The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Joris Degrieck - One of the best experts on this subject based on the ideXlab platform.
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on the tension tension fatigue behaviour of a carbon reinforced thermoplastic part ii evaluation of a dumbbell shaped specimen
Polymer Testing, 2011Co-Authors: Ivan De Baere, Christian Hochard, Wim Van Paepegem, Joris DegrieckAbstract:For performing uni-axial fatigue Tests on composite materials, ASTM D3479/D3479M Standard Test Method for Tension–Tension Fatigue of Polymer Matrix Composite Materials is often considered. This Standard prescribes a rectangular shaped specimen with end tabs. However, in part I of this study it became clear that for some materials, such as the carbon PPS under study, the proposed geometry is not ideal for fatigue Tests. In this manuscript, a dumbbell (dogbone) shape is assessed to see whether it performs better under fatigue loading conditions, primarily meaning that failure does not occur in the tabbed section. The shape is first optimised using finite element modelling, after which fatigue experiments are performed. It may be concluded, for the material under study, that the dumbbell shape is preferable to rectangular since failure never occurred under or near the tabbed section, and fatigue life is highly underestimated when using the rectangular specimen.
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modelling the nonlinear shear stress strain response of glass fibre reinforced composites part i experimental results
Composites Science and Technology, 2006Co-Authors: Wim Van Paepegem, Ivan De Baere, Joris DegrieckAbstract:The ASTM D3518/D3518M-94(2001) Standard Test Method for "In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test of a ±45° Laminate" is based on the uniaxial tensile stress-strain response of a ±45° composite laminate which is symmetrically laminated about the midplane. For long glass fibre-reinforced epoxy composites, the Test shows a highly nonlinear shear stress-strain curve. This work is concerned with the development of a material model to predict this mechanical behaviour. Part I discusses the experimental program with tensile Tests on [+45°/-45°]2s laminates and off-axis [10°]8 composites. Cyclic tensile Tests have been performed to assess the amount of permanent shear strain and the residual shear modulus. Part II focuses on the development of the material model and the finite element implementation. Two state variables have been introduced to represent the shear modulus degradation and the accumulation of permanent shear strain. The model has also been applied to the simulation of a three-point bending Test on a [+45°/-45°]2s laminate.
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modelling the nonlinear shear stress strain response of glass fibre reinforced composites part ii model development and finite element simulations
Composites Science and Technology, 2006Co-Authors: W Van Paepegem, I De Baere, Joris DegrieckAbstract:The ASTM D3518/D3518M-94(2001) Standard Test Method for "In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test of a ±45° Laminate" is based on the uniaxial tensile stress-strain response of a ±45° composite laminate which is symmetrically laminated about the midplane. For long glass fibre-reinforced epoxy composites, the Test shows a highly nonlinear shear stress-strain curve. This work is concerned with the development of a material model to predict this mechanical behaviour. Part I discusses the experimental program with tensile Tests on [+45°/-45°]2s laminates and off-axis [10°]8 composites. Cyclic tensile Tests have been performed to assess the amount of permanent shear strain and the residual shear modulus. Part II focuses on the development of the material model and the finite element implementation. Two state variables have been introduced to represent the shear modulus degradation and the accumulation of permanent shear strain. The model has also been applied to the simulation of a three-point bending Test on a [+45°/-45°]2s laminate.
F Puertas - One of the best experts on this subject based on the ideXlab platform.
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the alkali silica reaction in alkali activated granulated slag mortars with reactive aggregate
Cement and Concrete Research, 2002Co-Authors: Ana Fernandezjimenez, F PuertasAbstract:Abstract The expansion of alkali-activated granulated blast furnace slag (AAS) cement mortars with reactive aggregate due to alkali–silica reaction (ASR) was investigated. The alkaline activator used was NaOH solution with 4% Na 2 O (by mass of slag). These results were compared to those of ordinary portland cement (OPC) mortars. The ASTM C1260-94 Standard Test Method based on the NBRI Accelerated Test Method was followed. The nature of the ASR products was also studied by SEM/EDX. The results obtained show that the AAS cement mortars experienced expansion due to the ASR, but expansion occurs at slower rate than with OPC mortars under similar conditions. The cause of the expansion in AAS cement mortars is the formation of sodium and calcium silicate hydrate reaction products with rosette-type morphology. Finally, in order to determine potential expansion due to ASR, the Accelerated Test Method is not suitable for AAS mortars because the reaction rate is initially slow and a longer period of Testing is required.
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the alkali silica reaction in alkali activated granulated slag mortars with reactive aggregate
Cement and Concrete Research, 2002Co-Authors: Ana Fernandezjimenez, F PuertasAbstract:Abstract The expansion of alkali-activated granulated blast furnace slag (AAS) cement mortars with reactive aggregate due to alkali–silica reaction (ASR) was investigated. The alkaline activator used was NaOH solution with 4% Na 2 O (by mass of slag). These results were compared to those of ordinary portland cement (OPC) mortars. The ASTM C1260-94 Standard Test Method based on the NBRI Accelerated Test Method was followed. The nature of the ASR products was also studied by SEM/EDX. The results obtained show that the AAS cement mortars experienced expansion due to the ASR, but expansion occurs at slower rate than with OPC mortars under similar conditions. The cause of the expansion in AAS cement mortars is the formation of sodium and calcium silicate hydrate reaction products with rosette-type morphology. Finally, in order to determine potential expansion due to ASR, the Accelerated Test Method is not suitable for AAS mortars because the reaction rate is initially slow and a longer period of Testing is required.
Wim Van Paepegem - One of the best experts on this subject based on the ideXlab platform.
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on the tension tension fatigue behaviour of a carbon reinforced thermoplastic part ii evaluation of a dumbbell shaped specimen
Polymer Testing, 2011Co-Authors: Ivan De Baere, Christian Hochard, Wim Van Paepegem, Joris DegrieckAbstract:For performing uni-axial fatigue Tests on composite materials, ASTM D3479/D3479M Standard Test Method for Tension–Tension Fatigue of Polymer Matrix Composite Materials is often considered. This Standard prescribes a rectangular shaped specimen with end tabs. However, in part I of this study it became clear that for some materials, such as the carbon PPS under study, the proposed geometry is not ideal for fatigue Tests. In this manuscript, a dumbbell (dogbone) shape is assessed to see whether it performs better under fatigue loading conditions, primarily meaning that failure does not occur in the tabbed section. The shape is first optimised using finite element modelling, after which fatigue experiments are performed. It may be concluded, for the material under study, that the dumbbell shape is preferable to rectangular since failure never occurred under or near the tabbed section, and fatigue life is highly underestimated when using the rectangular specimen.
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modelling the nonlinear shear stress strain response of glass fibre reinforced composites part i experimental results
Composites Science and Technology, 2006Co-Authors: Wim Van Paepegem, Ivan De Baere, Joris DegrieckAbstract:The ASTM D3518/D3518M-94(2001) Standard Test Method for "In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test of a ±45° Laminate" is based on the uniaxial tensile stress-strain response of a ±45° composite laminate which is symmetrically laminated about the midplane. For long glass fibre-reinforced epoxy composites, the Test shows a highly nonlinear shear stress-strain curve. This work is concerned with the development of a material model to predict this mechanical behaviour. Part I discusses the experimental program with tensile Tests on [+45°/-45°]2s laminates and off-axis [10°]8 composites. Cyclic tensile Tests have been performed to assess the amount of permanent shear strain and the residual shear modulus. Part II focuses on the development of the material model and the finite element implementation. Two state variables have been introduced to represent the shear modulus degradation and the accumulation of permanent shear strain. The model has also been applied to the simulation of a three-point bending Test on a [+45°/-45°]2s laminate.
Ivan De Baere - One of the best experts on this subject based on the ideXlab platform.
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on the tension tension fatigue behaviour of a carbon reinforced thermoplastic part ii evaluation of a dumbbell shaped specimen
Polymer Testing, 2011Co-Authors: Ivan De Baere, Christian Hochard, Wim Van Paepegem, Joris DegrieckAbstract:For performing uni-axial fatigue Tests on composite materials, ASTM D3479/D3479M Standard Test Method for Tension–Tension Fatigue of Polymer Matrix Composite Materials is often considered. This Standard prescribes a rectangular shaped specimen with end tabs. However, in part I of this study it became clear that for some materials, such as the carbon PPS under study, the proposed geometry is not ideal for fatigue Tests. In this manuscript, a dumbbell (dogbone) shape is assessed to see whether it performs better under fatigue loading conditions, primarily meaning that failure does not occur in the tabbed section. The shape is first optimised using finite element modelling, after which fatigue experiments are performed. It may be concluded, for the material under study, that the dumbbell shape is preferable to rectangular since failure never occurred under or near the tabbed section, and fatigue life is highly underestimated when using the rectangular specimen.
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modelling the nonlinear shear stress strain response of glass fibre reinforced composites part i experimental results
Composites Science and Technology, 2006Co-Authors: Wim Van Paepegem, Ivan De Baere, Joris DegrieckAbstract:The ASTM D3518/D3518M-94(2001) Standard Test Method for "In-Plane Shear Response of Polymer Matrix Composite Materials by Tensile Test of a ±45° Laminate" is based on the uniaxial tensile stress-strain response of a ±45° composite laminate which is symmetrically laminated about the midplane. For long glass fibre-reinforced epoxy composites, the Test shows a highly nonlinear shear stress-strain curve. This work is concerned with the development of a material model to predict this mechanical behaviour. Part I discusses the experimental program with tensile Tests on [+45°/-45°]2s laminates and off-axis [10°]8 composites. Cyclic tensile Tests have been performed to assess the amount of permanent shear strain and the residual shear modulus. Part II focuses on the development of the material model and the finite element implementation. Two state variables have been introduced to represent the shear modulus degradation and the accumulation of permanent shear strain. The model has also been applied to the simulation of a three-point bending Test on a [+45°/-45°]2s laminate.
Kevin J Folliard - One of the best experts on this subject based on the ideXlab platform.
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the use of the foam index Test to predict air entraining admixture dosage in concrete containing fly ash part iii development of a Standard Test Method proportions of materials
Journal of Astm International, 2008Co-Authors: S. W. Dean, Nathan J Harris, Kenneth C. Hover, Kevin J FolliardAbstract:The foam index Test can be useful for predicting air-entraining admixture (AEA) dosage in concrete or for evaluating AEA interaction with other mixture ingredients. The Test is sensitive to several factors including total water content, water-cementitious materials ratio, ash-cementitious materials ratio, and others. This study isolates several key factors and examines their influence on foam index Test results. Recommendations for a Standard Test are proposed.
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the use of the foam index Test to predict air entraining admixture dosage in concrete containing fly ash part ii development of a Standard Test Method apparatus and procedure
Journal of Astm International, 2008Co-Authors: Nathan J Harris, Kenneth C. Hover, Kevin J FolliardAbstract:The foam index Test can be useful for predicting air-entraining admixture (AEA) dosage in concrete or for evaluating AEA interaction with other mixture ingredients. The Test is sensitive to several factors including container type and fullness, volume of materials, agitation, pipette precision, and others. This study isolates several key factors such as container dimensions and fullness, mixing procedure, time permitted for AEA-cm-water interaction, and time permitted for drainage of unstable foam; and examines their influence on foam index Test results. Recommendations for a Standard Test are proposed.
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the use of the foam index Test to predict aea dosage in concrete containing fly ash part i evaluation of the state of practice
Journal of Astm International, 2008Co-Authors: Nathan J Harris, Kevin J Folliard, Kenneth C. Hover, Tyler M LeyAbstract:Foam index Tests can be used to predict the air-entraining admixtures dosages for concrete containing fly ash. No industry-accepted foam index Test Standard exists and widely different Methods have been used in research and industry. Four foam index Test variants were compared to determine if variations of the Test Method alter the results or change the decisions one makes on the basis of the Test. This is Part I of a three-part series that compares existing foam index Methods, identifies factors to which the Tests are most sensitive, and proposes detailed guidelines for a Standard Test Method.
