Fibre-reinforced composites methods

PPG in its Introduction to glass fibre reinforced composites proposes a calculation method for the strength estimate based on four principles ... 

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. 

However, lack of good interfacial adhesion, low melting point, and poor resistance towards moisture make the use of natural fibre-reinforced composites less attractive. Pre-treatments of the natural fibre can clean the fibre surface, chemically modify the surface, stop the moisture absorption process and increase the surface roughness. Among the various pre-treatment techniques, graft copolymerization and plasma treatment are the best methods for surface modification of natural fibres. Graft copolymers of natural fibres with vinyl monomers provide better adhesion between matrix and fibre. 

Contact moulding is a simple and well known method for fabrication of fibre-reinforced thermoset composites. Thermoset resins which cure at room temperature such as unsaturated polyester, vinyl ester, and epoxy are used to make glass, jute or carbon fibre-reinforced composites using contact moulding. A wide variety of structures can be fabricated using this technique without limitation with respect to the size and complexity of the shape of the structure. However, the process is very labour-intensive and time-consuming, so is used only for a short run or one-off production. 

There are a number of published papers in the area of composites, probably exceeding those in the area of textiles themselves examples of a few recent pubUcations on the application of the homogenization method in modelling the mechanical properties of fibre-reinforced composites are Saidpour and Oscar (2006), Maimi et aL (2008), Massart et al (2011), and Melro et al. (2012). 

It is clear that this present study introduces a new method of following the micromechanics of fibre-reinforced composites. The ability to measure the strain at a point in an individual fibre should lead to a significant increase in our understanding of the deformation of these important materials and of fibre/matrix interactions. 

Murakami, S., Manabe, K., Miyao, M., Enomoto, M., Ishida, Y. and Inoue, H. (Toa Nenryo Kogyo Kabushiki Kaisha) (1994), Carbon fibre-reinforced composite resin pultrusion products and method of manufacturing the same, EP0308237 Bl, 10 August 1994. 

Abstract This chapter describes the elastic qualities of advanced fibre-reinforced composites, in terms of characterization, measurement and prediction from the basic constituents, i.e. the fibre and matrix. The elastic analysis comprises applying micromechanics approaches to predict the lamina elastic properties from the basic constituents, and using classical lamination theory to predict the elastic properties of composite materials composed of several laminae stacked at different orientations. Examples are given to illustrate the theoretical analysis and give a full apprehension of its prediction capability. The last section provides an overview on identification methods for elastic proprieties based on full-field measurements. It is shown that these methodologies are very convenient for elastic characterization of anisotropic and heterogeneous materials. 

In the case of fibre reinforced composites a special measure of workability was proposed by ACI 544.2R-89 called inverted slump cone. A standard Abrams cone is suspended upside down and filled with tested material without any compaction. The internal vibrator is activated and the bottom cover of the cone is removed, then the time of flow out of the material is recorded, which is usually between 10 and 30 seconds. This method is still in use, but is subject to some criticisms. Other methods of the flowability of the fresh mix with dispersed fibres are proposed by Laboratoire des Fonts et Chaussees in France (cf. Section 12.5). 

A different method of creating UHMWPE fibre-reinforced UHMWPE composites was presented by Mosleh et al. [179]. In this method, dry UHMWPE powder was mechanically oscillated through a funnel onto subsequent layers of short (25 mm) chopped UHMWPE fibres, or pieces of continuous UHMWPE fabric. By repeating this process with many layers of short chopped UHMWPE fibres or UHMWPE fabric, a layered stmcture was reported to have been created. These fibre assemblies were then heated under pressure to consolidate the structures. The short UHMWPE fibre-reinforced composites had a fibre volume fraction between 25 and 75%, while the continuous UHMWPE fabric-reinforced composites had a fibre volume fraction of 60%. Investigations into the potential application of these homocomposites in an articulation surface for a knee joint prosthesis were also described, as were the challenges associated with measuring the tribological performance of such fibre-reinforced materials [180]. 

Polymer materials studied by CLSM have included fibre-reinforced composites, where a transparent epoxy resin matrix allowed internal interfaces to be seen [117], and latex suspensions [119]. Clarke et al. [120] explored the maximum usable depth of scanning laser confocal imaging, comparing fibre orientation measurements of fibre-reinforced composites by both reflected light and confocal methods. 

Abstract. This chapter is concerned with an in-depth examination of the adherend surface pretreatments used prior to structural adhesive bonding. It encompasses the various substrates encountered, particularly but not exclusively, in the aerospace industry. It compares and contrasts mechanical, chemical and electrochemical methods used for substrates comprising aluminium alloys, titanium, stainless steel, thermoplastic and thermoset fibre reinforced composites and non-metallic honeycomb. Scanning and transmission electron microscope techniques are used to analyse and characterise many of the pretreated surfaces so produced. 

A pyrolysis technique was investigated as a method for the chemical recycling of glass fibre-reinforced unsaturated polyester SMC composites. The proeess yielded liquid products and gases and also a solid residue formed in the pyrolysis of glass fibres and fillers. The solid residue was used as a reinforeement/filler in unsaturated polyester BMC composites, and the influenee on mechanical properties was studied in comparison with BMC prepared entirely from virgin materials. 

ISO 14129 1997 Fibre-reinforced plastic composites - Determination of the in-plane shear stress/shear strain response, including the in-plane shear modulus and strength, by the plus or minus 45 degree tension test method... 

ISO 14130 1997 Fibre-reinforced plastic composites - Determination of apparent interlaminar shear strength by short-beam method ISO 15024 2001 Fibre-reinforced plastic composites - Determination of mode I interlaminar fracture toughness, GIC, for unidirectionally reinforced materials... 

Methods for manufacturing different fibre-reinforced glass/glass-ceramic matrix composites... 

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