Hybrid fibre systems

The combination of two or more types of fibres (hybrid reinforcement) has been studied and applied with the objective of optimizing the overall system to achieve 

Hybrids based on fibre constitutive response, where one fibre is stronger and stiffer and provides strength, while the other is more ductile or can readily undergo considerable slippage to provide toughness at high strains and crack openings. 

Hybrids based on fibre function where one type of fibre (the primary fibre) induces strength or toughness in the hardened composite, while the second type of fibre provides the fresh mix properties suitable for processing (the processing fibre). 

The hybrid can thus be made of fibres of different properties, or having different shapes. 

Earlier studies and publications addressed hybrid systems for applications in thin sheet composites, in particular for asbestos-cement replacements. In recent years the concept has been extended for high performance-high ductility FRC, which can be produced by simple mixing. 

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Hybrid fibre systems in thin sheet composites... 

The systems described earlier, used a hybrid steel fibre system, consisting of meso and macrofibres. Systems in which the smaller fibre in the hybrid reinforcement was a microfibre were reported in several studies [116-118]. The microfibres were in most cases of a different composition than the macrofibre (usually steel). The microfibres evaluated were alumina [116], carbon [116,117], PVA [117,118], ultra high density polyethylene [117,118] and steel [117]. The characteristics of such fibres are presented in Table 12,7,... 

Polypropylene homopolymer (PP) is a widely used thermoplastic material, despite its brittle behaviour at either low temperature or high loading rates. Improvement in the fi acture toughness of PP can be achieved by either modifying the crystalline structure, or addition of a second phase material [16], The toughening effect and mechanisms of different second phase materials such as stiff fibres, soft rubbery inclusions (EPR, EPDM), and some mineral fillers have been analysed. Recent developments concern the effect of hybrid system consisting of rigid and rubbery inclusions. 

A DNA optical sensor system was proposed by Cass and co-workers [35] based on the combination of sandwich solution hybridization, magnetic bead capture, flow injection and chemiluminescence for the rapid detection of DNA hybridization. Sandwich solution hybridization uses two sets of DNA probes, one labelled with biotin, the other with an enzyme marker and hybridization is performed in solution where the mobility is greater and the hybridization process is faster, rather than on a surface. The hybrids were bound to the streptavidin-coated magnetic beads through biotin-streptavidin binding reaction. A chemiluminescence fibre-optic biosensor for the detection of hybridization of horseradish peroxidase-labelled complementary DNA to covalent immobilized DNA probes was developed by Zhou and co-workers [36]. 

In this chapter, the characteristics of air explosions are briefly described and various blast protection paradigms are discussed. The blast behaviour of plain composites and multilayered structures are then discussed. Plain composites typically comprise polymeric resins with a fibre reinforcement, such as carbon fibre-reinforced epoxy resins. Multilayered systems include composite sandwich stmctures and hybrid composite-metal structures, known as fibre-metal laminates (FMLs). 

Of course, there are many more possibilities than the examples shown. They just focus on the theme in general and may be helpful for the discussion of future building systems. Other examples of materials include pneumatic systems or even fibre-reinforced materials, hybrid materials that combine different elements for additional functions. In the future, for example, windows may be used not only to obtain daylight, but also as solar collectors, as media fagades, and as flexible fagades with different properties for summer and winter. 

The conventional ring spinning system can be used only with a staple fibre. By slightly modifying the conventional system, it can be used to manufacture hybrid yams, such as core spun yams. - ... 

Expansion of the hybridization between metals and eomposites has led to a re-examination of the role of metals in helmet systems. As expressed earlier, metals (namely steel) had been the armour material of ehoiee before the development of high-tenacity fibres. Since then, steel has been discarded from helmet material selection. While some have explored the rrse of alirminiirm, magnesium and titanium shells, the general performance gains were not substantial enough to justify the subsequent processing and interfacing, whilst concerns were also raised about their durability (Walsh et ai, 2008). 

Hybrid—A composite laminate comprised of laminae of two or more composite material systems. Or, a combination of two or more different fibres into a structure. 

The incorporation of nanoclays and natural fibres in resin systems thus provides reinforcements to resin systems at two scales. The nanoclay enhances the bio-based polymer system in stiffiiess and hygrothermal properties, while the natural fibres provide the main stiffness and strength. In addition, the enhanced barrier properties of the nano-reinforced resin retard moisture from reaching the natural fibres and thereby providing a synergetic effect between scales for an efficient bio-based composite. Hybrid bio-based composites that exploit the synergy between natural fibres (industrial hemp) in a nano-reinforced bio-based polymer can lead to... 

Gotzmann [60] discusses methods used in the manufacture of metal plastic hybrid components such as glass fibre reinforced PA around a steel or aluminium profile placed in the mould used for injection moulding plastics. Some applications of such components were examined, and computer aided materials selection, finite element analysis and computer simulation systems developed for use in this technology are described. 

Hybrid composite materials (HCM) represent the newest group of various composites where more than one type of fibre is used to increase cost-performance effectiveness, i.e., in a composite system reinforced with carbon fibres the cost can be minimised by reducing its content while maximising the performance by optimal partial replacement with an another fibre or by changing the orientations. HCM include nanocomposites [31], functionally gradient materials [32], Hymats (hybrid materials) [33], interpenetrating polymer networks (IPN) [34], and liquid crystal polymers [35]. 

Another novel pultruded panel has been developed by Mastercore System Ltd., Canada. This could be used in applications such as truck walls, roofs, floors and doors, boat decks, freight containers and sound barriers. The mastercore panel consists of an outer shell of a polyurethane-impregnated fibre carbon/glass fibre hybrid composites with an inner core of a structural foam (Jacob, 2006). 

Abstract Fibre-reinforced polymer (FRP) composites have become essential materials for maintaining and strengthening existing infrastructure. Many new innovative types of hybrid material and structural systems have been developed using FRP composite materials. Increased utilisation of FRP requires that structural engineers and practitioners be able to understand the behaviour of FRP materials and design composite structures. This book provides an overview of different advanced FRP composites and the use of these materials in a variety of application areas. This chapter specifically covers a brief review on FRP applications and gives an outline of the book. 

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