Publications
236 results found
Lee C, Greenhalgh E, Panesar A, 2019, Optimised laminated composite ship-structures against wave impact for enhanced dynamic stiffness, Inter-noise 2019, Publisher: International Institute of Noise Control Engineering (I-INCE), ISSN: 0105-175X
Fibre-reinforced laminated composites are increasingly being utilised in marine and offshore structures due to their superior stiffness and strength to weight ratios, such as resistance to corrosion and enhanced toughness over conventional materials like steel and aluminium. A potential application of composites is in the design of wave-breakers on ship structures. These structures absorb the impact energies from a wave slam to ensure vessel serviceability and safety. The inherent anisotropy of composites and the associated dynamic loading characteristics, make the design process for such a structure very challenging. There are limited studies looking at the design optimisation of composite structures under wave impact loads. In particular, dynamic optimisation based on modal vibration characteristics has not been sufficiently studied. In this study, we have optimised a composite wave-breaker to improve the specific dynamic stiffness based on modal vibration characteristics. To tackle this problem, a multi-level optimisation procedure has been adopted; firstly, the minimum thickness of the composite plate has been determined to avoid delamination; subsequently, the stacking sequence has been identified using lamination parameters along with local thickness variation. Importantly, the optimal arrangement of damping materials (sandwiched between plies) has also been investigated to further enhance the dynamic energy dissipation performance.
Nguyen S, Corey M, Chan W, et al., 2019, Experimental determination of the aerodynamic coefficients of spinning bodies, The Aeronautical Journal, Vol: 123, Pages: 678-705, ISSN: 0001-9240
To accurately predict the probabilities of impact damage to aircraft from runway debris, it is important to understand and quantify the aerodynamic forces that contribute to runway debris lofting. These lift and drag forces were therefore measured in experiments with various bodies spun over a range of angular velocities and Reynolds numbers. For a smooth sphere, the Magnus effect was observed for ratios of spin speed to flow speed between 0.3 and 0.4, but a negative Magnus force was observed at high Reynolds numbers as a transitional boundary layer region was approached. Similar relationships between lift and spin rate were found for both cube- and cylinder-shaped test objects, particularly with a ratio of spin speed to flow speed above 0.3, which suggested comparable separation patterns between rapidly spinning cubes and cylinders. A tumbling smooth ellipsoid had aerodynamic characteristics similar to that of a smooth sphere at a high spin rate. Surface roughness in the form of attached sandpaper increased the average lift on the cylinder by 24%, and approximately doubled the lift acting on the ellipsoid in both rolling and tumbling configurations.
Zainol Abidin MS, Herceg T, Greenhalgh ES, et al., 2019, Enhanced fracture toughness of hierarchical carbon nanotube reinforced carbon fibre epoxy composites with engineered matrix microstructure, Composites Science and Technology, Vol: 170, Pages: 85-92, ISSN: 0266-3538
Fibre reinforced hierarchical composites further reinforced with up to 25 wt.% of carbon nanotubes (CNTs) were manufactured using a wet powder impregnation route. Microstructural heterogeneity in the matrix of these laminates was engineered during wet powder impregnation to produce CNTs rich regions with spatial separation. The Mode I fracture toughness of these heterogeneous hierarchical composites increased by 41% and 26% compared to that of baseline carbon fibre epoxy composites and hierarchical composites with homogeneously distributed CNTs throughout the matrix with similar CNT content, respectively. Increased crack path tortuosity was observed to contribute to this increase in fracture toughness. The interlaminar shear strength was unaffected by the matrix microstructural heterogeneity.
Mohsin M, Iannucci L, Greenhalgh E, 2019, Fibre-volume-fraction measurement of carbon fibre reinforced thermoplastic composites using thermogravimetric analysis, Heliyon, Vol: 5, ISSN: 2405-8440
The fibre-volume-fraction (FVF) measurement of fibre-reinforced polymers (FRPs) is crucial in understanding and characterising their mechanical performance. To date, there has not been a standardised, labour-efficient method in determining the FVF of a non-crimp fabric (NCF) carbon reinforced thermoplastic composites (CFRTPs). An alternative method such as thermogravimetric analysis (TGA) has merely been commonly used for carbon-fibre reinforced thermosets (CFRTSs) and glass-fibre reinforced thermosets (GFRTSs). Therefore, this paper reports a range of macro TGA measurements of the constituent materials of two NCF CFRTPs; (i) T700 carbon/polyamide6.6 (PA6.6) and (ii) T700 carbon/polyphenylene sulphide (PPS). The TGA measurements were performed using two different purge gases (air and nitrogen) and the mass degradation with respect to time, temperature and atmospheres were recorded and discussed. Additionally, fractographic analysis on the fibres was carried out to scrutinise and further discuss the findings following the TGA. It was concluded that TGA provided a suitable and reliable alternative method to measure the FVF of CFRTPs.
Katafiasz TJ, Iannucci L, Greenhalgh E, 2019, Development of a novel compact tension specimen to mitigate premature compression and buckling failure modes within fibre hybrid epoxy composites, Composite Structures, Vol: 207, Pages: 93-107, ISSN: 1879-1085
A Notched Curved Compact Tension (NCCT) and Extended Notched Curved Compact Tension (ENCCT) specimen geometry are presented for the measurement of translaminar critical strain energy release rates in composite laminates with low compressive to tensile strengths. Premature compressive and buckling failure occurred when a conventional Compact Tension (CT) specimen geometry (similar to ASTM E399 [1]) was utilised for monolithic Non-Crimp Fabric (NCF) S2-Glass / MTM57 epoxy and an interlayer fibre hybrid T700 carbon spread tow / NCF S2-glass epoxy composite. The NCCT and ENCCT specimen design methodology and manufacturing routes are presented where premature compressive failure was mitigated through a curvature at the rear of the profile and the introduction of a through-thickness groove that had been pre-cured along the crack growth region. The latter ensured that buckling was eliminated, whilst stable crack growth was achieved. The development involved FE model material validation and optimisation for the novel specimen design. Experimental tests presented both interlayer and intralayer fibre hybrid composites with good repeatability and low scatter within the results.
Lee C, Greenhalgh ES, Panesar A, 2019, Optimised laminated composite ship-structures against wave impact for enhanced dynamic stiffness
Fibre-reinforced laminated composites are increasingly being utilised in marine and offshore structures due to their superior stiffness and strength to weight ratios, such as resistance to corrosion and enhanced toughness over conventional materials like steel and aluminium. A potential application of composites is in the design of wave-breakers on ship structures. These structures absorb the impact energies from a wave slam to ensure vessel serviceability and safety. The inherent anisotropy of composites and the associated dynamic loading characteristics, make the design process for such a structure very challenging. There are limited studies looking at the design optimisation of composite structures under wave impact loads. In particular, dynamic optimisation based on modal vibration characteristics has not been sufficiently studied. In this study, we have optimised a composite wave-breaker to improve the specific dynamic stiffness based on modal vibration characteristics. To tackle this problem, a multi-level optimisation procedure has been adopted; firstly, the minimum thickness of the composite plate has been determined to avoid delamination; subsequently, the stacking sequence has been identified using lamination parameters along with local thickness variation. Importantly, the optimal arrangement of damping materials (sandwiched between plies) has also been investigated to further enhance the dynamic energy dissipation performance.
Lee C, Greenhalgh ES, Panesar A, 2019, Optimised laminated composite ship-structures against wave impact for enhanced dynamic stiffness
© INTER-NOISE 2019 MADRID - 48th International Congress and Exhibition on Noise Control Engineering. All Rights Reserved. Fibre-reinforced laminated composites are increasingly being utilised in marine and offshore structures due to their superior stiffness and strength to weight ratios, such as resistance to corrosion and enhanced toughness over conventional materials like steel and aluminium. A potential application of composites is in the design of wave-breakers on ship structures. These structures absorb the impact energies from a wave slam to ensure vessel serviceability and safety. The inherent anisotropy of composites and the associated dynamic loading characteristics, make the design process for such a structure very challenging. There are limited studies looking at the design optimisation of composite structures under wave impact loads. In particular, dynamic optimisation based on modal vibration characteristics has not been sufficiently studied. In this study, we have optimised a composite wave-breaker to improve the specific dynamic stiffness based on modal vibration characteristics. To tackle this problem, a multi-level optimisation procedure has been adopted; firstly, the minimum thickness of the composite plate has been determined to avoid delamination; subsequently, the stacking sequence has been identified using lamination parameters along with local thickness variation. Importantly, the optimal arrangement of damping materials (sandwiched between plies) has also been investigated to further enhance the dynamic energy dissipation performance.
Syed Abdullah SIB, Iannucci L, Greenhalgh E, 2018, On the translaminar fracture toughness of vectran/epoxy composite material, Composite Structures, Vol: 202, Pages: 566-577, ISSN: 1879-1085
The mode I fracture toughness associated with fibre tensile failure was investigated for a Vectran/MTM57 composite system. A modified compact tension specimen was designed and manufactured to mitigate compressive and buckling failure due to the low compressive properties which are an inherent characteristic of Vectran fibres. On average, the mode I translaminar fracture toughness for Vectran/MTM57 was found to be approximately 130–145 kJ/m2 for initiation and 250–260 kJ/m2 for propagation. In contrast with other composite systems such as carbon and glass fibre, the fracture toughness of Vectran/MTM57 was found to be relatively higher, with up to 48.26% and 95.27% for initiation and propagation, respectively for some carbon fibre composite system; 9.93% and 68.6% for initiation and propagation, respectively for S2-Glass/epoxy system.
Brandley E, Greenhalgh E, Shaffer M, et al., 2018, Mapping carbon nanotube orientation by fast fourier transform of scanning electron micrographs, Carbon, Vol: 137, Pages: 78-87, ISSN: 0008-6223
A novel method of applying a two-dimensional Fourier transform (2D-FFT) to SEM was developed to map the CNT orientation in pre-formed arrays. Local 2D-FFTs were integrated azimuthally to determine an orientation distribution function and the associated Herman parameter. This approach provides data rapidly and over a wide range of lengthscales.Although likely to be applicable to a wide range of anisotropic nanoscale structures, the method was specifically developed to study CNT veils, a system in which orientation critically controls mechanical properties. Using this system as a model, key parameters for the 2D-FFT analysis were optimised, including magnification and domain size; a model set of CNT veils were pre-strained to 5%, 10% and 15%, to vary the alignment degree. The algorithm confirmed a narrower orientation distribution function and increasing Herman parameter, with increasing pre-strain.To validate the algorithm, the local orientation was compared to that derived from a common polarised Raman spectroscopy. Orientation maps of the Herman parameter, derived by both methods, showed good agreement. Quantitatively, the mean Herman parameter calculated using the polarised Raman spectroscopy was 0.42 ± 0.004 compared to 0.32 ± 0.002 for the 2D-FFT method, with a correlation coefficient of 0.73. Possible reasons for the modest and systematic discrepancy were discussed.
Javaid A, Ho KKC, Bismarck A, et al., 2018, Improving the multifunctional behaviour of structural supercapacitors by incorporating chemically activated carbon fibres and mesoporous silica particles as reinforcement, JOURNAL OF COMPOSITE MATERIALS, Vol: 52, Pages: 3085-3097, ISSN: 0021-9983
Anthony DB, Sui X, Kellersztein I, et al., 2018, Continuous carbon nanotube synthesis on charged carbon fibers, Composites Part A: Applied Science and Manufacturing, Vol: 112, Pages: 525-538, ISSN: 1359-835X
Carbon nanotube grafted carbon fibers (CNT-g-CFs) were prepared continuously, spool to spool, via thermal CVD. The application of an in-situ potential difference (300 V), between the fibers and a cylindrical graphite foil counter electrode, enhanced the growth, producing a uniform coverage of carbon nanotubes with diameter ca. 10 nm and length ca. 125 nm. Single fiber tensile tests show that this approach avoids the significant reduction of the underlying carbon fiber strengths, which is usually associated with CVD grafting processes. Single fiber fragmentation tests in epoxy, with in-situ video fragment detection, demonstrated that the CNT-g-CFs have the highest interfacial shear strength reported for such systems (101 ± 5 MPa), comparable to state–of–the–art sizing controls (103 ± 8 MPa). Single fiber pull-out data show similar trends. The short length of the grafted CNTs is particularly attractive for retaining the volume fraction of the primary fibers in composite applications. The results are compared with a short review of the interfacial data available for related systems.
Yu Z, Greenhalgh E, Allegri G, 2017, Fractographic investigation on temperature-modified fibre/matrix interface of carbon fibre reinforced composite, ICCM Conferences
© 2017 International Committee on Composite Materials. All rights reserved. The influence of environment on carbon fibre reinforced composites has attracted widespread attention. Once exposed to high temperature, the subsequent degradation of polymeric matrices as well as fibre/matrix interfaces has a huge impact on relevant mechanical properties. In this study, carbon-epoxy composite coupons were subjected to heat-treatment in a furnace with controlled temperature. Finite element analysis was utilized to pinpoint the appropriate temperature cycle. Heat-treated components were then examined by Dynamic Mechanical Analysis (DMA), interlaminar shear strength and fractographic investigation via scanning electron microscopy (SEM). Although there has been no significant change in interlaminar shear strengths, fractographic morphologies such as shear cusps and crows-feet underwent evident alteration during SEM investigation. Densities and dimensions of crazing, cusps, crows-feet, microcracks and voids on fibre imprints showed substantial reductions as heat-treatment temperatures and duration increased. The results provided beneficial insights to future studies on temperature effects on composite structures of a larger scale.
De Luca, Anthony DB, Greenhalgh ES, et al., 2017, Continuous production of carbon nanotube-grafted quartz fibres: Effect of carbon nanotube length on fibre/matrix adhesion, 21st International Conference on Composite Materials, Publisher: Chinese Society for Composite Materials
Here, the continuous production of carbon nanotube-grafted-quartz-fibres was performed in an open chemical vapour deposition reactor with continuous in line catalyst deposition. Highly graphitic carbon nanotubes (CNTs) with controllable lengths ranging from 0.1 μm to 20 μm were grown on the quartz fibre surface by adjusting the reduction and growth times, with shorter fibres growing homogeneously and longer CNTs growing in a splayed “Mohawk” manner. The effect of CNTs length (and thus microstructure) upon the mechanical properties of CNT-grafted-quartz-fibre/epoxy composites was investigated through single fibre pull-out test. The presence of a uniform coverage of sub-micron long CNTs led to an increase in interfacial shear strength of 11% and 29% when compared to sized and de-sized quartz fibres, respectively.
Brandley E, Li Q, Greenhalgh E, et al., 2017, Full paper – Alignment study of CNT veils and the influence on their composites, 21 st International Conference on Composite Materials
© 2017 International Committee on Composite Materials. All rights reserved. A methodology was developed to measure the alignment of carbon nanotubes in pre-strained samples of carbon nanotube veils via image processing techniques. The methodology was used on samples of as-received and pre-strained carbon nanotube veils and calculated an increased Herman parameter for the pre-strained sample relative to the as-received. A number of image processing techniques, specifically high and low pass filters, were tested in order to increase the signal of the carbon nanotubes in the scanning electron micrographs, however it was found filtering the micrograph prior did not enhance nanotube signal and did not improve the calculated orientation distribution function.
Nguyen SN, Gispert CC, Greenhalgh ES, et al., 2017, A new test method to characterize mixed mode II/III and I/II/III delamination, 21st International Conference on Composite Materials
© 2017 International Committee on Composite Materials. All rights reserved. Delamination is a critical damage mechanism in laminated composites, and currently represents the greatest limitation to achieving lightweight damage tolerant designs of primary aircraft structures. Current mode III delamination toughness tests often generate additional damage processes other than mode III delamination, such as intralaminar ply splits and crack migration to neighbouring ply interfaces, which invalidate the toughness measurements. In this study, a test rig capable of generating mode II/III and I/II/III delaminations over a range of mode mixities, up to a threshold proportion of mode III, and almost uniform mode III strain energy release rates, has been designed, developed, trialled and validated. Preliminary mixed-mode tests have been conducted on Hexcel IM7/8552 with 0°/0° and 0°/90° ply interfaces at the delamination plane. Fractography has been performed to elucidate and understand the failure mechanisms and characterize the fracture morphologies associated with mixed-mode II/III and I/II/III delamination. The fracture morphology of the IM7/8552 toughness coupons with a 0°/0° ply interface under pure mode II and mode II/III loading was exclusively delamination with little evidence of ply splitting or migration having had occurred. Directly ahead of the starter crack, the fracture morphology for both loading conditions presented a wedge of torn matrix, associated with the resin fillet. Beyond this fillet region, mode II/III loading presented slightly rotated cusps and a minor degree of fibre bridging. In summary, this paper presents a new mixed mode delamination test configuration, which still needs significant further development from the research community. In particular, the constraints applied to the specimen to achieve greater mode III components needs to be addressed. However, this new test method does offer a means to characterize delamin
Mohsin MAA, Iannucci L, Greenhalgh ES, 2017, Low-velocity impact performance of carbon fibre reinforced thermoplastic composites for automotive applications, 21st International Conference on Composite Materials
© 2017 International Committee on Composite Materials. All rights reserved. The damage response of rectangular plates of three different composite systems; two carbon/thermoplastic (T700/polyamide 6.6 and T700/polyphenylene sulphide) and one carbon/thermoset (T700/MTM57), at three distinct energy levels (40, 100 and 160) has been characterised. The varying energy levels were determined to correspond to the several degrees of penetrability; no penetration (at 40), partial-penetration (at 100) and full-penetration (at 160). Each plate was subjected to an out-of-plane, localised impact using an INSTRON® drop-weight tower with a hemispherical impactor measuring 16 in diameter. Following the test results and data reduction, the low-velocity impact (LVI) performance of the different composite systems was ranked from best to worst (based on the amount of impact energy absorption per areal weight) as follows; (i) T700/PPS, (ii) T700/MTM57 and (iii) T700/PA6.6. Post-mortem analysis techniques such as C-scan and X-ray were used to investigate the extent of damage of each sample; it was concluded that the T700/PA6.6 and T700/MTM57 experienced comparable levels of localised penetration whereas the best-performing T700/PPS exhibited no penetration (even at the highest energy level) but instead, demonstrated relatively significant degree of delamination in comparison to other two.
Anthony DB, Qian H, Clancy AJ, et al., 2017, Applying a potential difference to minimise damage to carbon fibres during carbon nanotube grafting by chemical vapour deposition, Nanotechnology, Vol: 28, ISSN: 1361-6528
The application of an in-situ potential difference between carbon fibres and a graphite foil counter electrode (300 V, generating an electric field ca. 0.3 V μm-1 to 0.7 V μm-1) during the chemical vapour deposition synthesis of carbon nanotube (CNT) grafted carbon fibres, significantly improves the uniformity of growth without reducing the tensile properties of the underlying carbon fibres. Grafted carbon nanotubes with diameters around 55 nm and lengths around 10 μm were well attached to the carbon fibre surface, and were grown without the requirement for protective barrier coatings. The grafted CNTs increased the surface area to 185 m2 g-1 compared to the as-received sized carbon fibre 0.24 m2 g-1. The approach is not restricted to batch systems and has the potential to improve carbon nanotube grafted carbon fibre production for continuous processing.
Mohsin MAA, Iannucci L, Greenhalgh E, 2017, Mode I interlaminar fracture toughness characterisation of carbon fibre reinforced thermoplastic composites, Pages: 372-383
Delamination has always been regarded as one of the most critical failures in laminated composites. The growing interest in a more rapid, out-of-autoclave (OOA) manufacturing techniques for automotive applications such as compression moulding and thermoforming has prompted the engineering community to further investigate and understand the delamination resistance of carbon fibre reinforced thermoplastic (CFRTP) composites over the more conventional carbon fibre reinforced thermosetting (CFRTS) counterparts. In this study, the mode I (opening) interlaminar fracture toughness of two non-crimp fabric (NCF) biaxial (0/90º) carbon/thermoplastic composite systems with fibre volume fraction (FVF) of 50%; T700/polyamide 6.6 and T700/polyphenylene sulphide have been characterised. The mode I delamination resistance, for both materials was determined using the double cantilever beam (DCB) specimen. Following the experimental results and data reduction, the Mode I interlaminar fracture toughness were compared. Fractographic analysis was conducted using a scanning electron microscope (SEM) to characterise the microstructure of the failed specimens.
Anthony DB, bismarck A, blaker JJ, et al., 2016, Development of novel composites through fibre and interface/interphase modification, 37th Risø International Symposium on Materials Science, Publisher: IOP, Pages: 012001-012001, ISSN: 1757-8981
We show how fibre/matrix interface (or interphase) modification can be used to develop a range of novel carbon fibre reinforced polymer (CFRP) composites that open up new applications far beyond those of standard CFRPs. For example, composites that undergo pseudo-ductile failure have been created through laser treatment of carbon fibres. Composites manufactured with thermo-responsive interphases can undergo significant reductions in stiffness at elevated temperatures. Additionally, structural supercapacitors have been developed through a process that involves encapsulating carbon fibres in carbon aerogel.
De Luca H, Anthony DB, Qian H, et al., 2016, Non-damaging and scalable carbon nanotube synthesis on carbon fibres, ECCM17 - 17th European Conference on Composite Materials
The growth of carbon nanotubes (CNTs) on carbon fibres (CFs) to produce a hierarchical fibre with two differing reinforcement length scales, in this instance nanometre and micrometre respectively, is considered a route to improve current state-of-the-art fibre reinforced composites [1]. The scalable production of carbon nanotube-grafted-carbon fibres (CNT-g-CFs) has been limited due to high temperatures, the use of flammable gases and the requirement of inert conditions for CNT synthesis, whist (ideally) maintaining underlying original substrate mechanical properties. Here, the continuous production of CNT-g-CF is demonstrated in an open chemical vapour deposition (CVD) reactor, crucially, whilst retaining the tensile properties of the carbon fibres. As synthesised CNTs have a diameter of sub 20 nm and length ca. 120 nm, which are predicted to provide ideal fibre reinforcement in composites by retaining optimal composite fibre volume fraction (60%), whilst improving interfacial bonding of the matrix and reinforcement [1, 2]. Mild processing techniques enable this modified CVD process to be fully compatible with industrial practices, and have the potential to generate large volumes of hierarchical CNT-g-CF material.
Razavi S, Iannucci L, Greenhalgh ES, 2016, Piezoelectric smart fibre sensor, 17th European Conference on Composite Materials
Herceg TM, Abidin MSZ, Greenhalgh ES, et al., 2016, Thermosetting hierarchical composites with high carbon nanotube loadings: en route to high performance, Composites Science and Technology, Vol: 127, Pages: 134-141, ISSN: 0266-3538
A wet powder impregnation route to manufacture carbon fibre reinforced thermoplastic composites was adapted to accommodate thermosetting matrices reinforced with high fractions (20 wt%/13.6 vol%) of multiwalled carbon nanotubes (CNTs). The produced carbon fibre prepregs were consolidated into laminates with fibre volume fractions of 50–58% and up to 6.1 vol% CNTs. Microscopic imaging confirmed successful consolidation at intermediate CNT loadings, but some voidage at the highest CNT loading due to the highly viscoelastic uncured matrix. Nonetheless, through-thickness electrical conductivity and Mode I interlaminar fracture toughness were enhanced by as much as 152% and 24% to unprecedented values of σ = 53 S m−1 and GIC = 840 J m−2, respectively. Fractographic characterisation indicated that crack deflection was the mechanism responsible for the improved fracture toughness. The material properties were shown to be strongly dependent on the microstructure of the matrix.
Herceg TM, Yoon S-H, Abidin MSZ, et al., 2016, Thermosetting nanocomposites with high carbon nanotube loadings processed by a scalable powder based method, Composites Science and Technology, Vol: 127, Pages: 62-70, ISSN: 0266-3538
A powder based processing route was developed to allow manufacturing of thermosettingnanocomposites with high (20 wt%) carbon nanotube (CNT) loading fractions. Adaptation ofhigh shear mixing methods, as used in thermoplastic processing, ensured that the CNTs werewell distributed and dispersed even at the highest loadings. By minimising flow distances,compression moulding of powders ensured that the CNTs did not agglomerate duringconsolidation, and yielded a percolated CNT network in a nanocomposite with excellentelectrical and thermal conductivities of 67 S m-1and 0.77 W m-1 K-1, respectively. Unusually,the CNTs provided effective mechanical reinforcement at even the highest loadings;embrittlement is minimised by avoiding large scale inhomogeneities and the maximummeasured Young’s modulus (5.4 GPa) and yield strength (90 MPa) could make thenanocomposite an attractive matrix for continuous fibre composites. The macromechanicalmeasurements were interpolated using micromechanical models that were previouslysuccessfully applied at the nanoscale.
Razavi S, Iannucci L, Greenhalgh ES, 2016, Piezoelectric PVDF smart fibre for composite applications, 17th European Conference on Composite Materials, Pages: 1-8
This research project aims to use the braiding manufacturing technique to produce a Polyvinylidene Fluoride (PVDF) 'smart fibre'. The smart fibre is a piezoelectric co-axial cable comprised of a conductive core electrode, piezoelectric PVDF-braided yarns, and a conductive wire outer electrode. A custom-design poling apparatus has been fabricated to induce a permanent piezoelectric effect into the PVDF yarns-using, whilst no inner core electrode, based on utilising the Simultaneous Stretching and Corona Poling (SSPC) technique. This method is advantageous in terms of avoiding the challenges associated with the use of in-line poling techniques, which are commonly used for the manufacturing of fibre-based piezoelectric PVDF sensors/energy harvesters via conventional hot-melt extrusion methods. A secondary method of poling was also investigated through incorporating a 0.4 mm copper wire core electrode with eight braided strands of a 0.1mm copper wire outer electrode, which are connected to a source of high-voltage DC potential to create a high electric field on the PVDF-braided structure in-between. In addition, a series of tensile tests were carried out on the PVDF-braided conductive core wires including: Zylone 1 /Copper-coated, Vectran 2 /Copper-coated, and Polyamide 66 (PA66)/Silver-coated wires; where it was observed that the piezo element sensitivity to the external mechanical stimuli could be improved when using a stiffer core electrode material. A CAD and FE model of a 100 mm gauge-length of the smart fibre with associated inner and outer electrodes, were also developed using Solidworks and COMSOL Multiphysics 5.2 software, respectively.
Katafiasz TJ, Iannucci L, Greenhalgh ES, 2016, Interlaminar and intralaminar properties of carbon spread tow and glass fibre hybrid composites for cost saving in the mass production of automotive components
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.As the efficiency of the automotive engine shows signs of slow-down and the consumer is becoming more aware of the consequential ecological impact, the industry's need for lighter component materials grows more prominent. Carbon fibre composite materials have been subject to neglect within the consumer automotive industry due to their expense (whereas glass fibre materials have been used favourably over the last few decades [1]). Cost effective composite materials have therefore become an area of interest for the consumer automotive market, where year-on-year engine efficiency performance improvements and monetary savings are integral to company profits. The purpose of this research is to verify that the use of fibre hybrid composites, where two-stage pseudoductile responses can be found [2], [3], are a viable alternative to monolithic structures (which exhibit a more traditional one-stage brittle failure) in interlaminar and intralaminar failure modes. In recent years, there has been much work to understand the tensile response of fibre hybrid composites [2]-[5] but a lack of research in types of failure modes which are more likely within automotive components; these being delamination (interlaminar) and through-thickness tearing (intralaminar); the latter of which most likely occurs at stress concentrations at bolt holes and through-thickness discontinuities.
Syed Abdullah SIB, Iannucci L, Greenhalgh ES, 2016, An experimental study of the mode i interlaminar fracture toughness of vectran/epoxy composites
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.Aircraft structures are susceptible to delamination from forward facing High Velocity Impact (HVI) in all regimes during service. Advanced composite fibres, such as Vectran could improve HVI performance on aircraft structures, hence creating a safer air travel environment. Vectran fibre are considerably tougher compared to Carbon Fibre Reinforced Plastic (CFRP). In this study, the interlaminar fracture toughness GIC of Vectran/Epoxy laminates is investigated from a Double Cantilever Beam (DCB) test, and compared to monolithic CFRP (T800s/M21). It was found that the interlaminar fracture toughness for Vectran/Epoxy material is significantly higher than that of T800s/M21 (GIC,Vectran ≈ 1.5 kJ/m2; GIC,T800s ≈ 0.246 kJ/m2).
Mohsin MAA, Iannucci L, Greenhalgh E, 2016, Translaminar fracture toughness characterisation of carbon fibre reinforced thermoplastic composites
© 2016, European Conference on Composite Materials, ECCM. All rights reserved.The translaminar fracture toughness of carbon/thermoplastic T700/PA6.6 composite system was examined. The fracture toughness test was conducted using compact tension specimens of non-crimp fabric biaxial T700 carbon fibre reinforced PA6.6. The critical strain energies, GIc0, required to initiate and propagate the crack through the specimen were found to be between 72 - 81kJ/m2 and 77 - 95kJ/m2 respectively. Two compact tension (CT) specimen configurations were validated though finite element modelling (FEM) using LS-DYNA® prior to the test.
Mohsin MAA, Iannucci L, Greenhalgh E, 2016, Translaminar fracture toughness characterisation of carbon fibre reinforced thermoplastic composites
The translaminar fracture toughness of carbon/thermoplastic T700/PA6.6 composite system was examined. The fracture toughness test was conducted using compact tension specimens of non-crimp fabric biaxial T700 carbon fibre reinforced PA6.6. The critical strain energies, GIc0, required to initiate and propagate the crack through the specimen were found to be between 72 - 81kJ/m2 and 77 - 95kJ/m2 respectively. Two compact tension (CT) specimen configurations were validated though finite element modelling (FEM) using LS-DYNA® prior to the test.
Syed Abdullah SIB, Iannucci L, Greenhalgh ES, 2016, An experimental study of the mode i interlaminar fracture toughness of vectran/epoxy composites
Aircraft structures are susceptible to delamination from forward facing High Velocity Impact (HVI) in all regimes during service. Advanced composite fibres, such as Vectran could improve HVI performance on aircraft structures, hence creating a safer air travel environment. Vectran fibre are considerably tougher compared to Carbon Fibre Reinforced Plastic (CFRP). In this study, the interlaminar fracture toughness GIC of Vectran/Epoxy laminates is investigated from a Double Cantilever Beam (DCB) test, and compared to monolithic CFRP (T800s/M21). It was found that the interlaminar fracture toughness for Vectran/Epoxy material is significantly higher than that of T800s/M21 (GIC,Vectran ≈ 1.5 kJ/m2; GIC,T800s ≈ 0.246 kJ/m2).
Katafiasz TJ, Iannucci L, Greenhalgh ES, 2016, Interlaminar and intralaminar properties of carbon spread tow and glass fibre hybrid composites for cost saving in the mass production of automotive components
As the efficiency of the automotive engine shows signs of slow-down and the consumer is becoming more aware of the consequential ecological impact, the industry's need for lighter component materials grows more prominent. Carbon fibre composite materials have been subject to neglect within the consumer automotive industry due to their expense (whereas glass fibre materials have been used favourably over the last few decades [1]). Cost effective composite materials have therefore become an area of interest for the consumer automotive market, where year-on-year engine efficiency performance improvements and monetary savings are integral to company profits. The purpose of this research is to verify that the use of fibre hybrid composites, where two-stage pseudoductile responses can be found [2], [3], are a viable alternative to monolithic structures (which exhibit a more traditional one-stage brittle failure) in interlaminar and intralaminar failure modes. In recent years, there has been much work to understand the tensile response of fibre hybrid composites [2]-[5] but a lack of research in types of failure modes which are more likely within automotive components; these being delamination (interlaminar) and through-thickness tearing (intralaminar); the latter of which most likely occurs at stress concentrations at bolt holes and through-thickness discontinuities.
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