| 1. |
- Asp, Lars Erik, et al.
(författare)
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Structural power composites
- 2014
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Ingår i: Composites Science And Technology. - : Elsevier Ltd. - 0266-3538 .- 1879-1050. ; 101, s. 41-61
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces the concept of structural power composite materials and their possible devices and the rationale for developing them. The paper presents a comprehensive review of the state-of-the-art, highlighting achievements related to structural battery and supercapacitor devices. The research areas addressed in detail for the two types of material devices include: carbon fibre electrodes, structural separators, multifunctional matrix materials, device architectures and material functionalization. Material characterisation, fabrication and validation are also discussed. The paper culminates in a detailed description of scientific challenges, both generic as well as device specific, that call for further research. Particular reference is given to work performed in national and European research projects under the leadership of the authors, who are able to provide a unique insight into this newly emerging and exciting field.
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| 2. |
- Bachinger, Angelika, et al.
(författare)
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Electrocoating of carbon fibres at ambient conditions
- 2016
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Ingår i: Composites Part B. - : Elsevier Ltd. - 1359-8368 .- 1879-1069. ; 91, s. 94-102
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Tidskriftsartikel (refereegranskat)abstract
- Electrocoating at constant current is less sensitive to moisture and oxygen than electrocoating at controlled potential, which makes it more interesting for industrial implementation. The galvanostatic electrocoating of carbon fibres with Poly(methylmethacrylate) (PMMA) was therefore studied and compared to the well researched potentiostatic electrocoating procedure. The influence of different experimental parameters on the coating efficiency was investigated in order to identify the mechanisms that are involved in the cathodic electrocoating at constant current. It could be confirmed that the involved mechanisms differ from potentiostatic electrocoating and it was found that galvanostatic electrocoating is more efficient at ambient conditions compared to potentiostatic electrocoating. Polymer layers that cover the entire carbon fibre surface could be achieved in a continuous process by galvanostatic electrocoating under ambient conditions.
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| 3. |
- Edgren, Fredrik, et al.
(författare)
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Compressive failure of impacted NCF composite sandwich panels - Characterisation of the failure process
- 2004
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Ingår i: Journal of composite materials. - : SAGE Publications. - 0021-9983 .- 1530-793X. ; 38:6, s. 495-514
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, non-crimp fabric (NCF) composite face sheet sandwich panels have been tested in compression after impact (CAI). Damage in the face sheets was characterised by fractography. Compression after impact loaded panels were found to fail by plastic fibre microbuckling (kinking) in the damaged face sheet. Studies of panels for which loading was interrupted prior to failure revealed extensive stable kink band formation at several positions and in numerous plies. Kink bands initiated and propagated within a wide region close to the point of impact. In addition, kink bands initiated in zones with high shear stresses, away from the impact centre line. Consequently, the fractographic results from this investigation do not support the assumption of modelling the impact damage as an equivalent hole. To achieve accurate predictions of kink band initiation, the stress field must be known. The results from this study imply that bending effects caused by remaining dent or material eccentricities in the damaged region must be considered.
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| 4. |
- Molker, Henrik, 1979, et al.
(författare)
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Orthotropic criteria for transverse failure of non-crimp fabric-reinforced composites
- 2016
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Ingår i: Journal of composite materials. - : SAGE Publications Ltd. - 0021-9983 .- 1530-793X. ; 50:18, s. 2445-2458
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a set of failure criteria for transverse failure in non-crimp fabric-reinforced composites is presented. The proposed failure criteria are physically based and take into account the orthotropic character of non-crimp fabric composites addressing the observed lack of transverse isotropy. Experimental data for transverse loading out-of-plane in combination with in-plane loads are scarce. Therefore, to validate the developed criteria, experimental data are complemented with numerical data from a representative volume element model using a meso-micromechanical approach. The representative volume element model also provides a deeper understanding of how failure occurs in non-crimp fabric composites. Strength predictions from the developed set of failure criteria show good agreement with the experimental and numerical data. © The Author(s) 2015.
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| 5. |
- Alves, Marco, et al.
(författare)
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Thin ply sheet molding compound enables thin laminates with properties as of continuous fibers
- 2020
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Ingår i: International SAMPE Technical Conference. ; 2020-June
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Konferensbidrag (refereegranskat)abstract
- In a research collaboration with Chalmers University of Technology, KTH Royal Institute of Technology (SWE) and Imperial College (UK), Oxeon AB has developed ultrathin carbon fiber sheet molding compound (SMC) products for high performance, thin laminate and ease of manufacture composite applications. Said SMC products are based on ultrathin (0.02 mm or 0.0008 in) Spread Tow Tapes that are cut by length and randomly distributed in order to obtain a preform with an in-plane isotropy in either dry or pre-impregnated form displaying the previously never seen minimum cured plate thickness of about 0.5 mm. Recent work has demonstrated that these SMC materials can reach high stiffness and strength making them good alternatives to metal alloys or even continuous fiber composites. In the conduced work, SMC composites were manufactured using ultra-thin tapes of high modulus and ultrahigh modulus fibers having a large length-to-thickness ratio. The paper will describe how these SMC products lead to high stiffness and to significant increase in strength compared to commercially available SMC materials.
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| 6. |
- Alves, Marco, et al.
(författare)
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Ultra-strong and stiff randomly-oriented discontinuous composites: closing the gap to quasi-isotropic continuous-fibre laminates
- 2020
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Ingår i: Composites Part A: Applied Science and Manufacturing. - : Elsevier BV. - 1359-835X. ; 132
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Tidskriftsartikel (refereegranskat)abstract
- Conventional randomly-oriented Tow Based Discontinuous Composites (TBDCs) are materials which combine good mechanical properties, lightweight and high manufacturability, and are therefore interesting for high-volume transport industries. This paper proposes, designs and successfully demonstrates a pathway to produce TBDCs with outstanding stiffness and tensile strength, by using ultra-thin tapes of (ultra-) high modulus carbonfibres. Numerical models are used to explore the design space of discontinuous composite materials, in order to identify the optimal microstructural design to maximise stiffness and strength. Selected microstructures are manufactured and tested under tension; the experimental results show good agreement with the numerical predictions, and demonstrate a significant increase in the tensile strength and Young's modulus of TBDCs by reducing the tow thickness and increasing the modulus of the fibres. Strength and stiffness increases of over 100% compared with the commercially available TBDC systems are achieved, resulting in mechanical properties that match the strength and overcome the stiffness of aerospace-graded continuous-fibre laminates.
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| 7. |
- Alves, Marco, et al.
(författare)
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Ultra-Thin and Stiff Randomly-Oriented Discontinuous Composites
- 2019
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Ingår i: Proceedings of the American Society for Composites - 34th Technical Conference, ASC 2019. - Lancaster, PA : DEStech Publications, Inc..
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Konferensbidrag (refereegranskat)abstract
- This paper presents experimental and numerical results for tensile strength of tow based discontinues composite (TBDC) plates manufactured using ultra-thin fibre tapes of high stiffness carbon fibres. Numerical models were used to explore the design space of these materials, in order to identify the optimal tow properties that maximise the strength of TBDCs. The experimental show good agreement with the numerical predictions and demonstrate a significant increase in the tensile strength by reducing the tow thickness and increasing the stiffness of the fibres. Strength increases of up to 100%, compared with a commercially available material system, are found, illustrating the highly promising potential of this type of material.
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| 8. |
- André, Alann, 1980, et al.
(författare)
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Compression failure mechanism in small scale timber specimens
- 2014
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Ingår i: Construction and Building Materials. - : Elsevier BV. - 0950-0618 .- 1879-0526. ; 50, s. 130-139
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the failure mechanism of wood loaded in compression parallel to the grain has been shown to be an important parameter in the design of timber beams strengthened with fibre-reinforced plastics (FRP). In this paper, a constitutive relationship for wood under uniaxial compression load parallel to the grain was determined experimentally. Several parameters, such as silviculture, moisture content and radial position in the log in relation to the pith from where the specimen was sawn, were considered. Small clear-wood specimens were used. The strain localisation in the failure region (kinkband) was monitored using the digital image correlation method. The results show that silviculture and moisture content are two very important parameters which influence the compression failure mechanism. Furthermore, there is a significant difference in behaviour between specimens from the juvenile region of the log and specimens from mature wood. Based on experimental results, two numerical models were built, considering either a global or a local constitutive relationship. It was demonstrated that both numerical models yield accurate results and that, depending on the experimental equipment available, a constitutive relationship could be extracted and used as input in these numerical models. (C) 2013 Elsevier Ltd. All rights reserved.
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| 9. |
- André, Alann, et al.
(författare)
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Finite element delamination study of a notched composite plate under flexural loads
- 2009
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Ingår i: ICCM-17, 17th International Conference on Composite Materials, Edinburgh, UK. - London : IOM Communications.
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Konferensbidrag (refereegranskat)abstract
- The delamination process in notched composite plates under flexural loading has been investigated using finite element analysis. Cohesive elements implemented in the commercial finite element package ABAQUS have been used in the region around the drilled-hole, and positioned between layers where delamination was observed during experiments presented in an accompanying paper. The delamination initiation and subsequent propagation was studied between the layers at the tension side separately and simultaneously. For all FE models, the load displacement curve was in good agreement with the one from experiments. However, the amount of damage reported from the fractography study was more extensive than that predicted by the models. Finally, it was shown that the models with only one cohesive layer show significantly different results to that of the model with four cohesive layers in terms of size of the degradation area.
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| 10. |
- André, Alann, 1980, et al.
(författare)
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Finite Element Delamination Study of a Notched Composite Plate under Flexural Loads
- 2010
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Ingår i: Journal of Materials Science and Engineering. - 1934-8959. ; 4:8, s. 66-73
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Tidskriftsartikel (refereegranskat)abstract
- The delamination process in notched composite plates under flexural loading has been investigated using finite elementanalysis. Cohesive elements implemented in the commercial finite element package ABAQUS have been used in the region around the drilled-hole, and positioned between layers where delamination was observed during experiments presented in an accompanying paper.The delamination initiation and subsequent propagation was studied between the layers at the tension side separately and simultaneously. For all FE models, the load displacement curve was in good agreement with the one from experiments. However, the amount of damage reported from the fractography study was more extensive than that predicted by the models. Finally, it was shown that the models with only one cohesive layer show significantly different results to that of the model with four cohesive layers in terms of size of the degradation area.
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