Fibre-reinforced composites structures

Savage G. Enhancing the exploitation and efficiency of fibre-reinforced composite structures by improvement of interlaminar fracture toughness. Eng Fail Anal 2006 13 198—209. http //dx.doi.Org/10.1016/j.engfailanal.2004.12.047. 

Bisagni C, Dipietro G, Fraschini L, Terletti D. Progressive crushing of fibre-reinforced composite structural components of a formula one racing car. Compos Struct 2005 68 491-503. 

Fig. 26.3. The molecular structure of a cell wall. It is a fibre-reinforced composite (cellulose fibres in o matrix of hemicellulose and lignin).

Polymer materials are frequently used under stress loadings and these may be concentrated at certain parts of the structure. Thermal stresses may be induced by non-uniform heating or by differential expansion coefficients the latter may be an important factor in the degradation of fibre-reinforced composites in the radiation environment of space. 

Fibre Bragg grating sensors are a type of optical sensor that has received considerable attention in recent years. They are used for monitoring the structural condition of fibre-reinforced composites, concrete constructions or other construction materials. 

Thermal residual stresses are inherent to fibre reinforced composites due to the heterogeneity of the thermo-mechanical properties of their two constituents. Such stresses build up when composite structures are cooled down from the processing temperature to the test temperature. Residual stresses will be present on both a fibre-matrix scale (micro-scale), and on a ply-to-ply scale (macro-scale) in laminates built up from layers with different orientations. It is recognised that these stresses should be taken into account in any stress analysis. 

Yahya MY, Cantwell WJ, Langdon GS, Nurick GN. The blast behaviour of fibre reinforced composite materials. In Proc. 7th international conference on shock and impact loans on structures 2007. pp. 691—8. 

Yahya MY. The blast response of fibre reinforced composites and sandwich structures. [Ph.D. thesis]. University of Liverpool 2008. 

Impact behaviour of fibre-reinforced composite materials and structures... 

Textile structures are not just limited to the apparel sector they have moved into equipment as well, especially with composite structures such as carbon fibre reinforced composites and novel textile construction. Methods such as 3D weaving and tailored fibre placement have meant that complex structures can be manufactured with specific geometry and physical properties. 

Fibrous composites are a relatively new technology and there are too many material and structural variables to discuss fully all the details of their mechanical behaviour. Therefore, the present chapter will concentrate on certain categories of fibre reinforced composites, all with polymer matrix systems. 

L G P Dalmolen, J Willing, A Goksoyr and P Osen, Para-aramid fibre-reinforced composite bellmouths for a floating production platform . Conference on Structural Materials in Marine Environments, London, loM/MTD/IMechE/ IMarE, 11-12 May 1994, pp 109-118. 

Epoxidised allyl soyate resin (a mixture of epoxidised fatty acid esters) copolymerised with the base Shell Epon epoxy resin is used as matrix for glass fibre reinforced composite, which is prepared using a Durapul 6000 Labstar Pultrusion machine. The lubricating quality of soybean oil-based resin significantly reduces the pulling force which improves the structural performance characteristics of the composites. Curing is carried out in an oven at 80°C for one hour, followed by heating to 177 C for 1.5 h. 

As with aluminium extrusions, so with pultruded fibre reinforced composite profiles. The limit to the size and complexity of these profiles suggests that a modular approach could be adopted towards forming alternative structural configurations from the basic or standard profile shapes by bonding together individual lengths. Composite materials lend themselves to being joined with resin adhesives because they are themselves formed with vinyl ester, polyester or epoxy resins. Cursory surface treatments only, such as mild abrasion, often suffice. 

About 30% of all polymers produced each year are used in the civil engineering and building industries(23). Nevertheless, structural plastics such as fibre reinforced composites have so far received little attention by civil and structural engineers, despite some of their obvious advantages such as lightness, handleability and corrosion resistance. This may be due to reservations on credibility grounds or fire resistance properties, as well as to uncertainty on how to design structures with them. Whilst their mechanical properties are in fact fairly well understood, there are a number of... 

Characteristic material properties for fibre reinforced composites cannot be so rigorously defined as for most other structural materials. Standard data are either not generally available or cannot be relied upon except for preliminary design. Because of its nonhomogeneity and anisotropy, up to 21 elastic constants may, in theory, be required for a full analysis of a complex laminate. In practice though, due to symmetry, these reduce to ... 

Moy SSJ, Barnes F, Moriarty J, Dier AF, Kenchington A, Iverson B, Structural upgrade and life extension of cast iron struts using carbon fibre reinforced composites, FRC2000 Conference, Newcastle, Sep 13-14 2000. 

Natural fibres possess sufficient strength and stiffiiess but are difficult to use in load bearing applications by themselves because of their fibrous structure. Most plastics themselves are not suitable for load bearing applications due to their lack of sufficient strength, stiffness and dimensional stability [51]. In natural fibre reinforced composites, the fibres serve as reinforcement by giving strength and stiffness to the structure while the plastic matrix serve as the adhesive to hold the fibres in place so that suitable structural components can be made. The matrix for the natural fibres includes thermosets, thermoplastics and mbber. Different plant fibres and wood fibres are fotmd to be interesting reinforcements for rubber, thermoplastics and thermosets [52-58]. 

The chapter demonstrates that in spite of the incompatibility between hydrophilic natural fibres and hydrophobic polymeric matrices, the properties of natural fibre composites can be enhanced through chemical modifications. The chemical treatments have therefore played a key role in the increased applications of natural fibre composites in the automotive sector. Recent work has also shown that if some of the drawbacks of natural fibres can be adequately addressed, these materials can easily replace glass fibres in many applications. The chapter has also shown that there have been attempts to use natural fibre composites in structural applications, an area which has been hitherto the reserve of synthetic fibres like glass and aramid. The use of polymer nanocomposites in applications of natural fibre-reinforced composites, though at infancy, may provide means to address these efficiencies. Evidence-based life-cycle assessment of natural fibre-reinforced composites is required to build confidence in the green composites applications in automotive sector. 

Cellulosic and acrylic fibres, which are spun from solution, show granular breaks, which are similar to lower-magnification views of the structure of a fibre-reinforced composite, Fig. 5a,b. The reasons are similar. The fibres coagulate from solution with... 

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