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Publications (10 of 83) Show all publications
André, A., Kliger, R. & Asp, L. (2014). Compression failure mechanism in small scale timber specimens (ed.). Paper presented at . Construction and Building Materials, 50, 130-139
Open this publication in new window or tab >>Compression failure mechanism in small scale timber specimens
2014 (English)In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 50, p. 130-139Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-7133 (URN)10.1016/j.conbuildmat.2013.09.018 (DOI)000330489200015 ()2-s2.0-84885963508 (Scopus ID)574656f3-7f1c-4333-b12f-56f67b0b51c0 (Local ID)574656f3-7f1c-4333-b12f-56f67b0b51c0 (Archive number)574656f3-7f1c-4333-b12f-56f67b0b51c0 (OAI)
Note
Validerad; 2014; 20131014 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Leijonmarck, S., Mathew, A. P., Oksman, K., Lindbergh, G. & Asp, L. (2014). Direct electropolymerization of polymer electrolytes onto carbon fibers - A route to structural batteries? (ed.). In: (Ed.), 16th European Conference on Composite Materials, ECCM 2014: Seville, Spain, 22 June- 26 June 2014. Paper presented at European Conference on Composite Materials : 22/06/2014 - 26/06/2014. European Conference on Composite Materials, ECCM
Open this publication in new window or tab >>Direct electropolymerization of polymer electrolytes onto carbon fibers - A route to structural batteries?
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2014 (English)In: 16th European Conference on Composite Materials, ECCM 2014: Seville, Spain, 22 June- 26 June 2014, European Conference on Composite Materials, ECCM , 2014Conference paper, Published paper (Refereed)
Abstract [en]

In an effort to further reduce weight of carbon fibre reinforced composites, the concept of structural batteries has arisen. A structural battery is a multifunctional material managing both energy storage and enabling of structural integrity. More specific, the carbon fibres in the composites are used as negative electrode in a Li-ion battery. A crucial part of such a battery is the preparation of a thin, ionically conductive and stiff polymer matrix. One route to realize this is the use of electropolymerization, which can cover each individual fibre with polymer. In this study, the surface morphology of coated carbon fibres is investigated with electron microscopy and atomic force microscopy. Additionally, the curing degree as a function of process temperature during polymerization is tested.

Place, publisher, year, edition, pages
European Conference on Composite Materials, ECCM, 2014
Keywords
Electropolymerization, Li-ion battery, Structural battery
National Category
Bio Materials
Research subject
Wood and Bionanocomposites
Identifiers
urn:nbn:se:ltu:diva-39217 (URN)84915821841 (Scopus ID)ddd94297-1a05-4fa8-ab4b-cfa3f0909271 (Local ID)9780000000002 (ISBN)ddd94297-1a05-4fa8-ab4b-cfa3f0909271 (Archive number)ddd94297-1a05-4fa8-ab4b-cfa3f0909271 (OAI)
Conference
European Conference on Composite Materials : 22/06/2014 - 26/06/2014
Note

Godkänd; 2014; 20141217 (andbra)

Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-06-14Bibliographically approved
Bachinger, A., Marklund, E., Rössler, J., Hellström, P. & Asp, L. (2014). Stiffness-modifiable composite for pedestrian protection (ed.). In: (Ed.), (Ed.), 16th European Conference on Composite Materials, ECCM 2014: Seville, Spain, 22 - 26 June 2014. Paper presented at European Conference on Composite Materials : 22/06/2014 - 26/06/2014. : European Conference on Composite Materials, ECCM
Open this publication in new window or tab >>Stiffness-modifiable composite for pedestrian protection
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2014 (English)In: 16th European Conference on Composite Materials, ECCM 2014: Seville, Spain, 22 - 26 June 2014, European Conference on Composite Materials, ECCM , 2014Conference paper, Published paper (Refereed)
Abstract [en]

A novel functional material allowing stiffness-reduction upon external stimulation was developed. Implementation of such technology in the design of a car front has high potential to result in increased protection of vulnerable road users (VRUs). The composite material is obtained by coating carbon fibres with a thermoplastic polymer in a continuous process, followed by infusion with an epoxy resin. The process is scalable for industrial use. The coating process was optimized regarding coating efficiency, energy consumption, risks involved for operating personnel and environment, and tailored to gain the optimal coating thickness obtained from numerical calculations. A drastic decrease in transversal stiffness could be detected for the composite material by dynamic mechanical thermal analysis (DMTA), when the temperature was increased above the glass transition temperature of the thermoplastic interphase. The ability of the material to achieve such temperature and associated reduction in stiffness by the application of current was verified using a special 3-point bending setup developed for this task.

Place, publisher, year, edition, pages
European Conference on Composite Materials, ECCM, 2014
Keywords
Fibre/matrix interface, Pedestrian protection, Stiffness-variable composite
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-37523 (URN)84915756456 (Scopus ID)b96281b7-3ae6-4f50-8707-5f601f35e790 (Local ID)9780000000002 (ISBN)b96281b7-3ae6-4f50-8707-5f601f35e790 (Archive number)b96281b7-3ae6-4f50-8707-5f601f35e790 (OAI)
Conference
European Conference on Composite Materials : 22/06/2014 - 26/06/2014
Note
Godkänd; 2014; 20141217 (andbra)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-06-14Bibliographically approved
Marklund, E., Asp, L. & Olsson, R. (2014). Transverse strength of unidirectional non-crimp: multiscale Modelling (ed.). Paper presented at . Composites Part B: Engineering, 65, 47-56
Open this publication in new window or tab >>Transverse strength of unidirectional non-crimp: multiscale Modelling
2014 (English)In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 65, p. 47-56Article in journal (Refereed) Published
Abstract [en]

A multiscale approach is used to predict transverse tensile and transverse compressive strength of unidirectional non-crimp fabric (NCF) composites. Numerical analysis on fibre/matrix scale is performed to obtain the transverse strength of the fibre bundle to be further used in an analytical mesoscale model to predict the strength of the unidirectional NCF composite. Design of unidirectional layer composites with the same fibres, interface, matrix and volume fractions as in the bundle is suggested as an alternative method for bundle strength determination. Good agreement of both methods for bundle transverse strength determination is demonstrated. The simple analytical model used on mesoscale gives accurate predictions of the tensile transverse strength whereas the compressive strength is underestimated. The necessity of including bundle waviness in models when bidirectional NCF composites are analyzed is demonstrated by FEM stress analysis and by experimental data showing differences in transverse cracking pattern due to bundle waviness.

National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-15962 (URN)10.1016/j.compositesb.2014.01.053 (DOI)000342870500008 ()2-s2.0-84906946467 (Scopus ID)f8c56d7f-490b-4bab-8539-c4985a4f09e0 (Local ID)f8c56d7f-490b-4bab-8539-c4985a4f09e0 (Archive number)f8c56d7f-490b-4bab-8539-c4985a4f09e0 (OAI)
Note
Validerad; 2014; 20140205 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Carlson, T. & Asp, L. (2013). An experimental study into the effect of damage on the capacitance of structural composite capacitors (ed.). Journal of Multifunctional Composites, 1(2), 91-97
Open this publication in new window or tab >>An experimental study into the effect of damage on the capacitance of structural composite capacitors
2013 (English)In: Journal of Multifunctional Composites, ISSN 2168-4246, Vol. 1, no 2, p. 91-97Article in journal (Refereed) Published
Abstract [en]

This paper presents the work to characterise the effects of tensile induced matrix cracks on capacitance of structural composite capacitor materials. The study is based on earlier work within the field of multifunctional materials where mechanical and electrical properties have been characterised. Effects of damage on electrical properties have, however, not been covered by earlier studies. The structural capacitor materials were made from carbon fibre/epoxy pre-pregs as structural electrodes with thermoplastic PET as the dielectric separator. NaOH etching was used as a route for improved adhesion between the epoxy and PET to ensure matrix cracking in the CFRP electrodes occurred prior to delamination between the electrodes and the PET separator. A method to induce and measure the effect of the matrix cracks on electrical properties was successfully developed and used in this study. The method is based on a simple tensile test and proved to be quick and easy to perform with consistent results. The structural capacitor material was found to maintain its capacitance even after significant intralaminar matrix cracking in the CFRP electrodes from high tensile mechanical loads.

National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-4799 (URN)2c8cc67a-089b-4283-ad84-6465774098be (Local ID)2c8cc67a-089b-4283-ad84-6465774098be (Archive number)2c8cc67a-089b-4283-ad84-6465774098be (OAI)
Note

Godkänd; 2013; 20131126 (leiasp)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-06-14Bibliographically approved
Asp, L. (2013). Multifunctional composite materials for energy storage in structural load paths (ed.). Paper presented at . Plastics, rubber and composites, 42(4), 144-149
Open this publication in new window or tab >>Multifunctional composite materials for energy storage in structural load paths
2013 (English)In: Plastics, rubber and composites, ISSN 1465-8011, E-ISSN 1743-2898, Vol. 42, no 4, p. 144-149Article in journal (Refereed) Published
Abstract [en]

This paper presents an overview of the research performed to date by a Swedish interdisciplinaryteam of scientists striving to develop multifunctional composite materials for storage of electric energy in mechanical load paths. To realise structural batteries from polymer composites, research pursued on carbon fibres for use as negative electrode in the battery as well as on polymer electrolytes for use as polymer matrix in the composite is reported. The work on carbon fibres comprises characterisation of the electrochemical capacity of commercial carbon fibre grades and how this is affected by mechanical load. Co-polymers are studied for their multifunctional performance with respect to lithium ion conductivity and stiffness. Also, rational processing of these polymer electrolytes and the effect of processing on their properties are addressed

National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:ltu:diva-15010 (URN)10.1179/1743289811Y.0000000043 (DOI)e77ae2d3-98c6-4800-89ad-e3dd122d73fb (Local ID)e77ae2d3-98c6-4800-89ad-e3dd122d73fb (Archive number)e77ae2d3-98c6-4800-89ad-e3dd122d73fb (OAI)
Note
Upprättat; 2013; 20130419 (leiasp)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-06-14Bibliographically approved
Leijonmarck, S., Carlson, T., Lindbergh, G., Asp, L., Maples, H. A. & Bismarck, A. (2013). Solid polymer electrolyte-coated carbon fibres for structural and novel micro batteries (ed.). Paper presented at . Composites Science And Technology, 89, 149-157
Open this publication in new window or tab >>Solid polymer electrolyte-coated carbon fibres for structural and novel micro batteries
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2013 (English)In: Composites Science And Technology, ISSN 0266-3538, E-ISSN 1879-1050, Vol. 89, p. 149-157Article in journal (Refereed) Published
Abstract [en]

We report a method to deposit a thin solid polymer electrolyte (SPE) coating around individual carbon fibres for the realisation of novel battery designs. In this study an electrocoating method is used to coat methacrylate-based solid polymer electrolytes on to carbon fibres. By this approach a dense uniform, apparently pinhole-free, poly(methoxy polyethylene glycol (350) monomethacrylate) coating with an average coating thickness of 470 nm was deposited around carbon fibres. Li-triflate, used as supporting electrolyte remained in the coating after the electrocoating operation. The Li-ion content in the solid polymer coating was found to be sufficiently high for battery applications. A battery device was built employing the SPE coated carbon fibres as negative electrode demonstrating reversible specific capacity of 260 mAh/g at low currents (C/10), suggesting that these coated carbon fibres can be employed in future structural composite batteries.

National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-6540 (URN)10.1016/j.compscitech.2013.09.026 (DOI)000328715500020 ()2-s2.0-84887014038 (Scopus ID)4c491bb0-76a9-4f77-9488-61fe6da128b7 (Local ID)4c491bb0-76a9-4f77-9488-61fe6da128b7 (Archive number)4c491bb0-76a9-4f77-9488-61fe6da128b7 (OAI)
Note
Validerad; 2013; 20131023 (andbra)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Carlson, T. & Asp, L. (2013). Structural carbon fibre composite/PET capacitors: Effects of dielectric separator thickness (ed.). Paper presented at . Composites Part B: Engineering, 49, 16-21
Open this publication in new window or tab >>Structural carbon fibre composite/PET capacitors: Effects of dielectric separator thickness
2013 (English)In: Composites Part B: Engineering, ISSN 1359-8368, E-ISSN 1879-1069, Vol. 49, p. 16-21Article in journal (Refereed) Published
Abstract [en]

This paper presents an approach towards realising novel multifunctional polymer composites with combined structural and electric energy storing ability. A series of structural capacitors were made using three thicknesses of DuPont Mylar A thermoplastic PET as a dielectric separator employing carbon fibre/epoxy pre-pregs as structural electrodes. Plasma treatment was used as a route for improved epoxy/PET adhesion. The manufactured materials were mechanically and electrically tested to evaluate their multifunctional efficiency.The multifunctional materials developed show good potential for replacing steel, aluminium and other materials with lower specific mechanical properties but do not match the high specific mechanical and electrical performance of monofunctional composites and capacitors.

National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-15577 (URN)10.1016/j.compositesb.2013.01.009 (DOI)000317444500003 ()2-s2.0-84875279858 (Scopus ID)f1c7b39b-6367-467f-a7ea-d4805cb355bf (Local ID)f1c7b39b-6367-467f-a7ea-d4805cb355bf (Archive number)f1c7b39b-6367-467f-a7ea-d4805cb355bf (OAI)
Note
Validerad; 2013; 20130228 (leiasp)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Asp, L., Szpieg, M. & Wysocki, M. (2012). Mechanical performance and modelling of a fully recycled modified CF/PP composite (ed.). Paper presented at . Journal of composite materials, 46(12), 1503-1517
Open this publication in new window or tab >>Mechanical performance and modelling of a fully recycled modified CF/PP composite
2012 (English)In: Journal of composite materials, ISSN 0021-9983, E-ISSN 1530-793X, Vol. 46, no 12, p. 1503-1517Article in journal (Refereed) Published
Abstract [en]

A fully recycled carbon fiber reinforced maleic anhydride grafted polypropylene (MAPP)-modified polypropylene (rCF/rPP) composite material has been developed and characterized. This new composite was manufactured employing papermaking principles, dispersing the recycled carbon fibers (rCF) in water, and forming them into mats. Two layers of the recycled polypropylene (rPP) films manufactured using press-forming were sandwiched between three rCF preform layers in a stack. The stack was heated and press-formed resulting in a composite plate with a nominal thickness of 1.20 mm and a fiber volume fraction of 40%. A series of tensile tests using rectangular specimens cut in four different directions (0°, 90°, ± 45°) in the composite plate were performed to confirm in-plane material isotropy. Models to predict stiffness and strength of the short fiber rCF/rPP composite were also employed and validated using experiments. The models were found to be in good agreement with experimental results. Fiber length distribution measurements were performed before (unprocessed) and after (processed) composite manufacturing to investigate the influence of processing on fiber degradation. The results revealed a significant reduction in fiber length by the press-forming operation. To model the viscoelastic and viscoplastic responses of the composite an inelastic material model was employed and characterized using a series of creep and recovery tests. From the creep tests, it was found that the time and stress dependence of viscoplastic strains follows a power law. The viscoelastic response of the composite was found to be linear in the investigated stress range. The material model was validated in constant stress rate tensile tests and the agreement was good, even close to the rupture stress.

National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-8960 (URN)10.1177/0021998311423860 (DOI)000304662300011 ()2-s2.0-84861805327 (Scopus ID)78461ad3-e273-4d71-bd22-5197a08cbc46 (Local ID)78461ad3-e273-4d71-bd22-5197a08cbc46 (Archive number)78461ad3-e273-4d71-bd22-5197a08cbc46 (OAI)
Note
Validerad; 2012; 20120601 (leiasp)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Asp, L., Marklund, E., Varna, J. & Olsson, R. (2012). Multiscale modelling of non-crimp fabric composites (ed.). In: (Ed.), (Ed.), Proceedings of the ASME International Mechanical Engineering Congress and Exposition--2012: presented at ASME 2012 International Mechanical Engineering Congress and Exposition, November 9-15, 2012 Houston, Texas USA. Paper presented at ASME 2012 International Mechanical Engineering Congress & Exposition : 09/11/2012 - 15/11/2012 (pp. 581-590). New York: American Society of Mechanical Engineers, 3
Open this publication in new window or tab >>Multiscale modelling of non-crimp fabric composites
2012 (English)In: Proceedings of the ASME International Mechanical Engineering Congress and Exposition--2012: presented at ASME 2012 International Mechanical Engineering Congress and Exposition, November 9-15, 2012 Houston, Texas USA, New York: American Society of Mechanical Engineers , 2012, Vol. 3, p. 581-590Conference paper, Published paper (Refereed)
Abstract [en]

Damage initiation and evolution in NCF composites leading to final failure includes a multitude of mechanisms and phenomena on several length scales. From an engineering point-of-view a computational scheme where all mechanisms would be explicitly addressed is too complex and time consuming. Hence, methods for macroscopic performance prediction of NCF composites, with limited input regarding micro- And mesoscale details, are requested. In this paper, multi-scale modelling approaches for in-plane transverse strength of NCF composites are outlined and discussed. In addition a simplistic method to predict transverse tensile and compressive strength for textile composites featuring low or no fibre waviness is presented

Place, publisher, year, edition, pages
New York: American Society of Mechanical Engineers, 2012
National Category
Composite Science and Engineering
Research subject
Polymeric Composite Materials
Identifiers
urn:nbn:se:ltu:diva-38571 (URN)10.1115/IMECE2012-89236 (DOI)2-s2.0-84887286420 (Scopus ID)d01f2e2c-f001-4051-b173-a4bebb599d30 (Local ID)9780791845196 (ISBN)d01f2e2c-f001-4051-b173-a4bebb599d30 (Archive number)d01f2e2c-f001-4051-b173-a4bebb599d30 (OAI)
Conference
ASME 2012 International Mechanical Engineering Congress & Exposition : 09/11/2012 - 15/11/2012
Note
Godkänd; 2012; 20131125 (andbra)Available from: 2016-10-03 Created: 2016-10-03 Last updated: 2018-07-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-0630-2037

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