| 1. |
- Johannisson, Wilhelm, et al.
(författare)
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A screen-printing method for manufacturing of current collectors for structural batteries
- 2021
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Ingår i: Multifunctional Materials. - : IOP Publishing. - 2399-7532. ; 4:3, s. 035002-
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Tidskriftsartikel (refereegranskat)abstract
- Structural carbon fibre composite batteries are a type of multifunctional batteries that combine the energy storage capability of a battery with the load-carrying ability of a structural material. To extract the current from the structural battery cell, current collectors are needed. However, current collectors are expensive, hard to connect to the electrode material and add mass to the system. Further, attaching the current collector to the carbon fibre electrode must not affect the electrochemical properties negatively or requires time-consuming, manual steps. This paper presents a proof-of-concept method for screen-printing of current collectors for structural carbon fibre composite batteries using silver conductive paste. Current collectors are screen-printed directly on spread carbon fibre tows and a polycarbonate carrier film. Experimental results show that the electrochemical performance of carbon fibre vs lithium metal half-cells with the screen-printed collectors is similar to reference half-cells using metal foil and silver adhered metal-foil collectors. The screen-printed current collectors fulfil the requirements for electrical conductivity, adhesion to the fibres and flexible handling of the fibre electrode. The screen-printing process is highly automatable and allows for cost-efficient upscaling to large scale manufacturing of arbitrary and complex current collector shapes. Hence, the screen-printing process shows a promising route to realization of high performing current collectors in structural batteries and potentially in other types of energy storage solutions.
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| 2. |
- Reyahi, Azadeh, et al.
(författare)
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Foxf2 Is Required for Brain Pericyte Differentiation and Development and Maintenance of the Blood-Brain Barrier
- 2015
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Ingår i: Developmental Cell. - : Elsevier BV. - 1534-5807 .- 1878-1551. ; 34:1, s. 19-32
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Tidskriftsartikel (refereegranskat)abstract
- Pericytes are critical for cerebrovascular maturation and development of the blood-brain barrier (BBB), but their role in maintenance of the adult BBB, and how CNS pericytes differ from those of other tissues, is less well understood. We show that the forkhead transcription factor Foxf2 is specifically expressed in pericytes of the brain and that Foxf2(-/-) embryos develop intracranial hemorrhage, perivascular edema, thinning of the vascular basal lamina, an increase of luminal endothelial caveolae, and a leaky BBB. Foxf2(-/-) brain pericytes were more numerous, proliferated faster, and expressed significantly less Pdgfr beta. Tgf beta-Smad2/3 signaling was attenuated, whereas phosphorylation of Smad1/5 and p38 were enhanced. Tgf beta pathway components, including Tgf beta 2, Tgf beta r2, Alk5, and integrins alpha(V)beta(8), were reduced. Foxf2 inactivation in adults resulted in BBB breakdown, endothelial thickening, and increased trans-endothelial vesicular transport. On the basis of these results, FOXF2 emerges as an interesting candidate locus for stroke susceptibility in humans.
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| 3. |
- Anthony, David B., et al.
(författare)
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STRUCTURAL SUPERCAPACITOR COMPOSITE TECHNOLOGY DEMONSTRATOR
- 2022
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Ingår i: ECCM 2022 - Proceedings of the 20th European Conference on Composite Materials: Composites Meet Sustainability. ; 5, s. 253-259
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Konferensbidrag (refereegranskat)abstract
- Structural power composites, a class of multifunctional materials, have significant potential to facilitate lightweighting and accelerate widespread electrification in sustainable transportation. In civil aircraft, a bank of supercapacitors can provide power to open the doors in an emergency. Structural power composite fuselage components near the doors could provide this power and eliminate the mass and volume needed for the supercapacitors. To demonstrate this concept, we designed and manufactured a multifunctional component representative of a fuselage rib, which powered the opening and closing of a desktop scale composite aircraft door. This paper provides information about structural supercapacitor technology demonstrators, discusses the fabrication of this demonstrator and concludes by providing an insight into the future challenges that need to be addressed to realise structural power composite components.
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| 4. |
- Furtado, Carolina, et al.
(författare)
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Effects of ply thickness and architecture on the strength of composite sub-structures
- 2021
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Ingår i: Composite Structures. - : Elsevier BV. - 0263-8223. ; 256
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Tidskriftsartikel (refereegranskat)abstract
- This work presents an experimental study on the effect of: ply thickness; ply-level hybridization; and type of ply architecture on the damage mechanisms that dominate failure and strength of multidirectional laminates. Nine effectively equivalent 0°dominated multidirectional laminates made from unidirectional carbon fibre tapes (UD), non-crimp fabrics (NCF) and spread-tow fabrics (STF) with thickness ranging from 67 μm to 268 μm are defined and tested under plain strength tension and compression, open-hole tension and compression, filled-hole compression and tension-bearing. An overall improvement of the strengths with the decrease of ply thickness is observed for the UD and NCF laminates, but nearly no effect of ply thickness is detected for STF laminates. Ply-level hybridization, where thin off-axis plies are combined with thicker grade 0°plies contributes to the improvement of the laminate response, especially when thicker 0°plies are used. However, hybrid-ply laminates are more sensitive to the loading direction and are, therefore, only suitable in structures where highly oriented loadings are expected. Fabric-based laminates do not show especial susceptibility to early failure compared to UD laminates. Their use can, therefore, be an economical solution that does not compromise the structural response, ensuring the weight benefits of composite materials at lower processing costs.
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| 5. |
- Furtado, C., et al.
(författare)
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Is there a ply thickness effect on the mode I intralaminar fracture toughness of composite laminates?
- 2020
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Ingår i: Theoretical and Applied Fracture Mechanics. - : Elsevier BV. - 0167-8442. ; 107
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Tidskriftsartikel (refereegranskat)abstract
- The apparent crack resistance curves associated with longitudinal tensile failure of carbon fibre reinforced epoxy composite systems with ply thicknesses of 0.075 mm, 0.134 mm and 0.268 mm are determined experimentally from the size effect law of geometrically similar double edge notch tension cross-ply specimens. An increase in notched strength as a function of the ply thickness and a corresponding increase of the measured intralaminar fracture toughness is observed. This increase is shown to be a consequence of the appearance of split cracks in the thicker 0 degrees plies in the vicinity of the notches. The numerical models developed demonstrate that if the notch blunting mechanisms are properly represented, the laminate strength is well predicted for a constant value of the ply intralaminar fracture toughness. This supports the hypothesis that these mechanisms are responsible for the higher strength of the thicker plies, and that the intralaminar fracture toughness of the 0 degrees plies should not be scaled with the ply thickness.
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| 6. |
- Greenhalgh, Emile S., et al.
(författare)
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En route to “massless energy” with structural power composites
- 2019
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Structural power composites are structural composites with the additional functionality of storing electrical energy. This paper provides an overview of the recent developments in structural batteries and structural supercapacitors, and an industrial perspective on the future challenges for their introduction. Popular science paper in: JEC Composites Magazine / Special Issue Smart Cities / November 2019
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| 7. |
- Ishfaq, A., et al.
(författare)
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Multifunctional design, feasibility and requirements for structural power composites in future electric air taxis
- 2023
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Ingår i: Journal of composite materials. - : SAGE Publications. - 0021-9983 .- 1530-793X. ; 57:4, s. 817-827
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates the viability of implementing multifunctional structural power composites in a four-seater air taxi, the CityAirbus. For a given specific energy of the power source, the cruise endurance can be approximately doubled by using structural power composites as opposed to conventional batteries. Replacing all the eligible composite mass and batteries with structural power composites can reduce the CityAirbus weight by 25%. To achieve the current design performance, the minimum required elastic modulus, strength, specific energy and power for the structural power composite are 54 GPa, 203 MPa, 74 Wh/kg and 376 W/kg, respectively: current state-of-the-art structural power composites are now approaching this level of performance. Hence, structural power composites are considered feasible for adoption in the urban air mobility sector and have the potential to improve endurance and facilitate commercialization. This paper also discusses several key challenges that must be addressed to realize the adoption of structural power composites in future electric air taxis.
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| 8. |
- Karadotcheva, Elitza, et al.
(författare)
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Structural power performance targets for future electric aircraft
- 2021
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Ingår i: Energies. - : MDPI AG. - 1996-1073 .- 1996-1073. ; 14:19
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Tidskriftsartikel (refereegranskat)abstract
- The development of commercial aviation is being driven by the need to improve efficiency and thereby lower emissions. All-electric aircraft present a route to eliminating direct fuel burning emissions, but their development is stifled by the limitations of current battery energy and power densities. Multifunctional structural power composites, which combine load-bearing and energy-storing functions, offer an alternative to higher-energy-density batteries and will potentially enable lighter and safer electric aircraft. This study investigated the feasibility of integrating structural power composites into future electric aircraft and assessed the impact on emissions. Using the Airbus A320 as a platform, three different electric aircraft configurations were designed conceptually, incorporating structural power composites, slender wings and distributed propulsion. The specific energy and power required for the structural power composites were estimated by determining the aircraft mission performance requirements and weight. Compared to a conventional A320, a parallel hybrid-electric A320 with structural power composites >200 Wh/kg could potentially increase fuel efficiency by 15% for a 1500 km mission. For an all-electric A320, structural power composites >400 Wh/kg could halve the specific energy or mass of batteries needed to power a 1000 km flight.
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| 9. |
- Linde, Peter, 1959, et al.
(författare)
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Mitigating the weak impact response of thin-ply based thin laminates through an unsymmetrical laminate design incorporating intermediate grade plies
- 2019
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Ingår i: Composite Structures. - : Elsevier BV. - 0263-8223. ; 220, s. 93-104
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Tidskriftsartikel (refereegranskat)abstract
- With aeronautic industries focussing on thinner structures and reducing manufacturing costs, recent research has been dedicated to the impact and post impact response of thin laminates (<2 mm) made of textile fabric composites. A recent study revealed that thin laminates based on thin plies exhibit extensive fibre failure and a reduced compression after impact strength. To mitigate this weakness, we propose a novel laminate concept based on combining plies of different thicknesses in an unsymmetrical configuration (intermediate grade plies are located only at the bottom of the laminate, i.e., the non-impacted face). C-scan inspection on impacted and quasi-statically indented specimens, allowed the damage sequence of the proposed unsymmetrical hybrid laminate to be compared with that of the thin-ply baseline. The hybrid laminate with intermediate plies at the bottom, delayed and reduced the fibre damage, decreased the projected delamination area and led to a 30% increase in the compression after impact strength in contrast to the thin-ply baseline laminate.
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| 10. |
- Nguyen, Sang N, et al.
(författare)
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Conceptual Multifunctional Design, Feasibility and Requirements for Structural Power in Aircraft Cabins
- 2021
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Ingår i: Journal of Aircraft. - 0021-8669 .- 1533-3868. ; 58:3, s. 677-687
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a theoretical investigation into the potential use of structural power composites in regional aircraft passenger cabins and the corresponding challenges to widespread use, including fire resistance, long-term cycling performance, and cost. This study focuses on adapting sandwich floor panels with structural power composite face sheets, designed to power the in-flight entertainment system. Using a simple mechanical model to define the structural requirements, based on state-of-the-art laminated structural power composites, a series of electrochemical energy storage performance targets were calculated: a specific energy >144 (W⋅h)/kg, a specific power >0.29 kW/kg, an in-plane elastic modulus >28 GPa, and in-plane tensile and compressive strengths >219 MPa. Significantly, the use of a distributed energy storage system offered a significant range of other mass and cost savings, associated with a simplified power system, and the use of ground-generated electrical energy. For an Airbus A220-100, the analysis predicted potential mass and volume savings of approximately 260 kg and 510 l and annual reductions in CO2 and NOx emissions of approximately 280 tonnes and 1.2 tonnes respectively. This extended design analysis of a specific component highlights both the far-reaching implications of implementing structural power materials and the potential extensive systemic benefits.
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| 11. |
- Nguyen, Sang N., et al.
(författare)
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Manufacture and characterisation of a structural supercapacitor demonstrator
- 2024
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Ingår i: Composites Science and Technology. - 0266-3538. ; 245
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Tidskriftsartikel (refereegranskat)abstract
- Structural power composites, a class of multifunctional materials, may facilitate lightweighting and accelerate widespread electrification of sustainable transportation. In the example considered in this paper, structural power composite fuselage components could provide power to open aircraft doors in an emergency and thus reduce or eliminate the mass and volume needed for supercapacitors currently mounted on the doors. To demonstrate this concept, an 80 cm long multifunctional composite C-section beam was designed and manufactured, which powered the opening and closing of a desktop-scale composite aircraft door. Twelve structural supercapacitor cells were made, each 30 cm × 15 cm × 0.5 mm, and two stacks of four cells were integrated into the web of the beam by interleaving and encasing them with low-temperature-cure woven carbon fibre/epoxy prepreg. This article culminates by considering the engineering challenges that need to be addressed to realise structural power composite components, particularly in an aerospace context.
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| 12. |
- Sasikumar, A., et al.
(författare)
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A virtual testing based search for optimum compression after impact strength in thin laminates using ply-thickness hybridization and unsymmetrical designs
- 2020
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Ingår i: Composites Science and Technology. - : Elsevier BV. - 0266-3538. ; 196
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Tidskriftsartikel (refereegranskat)abstract
- In the quest to improve the compression after impact (CAI) strength of thin laminates, ply-hybrid laminates (where plies of different thicknesses are mixed) have been used in a previous study to mitigate the fibre failure and, consequently, improve the CAI strength. In the same study, hybrid laminates were proposed following qualitative design rules. In this paper, we systematically look for hybrid stacking sequences with improved damage tolerance by virtually testing all the laminates in a defined design space. While the laminates in the design space are made of intermediate and thick ply grades, the baseline laminate has only intermediate grade plies. Using an in-house numerical model, we virtually tested, (impact and CAI at two impact energies), all the candidate stacking sequences. The best hybrid laminates considerably improved the CAI strength over the baseline (31% and 40% improvement for the symmetric and unsymmetrical hybrid laminates, respectively). One of the best hybrid laminates was then manufactured and tested experimentally to validate the approach. Through virtual testing, this study demonstrates the benefits of using ply thickness hybrid laminates and the feasibility of optimizing the stacking sequence for impact damage tolerance.
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| 13. |
- Sasikumar, A., et al.
(författare)
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Effect of ply thickness and ply level hybridization on the compression after impact strength of thin laminates
- 2019
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Ingår i: Composites Part A: Applied Science and Manufacturing. - : Elsevier BV. - 1359-835X. ; 121, s. 232-242
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Tidskriftsartikel (refereegranskat)abstract
- There is a lack of research available on how thin laminates respond to impact and post impact loads, even though thin structures are used in present-day aircrafts. This experimental paper employs thick, standard and thin uni-directional plies to investigate the effect ply thickness has on thin laminates on their impact and compression after impact (CAI) response. Further, we propose two hybrid laminates where thick or standard plies are mixed with thin plies, respectively, in an effort to improve the CAI strength of thin laminates. Results reveal that, contrary to thick laminates, thin laminates made of only thin plies exhibit extensive fibre failure, leading to a considerably reduced CAI strength. Moreover, the hybrid laminate where thick 0° plies are mixed with thin plies improves the CAI strength by 40% over the thin ply baseline laminate. Thus, hybridization with thin laminates appears to be an economic prospective in terms of improving damage tolerance.
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| 14. |
- Sasikumar, A., et al.
(författare)
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Impact and compression after impact response in thin laminates of spreadtow woven and non-crimp fabrics
- 2019
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Ingår i: Composite Structures. - : Elsevier BV. - 0263-8223. ; 215, s. 432-445
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Tidskriftsartikel (refereegranskat)abstract
- Recent research has been devoted to thin laminates as a result of aeronautic industries shifting to thinner and lighter structures. In an attempt to improve the out-of-plane response and reduce manufacturing costs considerably, airplane manufacturers are exploring (apart from unidirectional tapes) textile fabrics of different fabric architectures. Within the framework of thin laminates, this paper investigates the impact and compression after impact (CAI) of two types of aerospace graded spread-tow fabrics, namely non-crimp fabrics and woven fabrics, where stitching and weaving, respectively, govern the architecture. The study also comprises two different ply thicknesses (thin and intermediate ply grades) for both fabrics. Experimental results reveal that while woven fabrics display higher damage resistance, non-crimp fabrics ensure higher damage tolerance. The intermediate ply grade performed better than thin plies in terms of damage resistance and CAI strength for both fabrics, as thin ply non-crimp fabric laminates exhibited early and extensive fibre damage.
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| 15. |
- Schutzeichel, Maximilian O H, et al.
(författare)
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Experimental characterization of multifunctional polymer electrolyte coated carbon fibres
- 2019
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Ingår i: Functional Composites and Structures. - : IOP Publishing. - 2631-6331. ; 1:2
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Tidskriftsartikel (refereegranskat)abstract
- Multifunctional structures like the structural energy storage are investigated for enhanced lightweight design. Polymer electrolyte coated carbon fibres (PeCCF) function as a battery halfcell, combining negative electrode and structural electrolyte of the energy storage. The new material combination results in unknown mechanical and multiphysical effective characteristics. Looking forward to future multifunctional CFRP structures made from PeCCF, an influence of the multiphysical PeCCF properties on the CFRP laminate characteristics is expected. This paper presents experimental work, focusing on the first multiphysical characterization of state of the art PeCCF. Thereby, physical effects like the thermo-mechanical coupling in a temperature domain of 193 K
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