Abstract Interleaving heavy micro-fibre veils, commonly used to improve interlaminar fracture toughness, severely compromises tensile and compressive properties. To reduce the trade-off, this study interleaved two different types of light (4 g/m2) co-polyamide veils into a thin-ply quasi-isotropic baseline laminate. Sub-micron resolution X-ray micro-computed tomography provided insight into the after-manufacturing state of the veil fibres as well as into the fracture process zone of mode-I interlaminar fracture toughness specimens. The veil fibre diameter was the key parameter in determining the tensile properties (the veil with thinner fibres avoided resin accumulation at the interfaces and left the baseline properties unaffected). Both veils decreased the compressive strength by up to 9%. Mode-I crack propagation was controlled by the adhesion between the veil fibres and resin. Veils fibres with the higher adhesion deflected crack propagation to the surrounding 0 ° plies, which improved mode-I initiation and propagation interlaminar fracture toughness (by 101 % and 43 % ).
Last. Josep Costa(University of Girona)H-Index: 49
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Abstract Thin-ply composite laminates are currently receiving researchers’ attention due to their specific advantages in delaying or even suppressing some damage mechanisms such as matrix cracks. Lower load capacity during impact event is one of the main factors against thin-ply laminates use. This paper presents novel thin-ply laminate design with improved damage resistance and load capacity. First, the effect of mismatch angle on damage resistance and damage mechanisms occurring during an impa...
#1Chunfang Huang(National University of Defense Technology)H-Index: 3
#2Su Ju(National University of Defense Technology)H-Index: 9
Last. Dazhi Jiang(National University of Defense Technology)H-Index: 15
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Abstract Composite thin-ply laminates have been reported to exhibit superior performance in various loading conditions than standard-ply laminates due to positive size effects. However, the ultimate tensile strength of the thin-ply ( 0.125 mm) or standard-ply (0.125 mm) laminates with same size of the hole. Besides, fracture morphologies showed a transition from a combined mode of matrix crack, delamination and pull-out at 45° and −45° ply in the thick and standard-ply laminates to a quasi-britt...
#1Joël Cugnoni(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
#2R. Amacher(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 4
Last. John Botsis(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
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Abstract Thin-ply composites represent a promising approach to further improve the performance of carbon fibre composite structures thanks to their ability to delay the onset of matrix cracking and delamination up to the point of fibre dominated failure. However, this increased strength comes with a more brittle failure response which raises concerns on damage tolerance. Thus a careful material optimization is needed to address this trade-off. In this work, eight different formulations of thin-p...
Abstract While thin-plies delay the onset of matrix cracking and improve certain in-plane mechanical properties, the effect they have on the out-of-plane response remains unclear. We compared the impact resistance, tolerance and sequence of failure events of thin laminates manufactured with thin- or standard-ply non-crimp fabrics (fibre areal weight of 67 and 134 gsm per ply). Damage initiation and propagation was detailed using (a) quasi-static indentation and impact tests at incremental energy...
#2Reed Kopp(MIT: Massachusetts Institute of Technology)H-Index: 3
Last. Brian L. Wardle(MIT: Massachusetts Institute of Technology)H-Index: 43
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Thin-ply carbon fiber laminates have exhibited superior mechanical properties and damage resistance when compared to standard thickness plies and enable greater flexibility in laminate design. However, the increased ply count in thin-ply laminates also increases the number of ply-ply interfaces, thereby increasing the number of relatively weak and delamination-prone interlaminar regions. In this study, we report the first experimental realization of aligned carbon nanotube interlaminar reinforce...
#2Metin Tanoğlu(İzmir Institute of Technology)H-Index: 23
Last. Engin Aktaş(İzmir Institute of Technology)H-Index: 8
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Abstract In this study, carbon fiber/epoxy (CF/EP) composites were interleaved with polyamide-6,6 (PA 66) nonwoven veils at two different areal weight densities (17 and 50 gsm) to improve their delamination resistance against Mode-I loading. Mode-I fracture toughness (DCB), tensile, open hole tensile (OHT), flexural, compression, short beam shear (ILSS) and Charpy-impact tests were performed on the reference and PA 66 interleaved composite specimens. The DCB test results showed that the initiati...
#1Guillaume Frossard(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 3
#2Joël Cugnoni(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 26
Last. John Botsis(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
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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 ...
New generation non-crimp fabric (NCF) offers an attractive thin and lightweight building block alternative in the design of composite materials and structures. Pre-assembly of multiple plies of parallel fibers, each laying in a different orientation would not require crimping of the fibers and would enable one-axis lay-up that can substantially reduce the labor, scrap, and manufacturing costs. A state-of-the-art tow-spreading technique enables ply thickness to be reduced to as low as one-third o...
Abstract To improve the damage resistance and tolerance of thin laminates manufactured with thin-ply non-crimp-fabrics, we interleaved non-woven veils into the interlaminar regions (two different types of co-polyamide veil were studied). We devised a low velocity impact and compression after impact (CAI) experimental campaign, where quasi-static indentation (QSI) tests at increasing loading displacements gave insight into the damage initiation and growth. For impact and QSI, the damage area was ...
Abstract This study analyses the damage tolerance of nanofibre interleaved composites when subjected to low velocity impact. Cross-ply glass/epoxy composite laminates are produced. Drop-weight impact and residual compressive strength measurements are performed on these laminates according to the ASTM D7136 and ASTM D7137 standards for a range of impact energies around the Barely Visible Impact Damage energy limit. Polyamide 6, polyamide 6.9 and polycaprolactone nanofibrous veils with two differe...
Abstract null null null In this study, a multiscale cellulose fiber interlayer consisting of chopped flax fibers (FFs) and cellulose nanofiber (CNFs) was proposed for enhancing the interlaminar fracture toughness of carbon fiber/epoxy composites. The cellulose fiber interlayer was treated by waterborne epoxy to improve the interfacial compatibility with the epoxy matrix. The end-notched flexure results showed that the addition of the cellulose fiber interlayer in the carbon fiber/epoxy composite...
Abstract Adhesive bonding is one of the most suitable joining technologies in terms of weight and mechanical performance for current carbon fiber reinforced polymer aircraft fuselage structures. However, traditional joint topologies such as single overlap joints induce high peel stresses, resulting in sudden failure and low joint strength when compared to metal adherends. This drawback in using carbon fiber reinforced polymer is hindering their performance and efficiency in full-scale structures...
Carbon fiber reinforced thermosetting polyimide (CF/TSPI) composites were interleaved with thermally stable thermoplastic polyimide (TPPI) fiber veils in order to improve the interlaminar fracture toughness without sacrificing the heat resistance. Both of the mode I and mode II interlaminar fracture toughness (GIC and GIIC) for the untoughened laminate and TPPI fiber veils interleaved laminates were characterized by the double cantilever beam (DCB) test and end notch flexure (ENF) test, respecti...
Last. K.B. Katnam(University of Manchester)H-Index: 17
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Abstract This study investigates the influence of thermoplastic non-woven veils on the interlaminar fracture energy and toughening mechanisms under mode-I dominant loading conditions in out-of-autoclave resin-infused carbon fibre-epoxy laminates. Two different non-woven micro-fibre veils, Polyetherimide (PEI) and Polyphenylene Sulfide (PPS), of low areal weight (∼10 g/m2) are introduced between carbon fibre non-crimp fabric (NCF) laminae prior to vacuum assisted resin infusion (with a low viscou...
#1Jalal Nasser(UM: University of Michigan)H-Index: 7
#2Lisha Zhang(UM: University of Michigan)H-Index: 7
Last. Henry A. Sodano(UM: University of Michigan)H-Index: 53
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Abstract Delamination is a persistant problem that restricts the ability of carbon fiber reinforced composites to support out-of-plane loading. One method to alleviate this issue which has shown promise in recent years is the use of nanoscale interleaves to strengthen the interlaminar region of carbon fiber composites. Here, layers of aramid nanofibers (ANFs) are deposited onto the surface of woven carbon fabric using a spray-coating technique that avoids agglomeration issues and improves the in...
#1Yunsen Hu(UWA: University of Western Australia)H-Index: 6
#2Fei Cheng(China University of Geosciences)H-Index: 4
Last. Xiaozhi Hu(UWA: University of Western Australia)H-Index: 38
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Abstract Flexural properties of carbon fibre reinforced plastics (CFRPs) with multi-layer interfacial reinforcement of hierarchically structured aramid pulp (AP) fibres were measured at −40 and −100 °C under three-point bending (3 PB) together with unreinforced CFRPs. After curing, the ‘interleaf’ thicknesses were 3.3, 5.6 and 12.2 μm for three different AP areal densities of 0.8, 1.6 and 3.2 g/m2, respectively. 3 PB tests of control and AP reinforced CFRPs were also performed at 20 °C to compar...
#2Metin Tanoğlu(İzmir Institute of Technology)H-Index: 23
Last. Engin Aktaş(İzmir Institute of Technology)H-Index: 8
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Thermoplastic interleaving is a promising technique to improve delamination resistance of laminated composites. In this study, plain-weave carbon fiber/epoxy composites were interleaved with nylon ...
