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Viscous flow of aligned composites


The case is considered of an aligned composite subjected to tensile creep in the direction of the fibres. A geometrical argument shows that shear strain in the composite is amplified l/2s times compared with unsupported matrix, where l/2s ∼ aspect ratio of the inter-fibre spaces. The shear stress is amplified (l/2s)1/n times, where n is the exponent in the matrix creep law. Consequently the rate of energy expenditure is amplified V m(1/2s)1+1/n times, as is therefore the tensile flow resistance of the composite (V m is the volume fraction of matrix). The potential increase in flow resistance is thus enormous. However, the fibre end-stress, which is calculated, ∝ fibre diameter, and may be large enough to initiate rupture unless the fibres are very thin (e.g. 1 μm diameter). The tensile load is roughly equally divided between matrix and fibres irrespective of volume fractions.

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McLean, D. Viscous flow of aligned composites. J Mater Sci 7, 98–104 (1972).

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  • Polymer
  • Shear Stress
  • Energy Expenditure
  • Aspect Ratio
  • Shear Strain