored throughout the cyclic load process. During the fatigue test, instrumentation of the composite structural response is categorized into two parts: (i) the first priority was to monitor the macro-scale structural response such as the increase in the longitudinal strain and hence decrease in the composite longitudinal stiffness; (ii) the second priority was to capture the micro-scale damage events which are occurring in correlation with the observed fluctuations in the macro-scale structural response. Finally, comparison of the strength as well as stress–strain behaviour of the virgin composite samples to the fatigue tested specimens gives an overview of the effect of the induced fatigue damage on the strength and stiffness of the composite specimen.
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Local Strain In A 5 - Harness Satin Weave Composite Under Static Tension: Part Ii - Meso-Fe Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Tomas Praet, Benedict Verhegghe, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents the local strain analysis in a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load using meso-FE simulations. In order to predict the local strain profiles as observed in the experiments (Part I) at various locations of the composite, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Apart from the calculation of local strain values at different locations (inside / traction free surface) of the composite laminate, the aim of the numerical simulations is to understand the 'shadowing' effects of the internal ply shifting on the surface strain behaviour of a 5-harness Satin Weave composite. Comparison of the experimental local strain values (Part I) at various locations of the Satin Weave composite reveals that the effects of local yarn constraints are negligible on the local longitudinal strain behavior of the composite. However, local stress-strain profiles obtained from unit cell meso-FE simulations indicate that the longitudinal strain and the transverse stress distribution in the weft yarn at the yarn crimp location is sensitive to the unit cell stacking as well as to the applied boundary conditions to the unit cell.
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Local Strain In A 5-Harness Satin Weave Composite Under Static Tension: Part I - Experimental Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Eli Voet, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents an experimental method for determining the local strain distribution in the plies of a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load. In contrast to unidirectional composites, the yarn interlacing pattern in textile composites causes heterogeneous strain fields with large strain gradients around the yarn crimp regions. In addition, depending on the local constraints that are imposed by the surrounding plies, the deformation behaviour of the laminate inner layers may vary from that of the surface layers, which are relatively more free to deform, compared to the inner layers. In order to validate the above hypothesis, the local strains on the composite surface were measured using digital image correlation technique (LIMESS). Internal strains in the composite laminate were measured using embedded Fibre Optic Sensors (FOS). Based on the DIC results, the strain profiles at various locations on the composite surface were estimated. Using the FOS results, the maximum and minimum strain values in the laminate inner layers were evaluated. Comparison of the local strain values at different laminate positions provides an estimate of the influence of the adjacent layers on the local longitudinal strain behaviour of a Satin Weave composite. Part II of this paper elucidates the local strain variation computed using the meso-FE simulations. In addition to the comparison of numerical and experimental strain profiles, Part II presents the maximum and minimum strain envelopes for the carbon-PPS (PolyPhenelyne Sulphide) thermoplastic 5-harness Satin Weave composite.
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local strain variation in the plies of a Satin Weave composite experimental vs numerical
Photomechanics : International conference on full-field measurement techniques and their applications in experimental solid mechanics Abstracts, 2011Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Eli Voe, Tomas Prae, Enedic Verhegghe, Ignace VerpoesAbstract:Along with the advantages of multi directional load carrying capabilities, the complicated interlacing pattern of the yarns in a textile composite produce large stress – strain gradients. The stress-strain behavior in a textile composite is influenced by: a) stacking sequence; b) number of plies in the laminate; c) distance of the ply to the surface [1]. From the numerical perspective, the investigation of the free edge and free surface effects in a textile composite unit cell [2] reveals that the local stress behavior changes considerably depending upon the finite/ infinite conditions used for the unit cell FE analysis. In the above context, to capture the variation in local parameters such as strain and damage profiles at different locations (inside/surface) of the Satin Weave composite under the tensile load, experimental techniques such as strain mapping, Fibre Brag Grating sensors (FBG’s) and the microscopic analysis is used. For the numerical validation, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Comparison of the numerical and experimental results (Table 1) provides valuable information regarding the local strain variation (from edge to the centre) in a Satin Weave composite (Figure 1). In the similar guide lines, local damage variation is also studied using different unit cell stacks.
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local damage in a 5 harness Satin Weave composite under static tension part i experimental analysis
Composites Science and Technology, 2010Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, I De Baere, Ignaas VerpoesAbstract:Abstract This paper presents an experimental damage analysis of a 5-harness Satin Weave carbon–PPS (polyphenylene sulphide) composite under uni-axial static tensile load. In order to understand the local damage behaviour, tensile tests were performed and accompanied by acoustic emission (AE) and microscopic analysis of the composite specimen. These tests enable us to detect the damage initiation stress as well as the damage initiation location in the composite. Microscopic observation of the tested composite laminates allowed the characterization of the sequence of intra-yarn transverse damage (perpendicular to the load direction) occurrence at different locations in the laminate, starting from crack initiation to the final failure of the composite. The earliest crack events occurred inside the laminate middle layers, followed by the damage on the traction free surface. It is observed that the initiation of the transverse crack, the location of the crack in the weft yarn cross-section (centre/near the edges) is affected by the relative position of the ply in the laminate (local nesting configuration). The first part of this paper deals with the experimental characterization of sequential damage in a 5-harness Satin Weave composite. Part II deals with the meso-FE modeling of damage using a Satin Weave unit cell, and the correlation between experimental and numerical results.
Joris Degrieck - One of the best experts on this subject based on the ideXlab platform.
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thermal strain effects in thermoplastic Satin Weave composite laminates
16th European Conference on composite material Proceedings, 2014Co-Authors: Eli Voe, Wim Van Paepegem, Gee Luyck, Joris DegrieckAbstract:In this research, thermoplastic carbon-PPS woven fabrics are subjected to temperature cycles from -20 °C till 160 °C. All samples have embedded fibre Bragg gratings in the symmetryplane of the laminates. It will be shown that heating above the Tg reverses more or less the thermal residual strains and that after cool-down the spectral response of the fibre Bragg gratings has changed, proving the annealing effect. Although macroscopically the two different lay-ups are identical, the results show that thermal strain in the symmetry plane is significantly influenced by the composite’s stacking sequence.
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fatigue and post fatigue stress strain analysis of a 5 harness Satin Weave carbon fibre reinforced composite
Composites Science and Technology, 2013Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, I De Baere, Ignace VerpoesAbstract:Abstract This paper presents the experimental fatigue damage analysis of a carbon-PPS (PolyPhenylene Sulphide) 5-harness Satin Weave composite under tension–tension fatigue. Evolution of the longitudinal strain as well as the longitudinal stiffness of the composite specimen was monitored throughout the cyclic load process. During the fatigue test, instrumentation of the composite structural response is categorized into two parts: (i) the first priority was to monitor the macro-scale structural response such as the increase in the longitudinal strain and hence decrease in the composite longitudinal stiffness; (ii) the second priority was to capture the micro-scale damage events which are occurring in correlation with the observed fluctuations in the macro-scale structural response. Finally, comparison of the strength as well as stress–strain behaviour of the virgin composite samples to the fatigue tested specimens gives an overview of the effect of the induced fatigue damage on the strength and stiffness of the composite specimen.
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Local Strain In A 5 - Harness Satin Weave Composite Under Static Tension: Part Ii - Meso-Fe Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Tomas Praet, Benedict Verhegghe, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents the local strain analysis in a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load using meso-FE simulations. In order to predict the local strain profiles as observed in the experiments (Part I) at various locations of the composite, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Apart from the calculation of local strain values at different locations (inside / traction free surface) of the composite laminate, the aim of the numerical simulations is to understand the 'shadowing' effects of the internal ply shifting on the surface strain behaviour of a 5-harness Satin Weave composite. Comparison of the experimental local strain values (Part I) at various locations of the Satin Weave composite reveals that the effects of local yarn constraints are negligible on the local longitudinal strain behavior of the composite. However, local stress-strain profiles obtained from unit cell meso-FE simulations indicate that the longitudinal strain and the transverse stress distribution in the weft yarn at the yarn crimp location is sensitive to the unit cell stacking as well as to the applied boundary conditions to the unit cell.
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Local Strain In A 5-Harness Satin Weave Composite Under Static Tension: Part I - Experimental Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Eli Voet, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents an experimental method for determining the local strain distribution in the plies of a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load. In contrast to unidirectional composites, the yarn interlacing pattern in textile composites causes heterogeneous strain fields with large strain gradients around the yarn crimp regions. In addition, depending on the local constraints that are imposed by the surrounding plies, the deformation behaviour of the laminate inner layers may vary from that of the surface layers, which are relatively more free to deform, compared to the inner layers. In order to validate the above hypothesis, the local strains on the composite surface were measured using digital image correlation technique (LIMESS). Internal strains in the composite laminate were measured using embedded Fibre Optic Sensors (FOS). Based on the DIC results, the strain profiles at various locations on the composite surface were estimated. Using the FOS results, the maximum and minimum strain values in the laminate inner layers were evaluated. Comparison of the local strain values at different laminate positions provides an estimate of the influence of the adjacent layers on the local longitudinal strain behaviour of a Satin Weave composite. Part II of this paper elucidates the local strain variation computed using the meso-FE simulations. In addition to the comparison of numerical and experimental strain profiles, Part II presents the maximum and minimum strain envelopes for the carbon-PPS (PolyPhenelyne Sulphide) thermoplastic 5-harness Satin Weave composite.
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evaluation of the transversal strain state in a Satin Weave composite using fibre bragg gratings
Proceedings of SPIE the International Society for Optical Engineering, 2011Co-Authors: Eli Voe, Joris Degrieck, Gee Luyck, Wim Van PaepegemAbstract:Satin woven composites can be seen as a series of connected unit cells with a definite length and width. Along the length and width of one unit cell, local strain fields can vary significantly due to the yarn interlacing pattern. Embedded Type I FBGs with a 80 μm- and 125 μm cladding diameter are used to study the internal transversal strain variations in unloaded and tensile loaded thermo-plastic 5-harness Satin Weave composite test specimens. The residual strains are examined at different (axial) load levels up to 300MPa and 1.2million cycles. Differential transversal strains up to 0.07% are presented. Results show that the embedded FBGs are capable of measuring long term the transversal strain distributions. It is found that the yarn interlacing pattern of the Satin Weave composite causes complex and random local strain fields during loading and that, even though axial strain measurements are matching very well with external strain measurements, a large scatter exists in local transversal strain states between the different composite test-coupons.
Wim Van Paepegem - One of the best experts on this subject based on the ideXlab platform.
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thermal strain effects in thermoplastic Satin Weave composite laminates
16th European Conference on composite material Proceedings, 2014Co-Authors: Eli Voe, Wim Van Paepegem, Gee Luyck, Joris DegrieckAbstract:In this research, thermoplastic carbon-PPS woven fabrics are subjected to temperature cycles from -20 °C till 160 °C. All samples have embedded fibre Bragg gratings in the symmetryplane of the laminates. It will be shown that heating above the Tg reverses more or less the thermal residual strains and that after cool-down the spectral response of the fibre Bragg gratings has changed, proving the annealing effect. Although macroscopically the two different lay-ups are identical, the results show that thermal strain in the symmetry plane is significantly influenced by the composite’s stacking sequence.
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fatigue and post fatigue stress strain analysis of a 5 harness Satin Weave carbon fibre reinforced composite
Composites Science and Technology, 2013Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, I De Baere, Ignace VerpoesAbstract:Abstract This paper presents the experimental fatigue damage analysis of a carbon-PPS (PolyPhenylene Sulphide) 5-harness Satin Weave composite under tension–tension fatigue. Evolution of the longitudinal strain as well as the longitudinal stiffness of the composite specimen was monitored throughout the cyclic load process. During the fatigue test, instrumentation of the composite structural response is categorized into two parts: (i) the first priority was to monitor the macro-scale structural response such as the increase in the longitudinal strain and hence decrease in the composite longitudinal stiffness; (ii) the second priority was to capture the micro-scale damage events which are occurring in correlation with the observed fluctuations in the macro-scale structural response. Finally, comparison of the strength as well as stress–strain behaviour of the virgin composite samples to the fatigue tested specimens gives an overview of the effect of the induced fatigue damage on the strength and stiffness of the composite specimen.
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Local Strain In A 5 - Harness Satin Weave Composite Under Static Tension: Part Ii - Meso-Fe Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Tomas Praet, Benedict Verhegghe, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents the local strain analysis in a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load using meso-FE simulations. In order to predict the local strain profiles as observed in the experiments (Part I) at various locations of the composite, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Apart from the calculation of local strain values at different locations (inside / traction free surface) of the composite laminate, the aim of the numerical simulations is to understand the 'shadowing' effects of the internal ply shifting on the surface strain behaviour of a 5-harness Satin Weave composite. Comparison of the experimental local strain values (Part I) at various locations of the Satin Weave composite reveals that the effects of local yarn constraints are negligible on the local longitudinal strain behavior of the composite. However, local stress-strain profiles obtained from unit cell meso-FE simulations indicate that the longitudinal strain and the transverse stress distribution in the weft yarn at the yarn crimp location is sensitive to the unit cell stacking as well as to the applied boundary conditions to the unit cell.
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Local Strain In A 5-Harness Satin Weave Composite Under Static Tension: Part I - Experimental Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Eli Voet, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents an experimental method for determining the local strain distribution in the plies of a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load. In contrast to unidirectional composites, the yarn interlacing pattern in textile composites causes heterogeneous strain fields with large strain gradients around the yarn crimp regions. In addition, depending on the local constraints that are imposed by the surrounding plies, the deformation behaviour of the laminate inner layers may vary from that of the surface layers, which are relatively more free to deform, compared to the inner layers. In order to validate the above hypothesis, the local strains on the composite surface were measured using digital image correlation technique (LIMESS). Internal strains in the composite laminate were measured using embedded Fibre Optic Sensors (FOS). Based on the DIC results, the strain profiles at various locations on the composite surface were estimated. Using the FOS results, the maximum and minimum strain values in the laminate inner layers were evaluated. Comparison of the local strain values at different laminate positions provides an estimate of the influence of the adjacent layers on the local longitudinal strain behaviour of a Satin Weave composite. Part II of this paper elucidates the local strain variation computed using the meso-FE simulations. In addition to the comparison of numerical and experimental strain profiles, Part II presents the maximum and minimum strain envelopes for the carbon-PPS (PolyPhenelyne Sulphide) thermoplastic 5-harness Satin Weave composite.
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evaluation of the transversal strain state in a Satin Weave composite using fibre bragg gratings
Proceedings of SPIE the International Society for Optical Engineering, 2011Co-Authors: Eli Voe, Joris Degrieck, Gee Luyck, Wim Van PaepegemAbstract:Satin woven composites can be seen as a series of connected unit cells with a definite length and width. Along the length and width of one unit cell, local strain fields can vary significantly due to the yarn interlacing pattern. Embedded Type I FBGs with a 80 μm- and 125 μm cladding diameter are used to study the internal transversal strain variations in unloaded and tensile loaded thermo-plastic 5-harness Satin Weave composite test specimens. The residual strains are examined at different (axial) load levels up to 300MPa and 1.2million cycles. Differential transversal strains up to 0.07% are presented. Results show that the embedded FBGs are capable of measuring long term the transversal strain distributions. It is found that the yarn interlacing pattern of the Satin Weave composite causes complex and random local strain fields during loading and that, even though axial strain measurements are matching very well with external strain measurements, a large scatter exists in local transversal strain states between the different composite test-coupons.
Stepan Vladimirovitch Lomov - One of the best experts on this subject based on the ideXlab platform.
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fatigue and post fatigue stress strain analysis of a 5 harness Satin Weave carbon fibre reinforced composite
Composites Science and Technology, 2013Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, I De Baere, Ignace VerpoesAbstract:Abstract This paper presents the experimental fatigue damage analysis of a carbon-PPS (PolyPhenylene Sulphide) 5-harness Satin Weave composite under tension–tension fatigue. Evolution of the longitudinal strain as well as the longitudinal stiffness of the composite specimen was monitored throughout the cyclic load process. During the fatigue test, instrumentation of the composite structural response is categorized into two parts: (i) the first priority was to monitor the macro-scale structural response such as the increase in the longitudinal strain and hence decrease in the composite longitudinal stiffness; (ii) the second priority was to capture the micro-scale damage events which are occurring in correlation with the observed fluctuations in the macro-scale structural response. Finally, comparison of the strength as well as stress–strain behaviour of the virgin composite samples to the fatigue tested specimens gives an overview of the effect of the induced fatigue damage on the strength and stiffness of the composite specimen.
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Local Strain In A 5 - Harness Satin Weave Composite Under Static Tension: Part Ii - Meso-Fe Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Tomas Praet, Benedict Verhegghe, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents the local strain analysis in a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load using meso-FE simulations. In order to predict the local strain profiles as observed in the experiments (Part I) at various locations of the composite, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Apart from the calculation of local strain values at different locations (inside / traction free surface) of the composite laminate, the aim of the numerical simulations is to understand the 'shadowing' effects of the internal ply shifting on the surface strain behaviour of a 5-harness Satin Weave composite. Comparison of the experimental local strain values (Part I) at various locations of the Satin Weave composite reveals that the effects of local yarn constraints are negligible on the local longitudinal strain behavior of the composite. However, local stress-strain profiles obtained from unit cell meso-FE simulations indicate that the longitudinal strain and the transverse stress distribution in the weft yarn at the yarn crimp location is sensitive to the unit cell stacking as well as to the applied boundary conditions to the unit cell.
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Local Strain In A 5-Harness Satin Weave Composite Under Static Tension: Part I - Experimental Analysis
Composites Science and Technology, 2011Co-Authors: Subbareddy Daggumati, J.-y. Xu, Eli Voet, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignaas VerpoestAbstract:This paper presents an experimental method for determining the local strain distribution in the plies of a thermoplastic 5-harness Satin Weave composite under uni-axial static tensile load. In contrast to unidirectional composites, the yarn interlacing pattern in textile composites causes heterogeneous strain fields with large strain gradients around the yarn crimp regions. In addition, depending on the local constraints that are imposed by the surrounding plies, the deformation behaviour of the laminate inner layers may vary from that of the surface layers, which are relatively more free to deform, compared to the inner layers. In order to validate the above hypothesis, the local strains on the composite surface were measured using digital image correlation technique (LIMESS). Internal strains in the composite laminate were measured using embedded Fibre Optic Sensors (FOS). Based on the DIC results, the strain profiles at various locations on the composite surface were estimated. Using the FOS results, the maximum and minimum strain values in the laminate inner layers were evaluated. Comparison of the local strain values at different laminate positions provides an estimate of the influence of the adjacent layers on the local longitudinal strain behaviour of a Satin Weave composite. Part II of this paper elucidates the local strain variation computed using the meso-FE simulations. In addition to the comparison of numerical and experimental strain profiles, Part II presents the maximum and minimum strain envelopes for the carbon-PPS (PolyPhenelyne Sulphide) thermoplastic 5-harness Satin Weave composite.
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local strain variation in the plies of a Satin Weave composite experimental vs numerical
Photomechanics : International conference on full-field measurement techniques and their applications in experimental solid mechanics Abstracts, 2011Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Eli Voe, Tomas Prae, Enedic Verhegghe, Ignace VerpoesAbstract:Along with the advantages of multi directional load carrying capabilities, the complicated interlacing pattern of the yarns in a textile composite produce large stress – strain gradients. The stress-strain behavior in a textile composite is influenced by: a) stacking sequence; b) number of plies in the laminate; c) distance of the ply to the surface [1]. From the numerical perspective, the investigation of the free edge and free surface effects in a textile composite unit cell [2] reveals that the local stress behavior changes considerably depending upon the finite/ infinite conditions used for the unit cell FE analysis. In the above context, to capture the variation in local parameters such as strain and damage profiles at different locations (inside/surface) of the Satin Weave composite under the tensile load, experimental techniques such as strain mapping, Fibre Brag Grating sensors (FBG’s) and the microscopic analysis is used. For the numerical validation, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Comparison of the numerical and experimental results (Table 1) provides valuable information regarding the local strain variation (from edge to the centre) in a Satin Weave composite (Figure 1). In the similar guide lines, local damage variation is also studied using different unit cell stacks.
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local damage in a 5 harness Satin Weave composite under static tension part i experimental analysis
Composites Science and Technology, 2010Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, I De Baere, Ignaas VerpoesAbstract:Abstract This paper presents an experimental damage analysis of a 5-harness Satin Weave carbon–PPS (polyphenylene sulphide) composite under uni-axial static tensile load. In order to understand the local damage behaviour, tensile tests were performed and accompanied by acoustic emission (AE) and microscopic analysis of the composite specimen. These tests enable us to detect the damage initiation stress as well as the damage initiation location in the composite. Microscopic observation of the tested composite laminates allowed the characterization of the sequence of intra-yarn transverse damage (perpendicular to the load direction) occurrence at different locations in the laminate, starting from crack initiation to the final failure of the composite. The earliest crack events occurred inside the laminate middle layers, followed by the damage on the traction free surface. It is observed that the initiation of the transverse crack, the location of the crack in the weft yarn cross-section (centre/near the edges) is affected by the relative position of the ply in the laminate (local nesting configuration). The first part of this paper deals with the experimental characterization of sequential damage in a 5-harness Satin Weave composite. Part II deals with the meso-FE modeling of damage using a Satin Weave unit cell, and the correlation between experimental and numerical results.
Ignace Verpoes - One of the best experts on this subject based on the ideXlab platform.
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fatigue and post fatigue stress strain analysis of a 5 harness Satin Weave carbon fibre reinforced composite
Composites Science and Technology, 2013Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, I De Baere, Ignace VerpoesAbstract:Abstract This paper presents the experimental fatigue damage analysis of a carbon-PPS (PolyPhenylene Sulphide) 5-harness Satin Weave composite under tension–tension fatigue. Evolution of the longitudinal strain as well as the longitudinal stiffness of the composite specimen was monitored throughout the cyclic load process. During the fatigue test, instrumentation of the composite structural response is categorized into two parts: (i) the first priority was to monitor the macro-scale structural response such as the increase in the longitudinal strain and hence decrease in the composite longitudinal stiffness; (ii) the second priority was to capture the micro-scale damage events which are occurring in correlation with the observed fluctuations in the macro-scale structural response. Finally, comparison of the strength as well as stress–strain behaviour of the virgin composite samples to the fatigue tested specimens gives an overview of the effect of the induced fatigue damage on the strength and stiffness of the composite specimen.
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local strain variation in the plies of a Satin Weave composite experimental vs numerical
Photomechanics : International conference on full-field measurement techniques and their applications in experimental solid mechanics Abstracts, 2011Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Eli Voe, Tomas Prae, Enedic Verhegghe, Ignace VerpoesAbstract:Along with the advantages of multi directional load carrying capabilities, the complicated interlacing pattern of the yarns in a textile composite produce large stress – strain gradients. The stress-strain behavior in a textile composite is influenced by: a) stacking sequence; b) number of plies in the laminate; c) distance of the ply to the surface [1]. From the numerical perspective, the investigation of the free edge and free surface effects in a textile composite unit cell [2] reveals that the local stress behavior changes considerably depending upon the finite/ infinite conditions used for the unit cell FE analysis. In the above context, to capture the variation in local parameters such as strain and damage profiles at different locations (inside/surface) of the Satin Weave composite under the tensile load, experimental techniques such as strain mapping, Fibre Brag Grating sensors (FBG’s) and the microscopic analysis is used. For the numerical validation, different unit cell stacking models with appropriate boundary conditions are used for the FE analysis. Comparison of the numerical and experimental results (Table 1) provides valuable information regarding the local strain variation (from edge to the centre) in a Satin Weave composite (Figure 1). In the similar guide lines, local damage variation is also studied using different unit cell stacks.
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local damage in a 5 harness Satin Weave composite under static tension part ii meso fe modelling
Composites Science and Technology, 2010Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Ignace VerpoesAbstract:This study forms the second part of a paper on the local damage analysis in a thermo-plastic 5-harness Satin Weave composite under uni-axial static tensile load. The experimental observations of Part I are confronted with the meso-FE simulations. Part II describes the following steps regarding the unit cell meso-FE modelling starting from: (1) construction of the unit cell geometrical model; (2) estimation of the homogenized elastic constants of the unit cell using different boundary conditions; (3) evaluation of the local stress and damage behavior of the unit cell using meso-FE simulations. The aim of the numerical analysis is to investigate the dependency of local ply stress and damage profiles on the adjacent layers of the laminate. In order to reflect the constraints posed by the surrounding plies, depending on the ply placement in the laminate (inside/surface), different unit cell geometrical models with suitable boundary conditions were used for the FE analysis. From the numerical simulations it is observed that: (a) the homogenized elastic constants of the unit cell vary considerably depending on the boundary conditions used for the unit cell FE analysis; (b) intra-yarn stress and damage profiles are sensitive to the unit cell model as well as the boundary conditions used for the FE analysis.
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evaluation of local strain profiles in a Satin Weave composite experimental vs meso fe modelling
14th European conference on Composite Materials (ECCM-14), 2010Co-Authors: Subbareddy Daggumati, Joris Degrieck, Stepan Vladimirovitch Lomov, Wim Van Paepegem, Eli Voe, Tomas Prae, Enedic Verhegghe, Ignace VerpoesAbstract:In order to determine the strain distribution in the plies of a thermo-plastic 5-harness Satin Weave composite, a comprehensive experimental and numerical analysis is conducted under uni-axial static tensile load. In textile composites, depending on the local constraints posed by surrounding plies, the out-of-plane deformation behavior of a yarn crimp in the laminate inner layers is different from that of surface layers, which are relatively more free to deform compared to the inner layers. The above mentioned difference in deformation behaviour of various plies may cause the difference in the local strain behaviour for a chosen ply in the laminate. In order to validate the above hypothesis, local strain distribution on the laminate surface is quantified using digital image correlation technique. Internal strains in the composite laminate were measured using embedded fibre optic sensors. Finally, unit cell meso-FE analysis provided the substantial evidence to understand the effect of internal yarn shifting on the local strain behavior of the 5-harness Satin Weave composite.
