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Flexible Composites - Strength, Deformation and Fracture Proecesses in Woven and D.O.S. Reinforcement Materials

Dartman, Torbjörn LU (2002)
Abstract (Swedish)
Popular Abstract in Swedish

Teknisk textil är en bred benämning för textila material med användningsområden som inte är beklädnad eller där utseendemässiga krav oftast är av underordnad betydelse. På senare tid har dock designsynpunkter på tekniska textilprodukter kommit att alltmer uppmärksammas och detta belyses i kapitel 10 i avhandlingen. Teknisk textil är en nygammal industrigren som genomgått en kraftig expansion under de senaste decennierna, en expansion som inte har avmattats. Teknisk textil kommer att ta en allt större marknadsandel av den totala textilkonsumtionen och ligger nu på nivåer runt 30 %. Exempel på tekniska textilprodukter är krockkuddar (airbags), ljudisolerande väggar, maskinfilt, oljefångande mattor,... (More)
Popular Abstract in Swedish

Teknisk textil är en bred benämning för textila material med användningsområden som inte är beklädnad eller där utseendemässiga krav oftast är av underordnad betydelse. På senare tid har dock designsynpunkter på tekniska textilprodukter kommit att alltmer uppmärksammas och detta belyses i kapitel 10 i avhandlingen. Teknisk textil är en nygammal industrigren som genomgått en kraftig expansion under de senaste decennierna, en expansion som inte har avmattats. Teknisk textil kommer att ta en allt större marknadsandel av den totala textilkonsumtionen och ligger nu på nivåer runt 30 %. Exempel på tekniska textilprodukter är krockkuddar (airbags), ljudisolerande väggar, maskinfilt, oljefångande mattor, kamouflagenät, skyddsvästar, filter. En bidragande orsak till att användningen av teknisk textil ökat är utvecklingen av nya högpresterande fibermaterial (aramider, kolfibrer) och nya avancerade metoder för framställning av vävda, stickade och flätade produkter.



En viktig materialklass inom teknisk textil är flexibla och semi-flexibla kompositer. Belagd duk är exempel på ett flexibelt komposit material och transportband på ett semi-flexibelt vars mekaniska egenskaper som töjning och böjstyvhet ligger mellan flexibla och hårda kompositer. Nya material baserade på DOS strukturer uppmärksammas speciellt. DOS = Direct Oriented Structures är varptrikå med varp- och/eller väft inslag.



I avhandlingen kapitel 1 definieras olika klasser av kompositmaterial och mekaniska egenskaper hos dessa och ingående komponenter som bärare och matrismaterial. Syftet med avhandlingen är att · identifiera en kedja mellan egenskaper hos de ingående materialen som fiber, garn, duk, matris och av dessa uppbyggda kompositmaterial; · undersöka och utvärdera metoder för karakterisering av mekaniska egenskaper hos fibrer, garn, duk och flexibla eller semi-flexibla kompositer; · analysera kriterier för hållfasthet, deformation och brottmekanismer för flexibla kompositer; · presentera några nya idéer för applikationer där kompositer kan användas.



Avhandlingen är en sammanläggning av artiklar publicerade i olika vetenskapliga tidskrifter och föredrag presenterade vid symposier och konferenser. Avhandlingen är uppdelad i 12 kapitel med ett inledande kapitel och ett avslutande med litteraturreferenser . (Less)
Abstract
In this thesis the tensile strength, deformation, damage resistance and tear propagation for flexible composites are analysed. There are two essential requirements common to all flexible composites; namely, high tearing strength and good matrix-to-fabric adhesion. The interaction of fabric and matrix is complex. The most critical variables are those of yarn and fabric structure, the mechanical properties of the matrix, the adhesion of fibre-matrix interface and the penetration of the matrix into spun and multifilament yarns. Coated fabrics are an important class of flexible composites and mechanical properties and testing methods for such materials are emphasised in the thesis.



The effect of used yarns and fabric... (More)
In this thesis the tensile strength, deformation, damage resistance and tear propagation for flexible composites are analysed. There are two essential requirements common to all flexible composites; namely, high tearing strength and good matrix-to-fabric adhesion. The interaction of fabric and matrix is complex. The most critical variables are those of yarn and fabric structure, the mechanical properties of the matrix, the adhesion of fibre-matrix interface and the penetration of the matrix into spun and multifilament yarns. Coated fabrics are an important class of flexible composites and mechanical properties and testing methods for such materials are emphasised in the thesis.



The effect of used yarns and fabric structures has been analysed. Two distinct failure and crack-propagation mechanisms in flexible composites have been analysed: ductile and brittle failure. Four different ways for the crack to propagate have been identified for coated D.O.S.-fabrics (D.O.S. = Direct Oriented Structures). Tongue tear test methods are sufficient for evaluation of tear strength, not only for coated woven materials, but also for coated D.O.S. materials, if a higher rate of extension, use of capstan clamps and detailed expression of the test result is permitted in the test methods.



There is a need to introduce new analysis methods for evaluating the mechanical properties of all the novel kinds of flexible materials that have appeared on the market during recent decades. Examples are D.O.S. materials for reinforcement and use of co-mingled yarns as a matrix material. New test methods are introduced for evaluating damage resistance and crack propagation.



The rule of mixture (ROM) can be used as a first approximation of the tensile behaviour of textile-based flexible composites if the thermo-mechanical history of the fibre and matrix properties is taken into account. The ROM is usually used for rigid composites, but can also be a tool for evaluating the tensile properties of semi-flexible composites, which are defined as an intermediate between the rigid and flexible composites with at least some feature of the flexible composites incorporated, providing non-catastrophic large-strain behaviour. The mechanical properties of D.O.S. materials can be similar to those of semi-flexible composites.



Studies on joint strength of PVC-coated polyester or nylon fabrics with different levels of adhesion, including peel and lap joints, have been carried out. Examples of applications are given, such as the use of decorative textiles in composites for appearance as well as for improved impact resistance. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Professor Rychwalski, Rodney, Edebacken 11, SE-41728 Göteborg
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Kompositmaterial, Composite materials, Textile materials, Joints, Coated fabrics, Tear strength, Flexible composites, Damage resistance
pages
245 pages
publisher
Mechanical Engineering, Box 118, SE-22100 LUND,
defense location
Sal M:E M-huset, Ole Römers väg 1, Lunds Tekniska Högskola
defense date
2002-11-29 13:15
external identifiers
  • Other:ISRN:LUTMDN/(TMMV-1055)/1-245/2002
ISBN
91-628-5426-7
language
English
LU publication?
yes
id
f94b17ed-c32d-40fb-96fa-df1a66253144 (old id 465248)
date added to LUP
2007-09-06 13:51:30
date last changed
2016-09-19 08:45:07
@misc{f94b17ed-c32d-40fb-96fa-df1a66253144,
  abstract     = {In this thesis the tensile strength, deformation, damage resistance and tear propagation for flexible composites are analysed. There are two essential requirements common to all flexible composites; namely, high tearing strength and good matrix-to-fabric adhesion. The interaction of fabric and matrix is complex. The most critical variables are those of yarn and fabric structure, the mechanical properties of the matrix, the adhesion of fibre-matrix interface and the penetration of the matrix into spun and multifilament yarns. Coated fabrics are an important class of flexible composites and mechanical properties and testing methods for such materials are emphasised in the thesis.<br/><br>
<br/><br>
The effect of used yarns and fabric structures has been analysed. Two distinct failure and crack-propagation mechanisms in flexible composites have been analysed: ductile and brittle failure. Four different ways for the crack to propagate have been identified for coated D.O.S.-fabrics (D.O.S. = Direct Oriented Structures). Tongue tear test methods are sufficient for evaluation of tear strength, not only for coated woven materials, but also for coated D.O.S. materials, if a higher rate of extension, use of capstan clamps and detailed expression of the test result is permitted in the test methods.<br/><br>
<br/><br>
There is a need to introduce new analysis methods for evaluating the mechanical properties of all the novel kinds of flexible materials that have appeared on the market during recent decades. Examples are D.O.S. materials for reinforcement and use of co-mingled yarns as a matrix material. New test methods are introduced for evaluating damage resistance and crack propagation.<br/><br>
<br/><br>
The rule of mixture (ROM) can be used as a first approximation of the tensile behaviour of textile-based flexible composites if the thermo-mechanical history of the fibre and matrix properties is taken into account. The ROM is usually used for rigid composites, but can also be a tool for evaluating the tensile properties of semi-flexible composites, which are defined as an intermediate between the rigid and flexible composites with at least some feature of the flexible composites incorporated, providing non-catastrophic large-strain behaviour. The mechanical properties of D.O.S. materials can be similar to those of semi-flexible composites.<br/><br>
<br/><br>
Studies on joint strength of PVC-coated polyester or nylon fabrics with different levels of adhesion, including peel and lap joints, have been carried out. Examples of applications are given, such as the use of decorative textiles in composites for appearance as well as for improved impact resistance.},
  author       = {Dartman, Torbjörn},
  isbn         = {91-628-5426-7},
  keyword      = {Kompositmaterial,Composite materials,Textile materials,Joints,Coated fabrics,Tear strength,Flexible composites,Damage resistance},
  language     = {eng},
  pages        = {245},
  publisher    = {ARRAY(0xa329548)},
  title        = {Flexible Composites - Strength, Deformation and Fracture Proecesses in Woven and D.O.S. Reinforcement Materials},
  year         = {2002},
}