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Guillaume Frossard - One of the best experts on this subject based on the ideXlab platform.
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Ply Thickness dependence of the intralaminar fracture in thin Ply carbon epoxy laminates
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract The effect of Ply Thickness t in intralaminar fracture of unidirectional thin-Ply carbon-epoxy laminates is characterized by testing double cantilever beam (DCB) and compact tension (CT) specimens with different t. While the average intralaminar energy release rate (ERR) at initiation is found equal to the corresponding interlaminar values, the steady-state intralaminar ERRs, only reached in the DCB configuration, are approximately three times higher than the corresponding interlaminar values. Due to changes in the extent of bridging, intralaminar steady-state ERRs are ∼30% higher in Thick-Ply (t = 0.150 mm) than in thin-Ply laminates (t = 0.030 mm). Thin-Ply composite laminates exhibit a faster ERR growth with crack length, and for DCB, reach steady-state at a much shorter crack extension than Thick-Ply composites. Traction profiles, due to bridging, are identified using R-curves and implemented in cohesive element simulations to predict intralaminar fracture of DCB and CT specimens. The experimental and simulated load–displacement responses are in good agreement.
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Fracture of thin-Ply composites
2017Co-Authors: Guillaume FrossardAbstract:The demand for carbon/epoxy laminated composites is continuously increasing due to their high specific modulus and strength. Among them, laminates made of particularly thin layers (from t=0.015 to 0.150 mm) and called thin-Ply composites are gaining in interest for the larger design space they offer. Moreover, they have outstanding strength properties, thanks to a significant Ply Thickness effect reflected by a delayed onset of damage. However, the improvement in strength is accompanied by higher brittleness and reduction of fracture toughness. Therefore, this thesis focuses on explanation, characterization, and modeling of Ply Thickness effects on the inter-, intra-, and trans-laminar fracture of M40JB/TP80EP composites in the range t=0.150 to 0.030 mm. In mode I inter- and intra-laminar fracture, while the critical energy release rate (ERR) at initiation is found practically independent of Ply Thickness, it is decreased by 50% (interlaminar) and 23% (intralaminar) at steady-state with decreasing Ply Thickness. During crack growth, fiber bridging develops in the wake of the crack. The heterogeneous microstructure of the Thick-Ply laminates promotes distributed micro-cracking around the crack surface, crack surface waviness and the development of large bundles of bridging fibers, leading to higher fracture resistance. In contrast, the homogeneous microstructure in thin-Ply composites reduces significantly the creation of bridging bundles leading to lower ERR. The results suggest that bridging fibers are better anchored in intra- than inter-laminar fracture due to fiber waviness and misalignment and thus exert larger closing forces that explain the much higher steady-state ERR measured in intra- than in inter-laminar fracture. The translaminar fracture toughness of cross-Ply (CP) and quasi-isotropic (QI) laminates is significantly decreased between t=0.150 and 0.030 mm plies at both the initiation (-70%) and steady-state propagation (-77%). The translaminar fracture toughness scales linearly with Ply Thickness and is found 25% lower in the QI specimens compared to the corresponding CP specimens. Quantitative morphological studies of fracture surfaces show that the Ply Thickness effect is directly correlated to the height of the pull-out fiber bundles, which are much shorter in thinner-Ply specimens. The inter-, intra- and trans-laminar fracture are simulated by cohesive elements models, with linear stiffness degradations corresponding to the initiation ERRs and identified non-linear relations representing the ERRs associated with the toughening mechanisms. In inter- and intra-laminar fracture, these traction-separation relations related to fiber bridging are identified with an efficient R-curve based method developed in this work. In translaminar fracture, the pull-out mechanism is proposed to be modeled by a constant traction level. For each fracture mode, scaling strategies are suggested to account for the Ply Thickness effects. Potential solutions to increase the fracture toughness are investigated. Experimental results demonstrate that the fiber hybridization and interlayer toughening strategies improve the trans- and inter-laminar fracture toughness, respectively, but are accompanied by a decrease in the strength properties. In contrast, the change of fiber/matrix combination (T800/Aero2) offers a simultaneous increase in the toughness and strength properties.
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mode i interlaminar fracture of carbon epoxy laminates effects of Ply Thickness
Composites Part A-applied Science and Manufacturing, 2016Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract In this work, the influence of Ply Thickness on strain energy release rate (ERR) in delamination of carbon-epoxy laminates is addressed. Specimens with three Ply Thicknesses: 0.030, 0.075 and 0.150 mm are tested. While the ERR at onset of crack propagation is independent of Ply Thickness, the plateau level is much lower in thin-Ply laminates than in Thicker Ply ones. This effect is attributed to changes in microstructure, caused by the tow spreading process involved in the fabrication of prepregs. Fiber and matrix rich regions observed only in Thick Ply laminates promote the development of large bundles of bridging fibers which exert large closing forces, leading to higher ERR in Thick-Ply laminates. Fiber bridging distribution is identified using an iterative procedure from R-curve results, and implemented in cohesive element models. This identification method provides reliable results, as the simulated load-displacement curves are in good agreement with experimental results.
J Otsis - One of the best experts on this subject based on the ideXlab platform.
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Ply Thickness dependence of the intralaminar fracture in thin Ply carbon epoxy laminates
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract The effect of Ply Thickness t in intralaminar fracture of unidirectional thin-Ply carbon-epoxy laminates is characterized by testing double cantilever beam (DCB) and compact tension (CT) specimens with different t. While the average intralaminar energy release rate (ERR) at initiation is found equal to the corresponding interlaminar values, the steady-state intralaminar ERRs, only reached in the DCB configuration, are approximately three times higher than the corresponding interlaminar values. Due to changes in the extent of bridging, intralaminar steady-state ERRs are ∼30% higher in Thick-Ply (t = 0.150 mm) than in thin-Ply laminates (t = 0.030 mm). Thin-Ply composite laminates exhibit a faster ERR growth with crack length, and for DCB, reach steady-state at a much shorter crack extension than Thick-Ply composites. Traction profiles, due to bridging, are identified using R-curves and implemented in cohesive element simulations to predict intralaminar fracture of DCB and CT specimens. The experimental and simulated load–displacement responses are in good agreement.
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mode i interlaminar fracture of carbon epoxy laminates effects of Ply Thickness
Composites Part A-applied Science and Manufacturing, 2016Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract In this work, the influence of Ply Thickness on strain energy release rate (ERR) in delamination of carbon-epoxy laminates is addressed. Specimens with three Ply Thicknesses: 0.030, 0.075 and 0.150 mm are tested. While the ERR at onset of crack propagation is independent of Ply Thickness, the plateau level is much lower in thin-Ply laminates than in Thicker Ply ones. This effect is attributed to changes in microstructure, caused by the tow spreading process involved in the fabrication of prepregs. Fiber and matrix rich regions observed only in Thick Ply laminates promote the development of large bundles of bridging fibers which exert large closing forces, leading to higher ERR in Thick-Ply laminates. Fiber bridging distribution is identified using an iterative procedure from R-curve results, and implemented in cohesive element models. This identification method provides reliable results, as the simulated load-displacement curves are in good agreement with experimental results.
Joel Cugnoni - One of the best experts on this subject based on the ideXlab platform.
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Ply Thickness dependence of the intralaminar fracture in thin Ply carbon epoxy laminates
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract The effect of Ply Thickness t in intralaminar fracture of unidirectional thin-Ply carbon-epoxy laminates is characterized by testing double cantilever beam (DCB) and compact tension (CT) specimens with different t. While the average intralaminar energy release rate (ERR) at initiation is found equal to the corresponding interlaminar values, the steady-state intralaminar ERRs, only reached in the DCB configuration, are approximately three times higher than the corresponding interlaminar values. Due to changes in the extent of bridging, intralaminar steady-state ERRs are ∼30% higher in Thick-Ply (t = 0.150 mm) than in thin-Ply laminates (t = 0.030 mm). Thin-Ply composite laminates exhibit a faster ERR growth with crack length, and for DCB, reach steady-state at a much shorter crack extension than Thick-Ply composites. Traction profiles, due to bridging, are identified using R-curves and implemented in cohesive element simulations to predict intralaminar fracture of DCB and CT specimens. The experimental and simulated load–displacement responses are in good agreement.
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mode i interlaminar fracture of carbon epoxy laminates effects of Ply Thickness
Composites Part A-applied Science and Manufacturing, 2016Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract In this work, the influence of Ply Thickness on strain energy release rate (ERR) in delamination of carbon-epoxy laminates is addressed. Specimens with three Ply Thicknesses: 0.030, 0.075 and 0.150 mm are tested. While the ERR at onset of crack propagation is independent of Ply Thickness, the plateau level is much lower in thin-Ply laminates than in Thicker Ply ones. This effect is attributed to changes in microstructure, caused by the tow spreading process involved in the fabrication of prepregs. Fiber and matrix rich regions observed only in Thick Ply laminates promote the development of large bundles of bridging fibers which exert large closing forces, leading to higher ERR in Thick-Ply laminates. Fiber bridging distribution is identified using an iterative procedure from R-curve results, and implemented in cohesive element models. This identification method provides reliable results, as the simulated load-displacement curves are in good agreement with experimental results.
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Thin Ply composites: Experimental characterization and modeling of size-effects
Composites Science and Technology, 2014Co-Authors: R. Amacher, Joel Cugnoni, John Botsis, L. Sorensen, W. Smith, Clemens DransfeldAbstract:Thin-Ply composites are rapidly gaining interest in the composite industry, not only because of the larger design possibilities that they offer, but also because of positive size effects that have been shown to improve performance in various loading conditions [1]. In this work, carbon fiber-epoxy composites of different Ply Thicknesses (30-300 g/m(2) fiber areal weight) were produced from the same batch of Toray M40JB fiber and NorthTPT TP80ep matrix to study the influence of Ply Thickness on the ultimate strength and on the onset of damage in lamina, laminates and components. Uniaxial tension, open-hole compression and open-hole tensile fatigue tests on quasi isotropic [45 degrees/90 degrees/-45 degrees/0 degrees](ns) laminates showed very significant improvements regarding the on-set of damage, and in some cases ultimate strength, when decreasing the Ply Thickness. These performance improvements are the result of major changes in the damage progression and failure modes of the laminates caused by a systematic delay or near suppression of transverse cracking and delamination growth in thin-Ply composites. On the component level, thin-Ply laminates enabled a marked improvement for bolted-joint bearing, especially in hot-wet conditions. Under impact, the 30 mu m thin Ply laminate exhibited a quasi-brittle failure with extensive translaminar cracking while a Ply Thickness of 100 mu m was found as optimum to minimize the projected damage area. Ply Thickness scaling of transverse and in-plane shear strength was identified based on classical laminate theory and unnotched tensile tests on quasi-isotropic specimens. The empirical scaling was found to follow a linear trend over a range of Ply Thicknesses from 30 to 250 mu m. Due to the near suppression of delamination, the strength of thin-Ply composites could then be modeled more effectively than Thick Ply composites using classical laminate theory or standard multilayer shell modeling. (C) 2014 Elsevier Ltd. All rights reserved.
Somen K. Bhudolia - One of the best experts on this subject based on the ideXlab platform.
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Energy Characteristics and Failure Mechanisms for Textile Spread Tow Thin Ply Thermoplastic Composites under Low-velocity Impact
Fibers and Polymers, 2019Co-Authors: Somen K. Bhudolia, Anthony Bert, Goram R. Gohel, Sunil C. Joshi, Makam RaamaAbstract:Carbon composites are deemed suitable for components with complex geometries which require high impact resistance. The broad range of industrial applications requires composite structures to be lighter and not to compromise with their mechanical performance. Non-crimp fabrics with lower fibre areal weight (FAW) are the class of reinforcement material which will only bring the advantages of better mechanical properties but will also offer more longevity to the structures and reduced maintenance costs. This research aims at investigating the low-velocity impact performance of textile spread tow thin Ply (100 gsm) composites with an aim to study the load bearing capability, deflection characteristics and energy characteristics. The results are compared with the baseline Thick (200 gsm) fibre reinforced composites. There was 19.2 %, 16.6 %, and 6.57 % higher peak load for spread tow thin Ply composites when compared to Thick Ply composites at 25 J., 42 J., and 52 J impact energies respectively. Significantly lower residual deflection (40 % to 76 %) and higher major damage energy (20 % to 33 %) were observed for spread tow thin Ply laminates compared to the Thick Ply variant at different impact energies. At 42 J and 52 J impact energies, the damage index (DI) was 2 times and 4 times higher for Thick Ply laminates highlighting extensive damage, which is also observed with detailed failure mechanisms study.
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Experimental and Microscopic Investigation on Mechanical Performance of Textile Spread-tow Thin Ply Composites
Fibers and Polymers, 2019Co-Authors: Somen K. Bhudolia, Sunil Chandrakant Joshi, Yi Di BoonAbstract:Textile non-crimp carbon fabrics (NCCFs) are made of several dry uni-directional (UD) tows which are aligned straight and stitched together. The use of these reduces resin rich areas and stress concentrations that are likely found in woven fabrics composites during manufacturing. The use of spread tows to manufacture the thin plies leads to the fibre areal weight (FAW) of lower than 150 g/m2. This current research aims at investigating the tensile, flexure and interlaminar shear response of thin Ply carbon composites with a view to deduce the failure mechanisms. The baseline comparison is carried out with conventional Thick Ply composites and differences in the failure mechanisms are studied. For tensile tests, reduced number of acoustic emission counts in the case of thin Ply composites indicated that the stresses were unaffected until the laminate ultimate strength. In flexural tests, it was noticed that the resin rich sites near the stitches first initiated compression failure followed by translaminar cracking or longitudinal fibre fracture. This is due to the strong fibre-matrix adhesion in the case of thin Ply composites. No interlaminar shear fracture was seen to occur throughout the laminate Thickness and across the width, leading to a significant improvement in the flexural properties of the thin Ply composites. These thin laminates have better interlaminar shear properties. It was observed through microscopy that thin Ply laminates first undergo interlaminar shear followed by inelastic deformation at the ultimate strength of the material.
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Mode I fracture toughness and fractographic investigation of carbon fibre composites with liquid Methylmethacrylate thermoplastic matrix
Composites Part B-engineering, 2018Co-Authors: Somen K. Bhudolia, Pavel Perrotey, Sunil C. JoshiAbstract:Abstract Laminated polymer composites are extensively used in various applications ranging from aerospace to automotive, building to marine and offshore, and much more. These composites possess higher mechanical properties in their in-plane directions, but lower interlaminar properties. Especially, low interlaminar fracture toughness (ILFT) makes them susceptible to delamination. In the current research, a novel thermoplastic-based thin-Ply composite system is conceptualized and manufactured with an aim to improve the through-the-Thickness properties and which can be a competitive solution to traditional epoxy-based composites as well as other class of thermoplastic composites. The detailed experimental investigation on determining the Mode I ILFT properties of these thin Ply carbon fibre thermoplastic composites, along with thin Ply thermoset composites for benchmarking, is carried out. Quasi-isotropic composite laminates were manufactured using a room temperature cure epoxy, and the novel reactive Methylmethacrylate (MMA) liquid thermoplastic resin. The thin Ply/liquid MMA composites have shown 30% and 72% higher Mode I ILFT properties compared to the Thick Ply/liquid MMA and thin Ply/Epoxy composites respectively. Surface morphological studies were conducted to understand and differentiate damage mechanisms in these composites. From the comprehended damage mechanisms, it was deduced that strong fibre-matrix interface, plastic deformation as well as features like ductile drawings in liquid MMA composites make them more resistant to crack propagation.
Th Gmu - One of the best experts on this subject based on the ideXlab platform.
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Ply Thickness dependence of the intralaminar fracture in thin Ply carbon epoxy laminates
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract The effect of Ply Thickness t in intralaminar fracture of unidirectional thin-Ply carbon-epoxy laminates is characterized by testing double cantilever beam (DCB) and compact tension (CT) specimens with different t. While the average intralaminar energy release rate (ERR) at initiation is found equal to the corresponding interlaminar values, the steady-state intralaminar ERRs, only reached in the DCB configuration, are approximately three times higher than the corresponding interlaminar values. Due to changes in the extent of bridging, intralaminar steady-state ERRs are ∼30% higher in Thick-Ply (t = 0.150 mm) than in thin-Ply laminates (t = 0.030 mm). Thin-Ply composite laminates exhibit a faster ERR growth with crack length, and for DCB, reach steady-state at a much shorter crack extension than Thick-Ply composites. Traction profiles, due to bridging, are identified using R-curves and implemented in cohesive element simulations to predict intralaminar fracture of DCB and CT specimens. The experimental and simulated load–displacement responses are in good agreement.
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mode i interlaminar fracture of carbon epoxy laminates effects of Ply Thickness
Composites Part A-applied Science and Manufacturing, 2016Co-Authors: Guillaume Frossard, Joel Cugnoni, Th Gmu, J OtsisAbstract:Abstract In this work, the influence of Ply Thickness on strain energy release rate (ERR) in delamination of carbon-epoxy laminates is addressed. Specimens with three Ply Thicknesses: 0.030, 0.075 and 0.150 mm are tested. While the ERR at onset of crack propagation is independent of Ply Thickness, the plateau level is much lower in thin-Ply laminates than in Thicker Ply ones. This effect is attributed to changes in microstructure, caused by the tow spreading process involved in the fabrication of prepregs. Fiber and matrix rich regions observed only in Thick Ply laminates promote the development of large bundles of bridging fibers which exert large closing forces, leading to higher ERR in Thick-Ply laminates. Fiber bridging distribution is identified using an iterative procedure from R-curve results, and implemented in cohesive element models. This identification method provides reliable results, as the simulated load-displacement curves are in good agreement with experimental results.