Aligned fibre composites glass fibres

The extmsion of viscous glass/reinforcement mixtures has also been considered to produce glass matrix composites. This process is shown schematically in Figure 5. It has been applied to the fabrication of composites with aligned chopped SiC-fibre and C-fibre [30] as well as SiC-platelet [42] and alumina platelet [119]. The technique enables the fabrication of components with large length-to-diameter ratios. 

A composite material consists of 40% (l volume) continuous, uniaxially aligned, glass fibres in a matrix of thermoset polyester. A tensile stress of 100 MPa is to be applied parallel to the fibres. Predict the strains which will result. Take the tensile modulus and Poisson s ratio of glass to be 76 GPa and 0.22, and of thermoset polyester to be 3 GPa and 0.38, respectively. 

A composite material consists of 55% (by volume) continuous, uniaxially aligned, S-glass fibres in a matrix of epoi. Such a composite is found to have a tensile strength transverse to the fibres a- = 25 MPa and shear strength parallel to the fibres t 2 = 55 MPa. The tensile strength and modulus of the fibres are 1900 MPa and 86 GPa, and of the matrix are 60 MPa and 2.4 GPa, respectively. The composite is to be subjected to tensile stress in a direction inclined at 2(P to the iSbre axes. Predict the stress at failure and determine the mode of failure. 

The fibres in short fibre composites are not usually fiilly aligned. An early attempt to deal with such systems was made by Brody and Ward [12], who applied the aggregate model of Section 7.5 above assuming that the elastic constants of a representative unit of structure could be predicted by Equations (8.7a)-(8.7e). It was found that this simple theory fitted the results for composites reinforced with short fibres of carbon or glass reasonably well, with the moduli lying close to the lower Reuss bounds. Recent studies by Ward and co-workers [13] have shown that this approach is viable provided that the elastic constants of the representative unit are calculated more exactly. 

A composite material consists of 60 % (by volume) continuous, uniaxially aligned, glass fibres in a matrix of epoxy. A tensile stress of ISO MPa is applied in a direction inclined... 

A single ply glass/epoxy composite has the properties Usted below. If the fibres are aligned at 30° to the x-direction, determine the value of in-plane stresses, a, which would cause failure according to (a) the Maximum Stress criterion (b) the Maximum Strain criterion and (c) the Tsai-Hill criterion. 

The mean fibre length determines the fibre aspect ratio. One theory considers the effects of inclusions, of a given aspect ratio, surrounded by a material with the average properties of the composite. Figure 4.29a shows predictions for E-glass inclusions ( = 73GPa, p = 0.22) in an epoxy matrix (E = 5.35 GPa, v = 0.34) there is a steady increase in the composite modulus Ell in the direction of the perfectly aligned inclusions, as the aspect ratio and the fibre volume fraction increase. 

The first two groups of parameters are considered by the designer who decides on the material s structure and composition. As described in Section 5.4, steel fibres are used as short chopped lengths, as continuous woven wires, non-woven or welded at the nodes (ferrocement) and as a kind of wool composed of thin and long entangled wires. Short fibres are, in most cases, randomly distributed, but their alignment is also possible. Glass and other kinds of fibres may be also chopped or used in the form of mats and fabrics. 

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