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.
Abstract Failure of a ply due to transverse loading is one of the mechanisms that was taken into account in physically-based failure criteria, used in composites design. However, experimental data are scarce and the measurement techniques used in the past are time consuming and involve a lot of specimen handling during testing. While some physical information is currently well consolidated (such as the dependence of the strength on ply thickness, or in situ strength), there still remain relevant...
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 laye...
Abstract This paper presents an experimental investigation of the mechanical response of a new class of advanced composite materials manufactured using thin non-crimp fabrics. Tensile and compressive tests in both unnotched and notched specimens were performed using two different lay-ups. The notched tests were based on specimens with central cracks and with circular holes, loaded in tension and compression. Digital image correlation was used to monitor the onset and propagation of damage on the...
Abstract A comprehensive review of techniques for the experimental characterisation of the fracture toughness associated with the translaminar (fibre-breaking) failure modes of continuously reinforced laminated composites is presented. The collection of work relating to tensile failure reveals a varied approach in terms of specimen configuration, size and data reduction, despite the existence of an ASTM standard. Best practices are identified and suggestions for extending the scope of the curren...
Last. Shantanu Bhowmik(TU Delft: Delft University of Technology)H-Index: 14
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Abstract Multi-wall carbon nanotube (MWNT) added carbon fiber reinforced plastics (CFRP) and thin-ply composites are suggested as solutions to improve resistance against low earth orbit (LEO) environment and mechanical properties. Accelerated ground simulation experiments were performed for CFRP, MWNT reinforced CFRP, thin-ply CFRP and MWNT reinforced thin-ply CFRP. The used ground simulation facility can simulate high vacuum, atomic oxygen, ultraviolet (UV) light and thermal cycling simultaneou...
#2Akiko Kuroda(UTokyo: University of Tokyo)H-Index: 2
Last. Takahira Aoki(UTokyo: University of Tokyo)H-Index: 16
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Composite laminates with thin-ply layers are expected to exhibit superior damage resistance to the standard composite laminates. This study investigated the damage characteristics of carbon fiber/toughened epoxy thin-ply laminates subjected to transverse loadings. Quasi-isotropic laminates were prepared using both standard prepregs and thin-ply prepregs in order to examine the effect of ply thickness on the damage accumulation processes. Clear difference on damage accumulation process between st...
A program of scaled tests on unnotched and open-hole tension and compression specimens is summarized. Quasi-isotropic IM7/8552 carbon-fiber epoxy specimens have been tested using two different scaling techniques: sub-laminate-level ([45/90/ - 45/0]ns) and ply-level scaling ([45n/90 n/ - 45n/0n]s), independently varying the thickness and in-plane dimensions. Significant scaling effects are shown, with both strength and failure mechanisms changing with specimen size and the thickness scaling metho...
Large fibre reinforced composite structures can give much lower strengths than small test specimens, so a proper understanding of scaling is vital for their safe and efficient use. Small size (scale) specimens are commonly tested to justify allowable stresses, but could be dangerous if results are extrapolated without accounting for scaling effects. On the other hand large factors are sometimes applied to compensate for uncertainties, resulting in overweight designs. The most important variables...
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 decreas...
#1Tomohiro Yokozeki(JAXA: Japan Aerospace Exploration Agency)H-Index: 28
#2Yuichiro Aoki(JAXA: Japan Aerospace Exploration Agency)H-Index: 10
Last. Toshio Ogasawara(JAXA: Japan Aerospace Exploration Agency)H-Index: 29
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Composite laminates manufactured from thin-ply prepregs are expected to have superior damage resistance properties compared to those from standard prepregs. Although the use of thin-ply prepregs leads to increase in manufacturing cost, the damage resistance properties against matrix cracking and delamination increase. This study investigates several strength properties as well as the damage resistance properties of carbon fiber/toughened epoxy composite laminates for the applicability of thin-pl...
#1G. Goldoni(University of Modena and Reggio Emilia)
#2S. Mantovani(University of Modena and Reggio Emilia)
Abstract null null In the present paper, the crashworthiness of a thick unidirectional carbon fibre reinforced polymer is investigated. This material is manufactured via compression moulding process. A Low-Velocity Impact (LVI) test is implemented on a quasi-isotropic laminate for the experimental evaluation of the energy absorption due to impact, while the internal failure mechanism is detected using Computerized Tomography (CT). Two different Finite Element (FE) models are applied to model the...
#2Rodrigo P. Tavares(National Institute of Statistics and Geography)H-Index: 5
Last. Pedro P. Camanho(National Institute of Statistics and Geography)H-Index: 70
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This work presents the results of an experimental study performed in carbon/epoxy composite materials manufactured using a ply-level hybridization technique. The aim of the study is to investigate ...
#1S. Gomarasca(TU Delft: Delft University of Technology)
#2D.M.J. Peeters(TU Delft: Delft University of Technology)
Last. Clemens Dransfeld(TU Delft: Delft University of Technology)H-Index: 13
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Abstract null null Understanding the three-dimensional variability of unidirectional composites is relevant to the material performance and the development of advanced material modelling strategies. This work proposes a new methodology for the characterisation of unidirectional composites, showcased on carbon fibre/poly(ether-ether-ketone) tapes. Three microstructural descriptors were here introduced, each representing an increasing level of complexity in the fibre architecture: from a tortuosit...
Abstract This paper introduces new composite architectures using carbon and glass fibre-reinforced epoxy prepregs to achieve gradual failure under bending. The concept is based on a technique developed by the authors to design hybrid composites with gradual failure in tension combined with beam theory to identify and control the failure sequence of the plies in the layups. Two layups are designed based on standard ply thickness S-Glass and hybrid sub-laminates made out of intermediate and high m...
#1Ryoma Aoki(UTokyo: University of Tokyo)H-Index: 2
#2Ryo Higuchi(UTokyo: University of Tokyo)H-Index: 20
Last. Toshio Ogasawara(TUAT: Tokyo University of Agriculture and Technology)H-Index: 29
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Abstract null null Thin-ply composites are gaining significant attention owing to their high damage resistance and their ability to enhance design flexibility in a composite structure. Herein we proposed a damage mechanics model considering diffuse and discrete ply damages in thin-ply composite laminates for mesoscale simulation. To investigate the effects of ply thickness on damage evolution, loading and unloading tests were conducted using cross-ply, angle-ply, and quasi-isotropic laminates wi...
#1Xinchen Ni(MIT: Massachusetts Institute of Technology)H-Index: 5
#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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Abstract In situ X-ray synchrotron radiation computed tomography (SRCT) of carbon fiber composite laminates reveals the first-ever qualitative and quantitative comparisons of 3D progressive damage effects introduced by two mechanical enhancement technologies: aligned nanoscale fiber interlaminar reinforcement and thin-ply layers. The technologies were studied individually and in combination, using aerospace-grade unidirectional prepreg standard-thickness prepreg (‘std-ply’) and thin-ply composit...
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...
#1Benedikt Kötter(TUHH: Hamburg University of Technology)H-Index: 3
#2Janina Endres(TUHH: Hamburg University of Technology)
Last. Bodo Fiedler(TUHH: Hamburg University of Technology)H-Index: 27
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Abstract This study investigates the influence of load ratio and impact damage on the fatigue behaviour of high-performance carbon fibre reinforced polymers (CFRP) with areal fibre weights between 30 gsm and 360 gsm. For undamaged samples, the ultimate tensile and compressive strength, as well as the fatigue properties, are evaluated with regard to their layer thicknesses. The fatigue tests were performed under tension-tension (R=0.1), tension-compression (R=-0.5) and compression-compression (R=...
Abstract In this paper, we present a novel model to predict the energy dissipation in composite laminates during out-of-plane loading based on experimental observations. Damage mechanisms and their sequences in composite laminates under out-of-plane loading were experimentally investigated and correlated with the energy dissipated during loading. The results showed that the energy dissipated during fiber breakage was around 3 times larger than that for delamination propagation. The first damage ...
Last. Bodo Fiedler(TUHH: Hamburg University of Technology)H-Index: 27
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Abstract Different bio-inspired Bouligand thin-ply Carbon-Fibre-Reinforced Plastic (CFRP) laminates with a pitch angle as low as 2 . 07 ∘ are realised, which is the smallest pitch angle realised in literature. The angle is therefore close angles found in biological microstructures. Low-Velocity Impact (LVI) and residual compressive strength tests determined the damage tolerance of the structures. Investigated were two different interlaminar fracture toughnesses and two different metal-Bouligand-...
