The Experts below are selected from a list of 3072 Experts worldwide ranked by ideXlab platform
Meisam Jalalvand - One of the best experts on this subject based on the ideXlab platform.
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notch insensitive orientation dispersed pseudo ductile thin ply carbon glass hybrid laminates
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Mohamad Fotouhi, Meisam JalalvandAbstract:Notch sensitivity, free Edge Delamination and brittle failure are limiting factors for the wider use of conventional composite laminates. In our previous study, a hybrid layup concept with the different materials blocked together but with dispersed orientations was successfully used to design pseudo-ductile hybrid composites with no free-Edge Delamination. This study introduces a comprehensive set of designed and characterised orientation-dispersed pseudo-ductile thin-ply hybrid composites to address notch sensitivity, another important limiting factor in conventional composite laminates. Un-notched, open-hole and sharp notched tension tests were performed on three different thin-ply carbon/glass hybrid configurations. The investigated laminates showed a successful pseudo-ductile un-notched behaviour with improved notch-insensitivity and suppression of free-Edge Delamination that was an undesirable damage mode in previously investigated hybrids with plies of the same orientation blocked together. This notch insensitivity results from subcritical damage in the laminates due to the pseudo-ductile damage mechanisms, i.e. dispersed Delamination and fragmentation. These damage mechanisms can eliminate stress concentrations near the notch and suppress the conventional damage mechanisms that govern the notched response of the laminates.
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a novel technique to accurately measure the fibre failure strain in composite laminates under a combined in plane tension and shear stress state
21st International Conference on Composite Materials ICCM 2017, 2017Co-Authors: Meisam Jalalvand, Mohamad Fotouhi, Mun Choong Leong, Michael R WisnomAbstract:A simple and accurate test method is presented to investigate the influence of shear stresses on tensile failure of unidirectional carbon fibre/epoxy. Glass/carbon hybrid laminates are used to eliminate stress concentrations and avoid premature failure at the end-tabs. Free-Edge Delamination is suppressed using thin-plies. Angle-ply carbon/epoxy laminates have been designed to achieve combinations of tensile and shear stresses. It is shown that in-plane shear does not significantly affect the fibre failure strains.
Mohamad Fotouhi - One of the best experts on this subject based on the ideXlab platform.
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notch insensitive orientation dispersed pseudo ductile thin ply carbon glass hybrid laminates
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Mohamad Fotouhi, Meisam JalalvandAbstract:Notch sensitivity, free Edge Delamination and brittle failure are limiting factors for the wider use of conventional composite laminates. In our previous study, a hybrid layup concept with the different materials blocked together but with dispersed orientations was successfully used to design pseudo-ductile hybrid composites with no free-Edge Delamination. This study introduces a comprehensive set of designed and characterised orientation-dispersed pseudo-ductile thin-ply hybrid composites to address notch sensitivity, another important limiting factor in conventional composite laminates. Un-notched, open-hole and sharp notched tension tests were performed on three different thin-ply carbon/glass hybrid configurations. The investigated laminates showed a successful pseudo-ductile un-notched behaviour with improved notch-insensitivity and suppression of free-Edge Delamination that was an undesirable damage mode in previously investigated hybrids with plies of the same orientation blocked together. This notch insensitivity results from subcritical damage in the laminates due to the pseudo-ductile damage mechanisms, i.e. dispersed Delamination and fragmentation. These damage mechanisms can eliminate stress concentrations near the notch and suppress the conventional damage mechanisms that govern the notched response of the laminates.
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a novel technique to accurately measure the fibre failure strain in composite laminates under a combined in plane tension and shear stress state
21st International Conference on Composite Materials ICCM 2017, 2017Co-Authors: Meisam Jalalvand, Mohamad Fotouhi, Mun Choong Leong, Michael R WisnomAbstract:A simple and accurate test method is presented to investigate the influence of shear stresses on tensile failure of unidirectional carbon fibre/epoxy. Glass/carbon hybrid laminates are used to eliminate stress concentrations and avoid premature failure at the end-tabs. Free-Edge Delamination is suppressed using thin-plies. Angle-ply carbon/epoxy laminates have been designed to achieve combinations of tensile and shear stresses. It is shown that in-plane shear does not significantly affect the fibre failure strains.
Joan A. Mayugo - One of the best experts on this subject based on the ideXlab platform.
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damage occurrence at Edges of non crimp fabric thin ply laminates under off axis uniaxial loading
Composites Science and Technology, 2014Co-Authors: G Guillame, Pete Linde, A Turo, J Rena, J. Costa, Joan A. MayugoAbstract:Thin-ply based laminates are a promising development in composite materials and are expected in the near future to outperform conventional laminates in mechanical performance. A rational design with thin plies requires understanding the effect of ply thickness on each damage mechanism. This paper presents an experimental investigation into damage occurrence in a quasi-isotropic laminate made from thin-ply, bi-axial, Non-Crimp-Fabric (NCF), under different off-axis uniaxial loadings. The NCF layers are positioned through the laminate thickness creating two regions, namely THICK and THIN (with and without ply clustering). Then, the onset and progress of three damage mechanisms (transverse matrix cracking, matrix crack induced Delamination and free-Edge Delamination) for both regions are analyzed by monitoring the specimen’s free-Edge. The results show that the critical region where damage occurs is that with ply clustering (THICK), whereas Delamination originating from matrix cracks or free Edge effects are delayed or even suppressed in the THIN region.
G Guillame - One of the best experts on this subject based on the ideXlab platform.
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damage occurrence at Edges of non crimp fabric thin ply laminates under off axis uniaxial loading
Composites Science and Technology, 2014Co-Authors: G Guillame, Pete Linde, A Turo, J Rena, J. Costa, Joan A. MayugoAbstract:Thin-ply based laminates are a promising development in composite materials and are expected in the near future to outperform conventional laminates in mechanical performance. A rational design with thin plies requires understanding the effect of ply thickness on each damage mechanism. This paper presents an experimental investigation into damage occurrence in a quasi-isotropic laminate made from thin-ply, bi-axial, Non-Crimp-Fabric (NCF), under different off-axis uniaxial loadings. The NCF layers are positioned through the laminate thickness creating two regions, namely THICK and THIN (with and without ply clustering). Then, the onset and progress of three damage mechanisms (transverse matrix cracking, matrix crack induced Delamination and free-Edge Delamination) for both regions are analyzed by monitoring the specimen’s free-Edge. The results show that the critical region where damage occurs is that with ply clustering (THICK), whereas Delamination originating from matrix cracks or free Edge effects are delayed or even suppressed in the THIN region.
Michael R Wisnom - One of the best experts on this subject based on the ideXlab platform.
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a novel technique to accurately measure the fibre failure strain in composite laminates under a combined in plane tension and shear stress state
21st International Conference on Composite Materials ICCM 2017, 2017Co-Authors: Meisam Jalalvand, Mohamad Fotouhi, Mun Choong Leong, Michael R WisnomAbstract:A simple and accurate test method is presented to investigate the influence of shear stresses on tensile failure of unidirectional carbon fibre/epoxy. Glass/carbon hybrid laminates are used to eliminate stress concentrations and avoid premature failure at the end-tabs. Free-Edge Delamination is suppressed using thin-plies. Angle-ply carbon/epoxy laminates have been designed to achieve combinations of tensile and shear stresses. It is shown that in-plane shear does not significantly affect the fibre failure strains.
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size effects in unnotched tensile strength of unidirectional and quasi isotropic carbon epoxy composites
Composite Structures, 2008Co-Authors: Michael R Wisnom, B Khan, Stephen R. HallettAbstract:A series of fully scaled tests on unidirectional and quasi-isotropic carbon fibre-epoxy has been carried out. Unidirectional specimens showed a decreasing tensile strength with increasing specimen size, with a reduction of 14% over a factor of 8 change in linear dimension. Quasi-isotropic specimens increased in strength with size when the thickness was changed by repeating the sublaminate stacking sequence, with a 10% increase from a single to four stacked sublaminates. However, strength decreased when the thickness was increased by changing the ply block thickness, with a 62% reduction from 1 to 8 blocked plies. None of the laminates reached the equivalent strength of the unidirectional material, indicating that transverse cracking and Edge Delamination caused premature failure in all cases.
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modelling the interaction between matrix cracks and Delamination damage in scaled quasi isotropic specimens
Composites Science and Technology, 2008Co-Authors: Stephen R. Hallett, W G Jiang, Bijoysri Khan, Michael R WisnomAbstract:A series of tensile tests on scaled quasi-isotropic laminates have been carried out and modelled using finite element analysis to predict failure. Observations during testing and examination of the failed test specimens showed significant influence of matrix cracking and Delamination on the final failure. Initially the virtual crack closure technique (VCCT) was used to determine the applied load that would cause free Edge Delamination. Experimental results showed that failure occurred at loads lower than those predicted. Matrix cracks, observed in the testing, were introduced into the model and interface elements were used to model the Delamination development. This approach gave good correlation to the behaviour observed in the tests. Even in the specimens apparently dominated by fibre failure, Delamination was shown to be significant.
