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Strength distribution of a unidirectional fibre composite
transverse crack have been identified. A tensile fracture criterion is developed in which the notch sensitivity is related to the properties of the fibre, matrix and fibre/matrix interface. The effect of notch size on the failure stress is predicted and compared with experimental data. Strength distribution of a unidirectional fibre composite Sun, C.T. and Yamada, S.E.Journal of Composite Materials Vol 12 (April 1978) pp 169-176 Three existing strength criteria for composite materials have been extended to account for the statistical behaviour of the uts of glass/epoxy composites. The basic distribution functions for the longitudinal, transverse and in-plane shear strengths were obtained by fitting the experimental data into a two-parameter Weibull distribution. These three functions were then used to predict the strength distribution of the composite under off-axis loads. Theoretical and experimental
results were compared and discussed, Thermal expansion coefficients of unidirectional composites Ishikawa, T., Koyama, K. and Kobayashi, S.H. Journal of Composite Materials Vo112 (April 1978) pp 153-168 The thermal expansion coefficients of several unidirectional carbon fibre/epoxy composites are measured using an interferometric dilatometer. The results are compared with an analytical model which is a modified form of the model developed by the authors for calculating elastic moduli of composites. The importance of fibre anistropy and temperature dependence of the expansion coefficient of the epoxy matrix are considered, The torsional creep of carbon fibre reinforced epoxide resins Hancox, N.L. and Minty, D.C.C. Journal of Materials Science Vol 13 (1978) pp 797-806 The torsional creep behaviour of
unidirectional cfrp has been studied as a function of temperature and resin/hardener ratio. The lowest creep rates are reported for stoichiometric mixes of resin and hardener receiving the maximum cure. The reinforced specimens showed a much lower secondary creep rate than the resin alone. An activiation energy of 5 to 6.3 kcal/(gmol) is deduced for the material receiving a preload of 40% of ultimate. Transverse impact of ideal fibre-reinforced rigid-plastic plates Shaw, L. and Spencer, A.J.M.
Proceedings o f the Royal Society o f London Vol A 361 (1978) pp 43-64 A simple model of a plate of ductile material reinforced in two or more directions by strong fibres is constructed on the assumptions that the plate has rigid-plastic behaviour and is inextensible in the fibre directions. The shear deformation during transverse impact of a large plate is analysed and the theory extended to include circular and rectangular plates.
Abstracts of patents Abstracts of British Patents are prepared by Dr F.R. Jones, Department of Metallurgy, University of Surrey, Guildford
Method and apparatus for conversion of attenuable materials into fibres Saint-Gobain Industries) Br Pat 513
060 (June 1978) A method is described for the production of fibres from glass or slag. Improvements in or relating to reinforced plastics articles (Fiber Science Inc)BrPatl 513829 (14 June 1978) A filament wound cyclinder from which the end-plates can be removed, can be placed in a mould and cured thereby producing a hollow object. Improvements in or relating to the construction of boats, ships and the like having resin bonded fibre hulls (Alsamex (Products) Ltd), Br Pat 1 514 523 (14 June 1978)
COMPOSITES
. JANUARY
1979
A method of forming a structural stiffening rib on a curved resin/glass fibre shell using a plastics foam (eg polyethylene) is described.
H o s e - r e i n f o r c e d with discontinuous fibers oriented in the radial direction (Monsanto Co) Br Pat 1 514 620
(14 June 1978) An extrudable composite when forced through a channel of correct geometry enables the fibres to be radially oriented. These dimensions are described, Improvements in or relating to the manufacture of porous carbon bodies ( U K A E A ) Br Pat 1 514 171 (14
June 1978) A porous a) carbon or b) silicon
carbide network is produced by melt oppining petroleum pitch containing either a) 10% AI20a particles or b) 30-40% Si, allowing the fibres to partially stick together before oxidation and carbonisation. The application is porous electrical resistance heaters.
Improvements in or relating to fibre-reinforced composites ( N R D C ) Br Pat 1,514 239 (14 June
1978)
A glass fibre reinforced cement/cenospheres material is described. The cenospheres are a small proportion of pulverised fuel ash, but are used in the composite at a loading of at least 30%. A monomer impregnated version which can be heat cured is also described.
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results were compared and discussed, Thermal expansion coefficients of unidirectional composites Ishikawa, T., Koyama, K. and Kobayashi, S.H. Journal of Composite Materials Vo112 (April 1978) pp 153-168 The thermal expansion coefficients of several unidirectional carbon fibre/epoxy composites are measured using an interferometric dilatometer. The results are compared with an analytical model which is a modified form of the model developed by the authors for calculating elastic moduli of composites. The importance of fibre anistropy and temperature dependence of the expansion coefficient of the epoxy matrix are considered, The torsional creep of carbon fibre reinforced epoxide resins Hancox, N.L. and Minty, D.C.C. Journal of Materials Science Vol 13 (1978) pp 797-806 The torsional creep behaviour of
unidirectional cfrp has been studied as a function of temperature and resin/hardener ratio. The lowest creep rates are reported for stoichiometric mixes of resin and hardener receiving the maximum cure. The reinforced specimens showed a much lower secondary creep rate than the resin alone. An activiation energy of 5 to 6.3 kcal/(gmol) is deduced for the material receiving a preload of 40% of ultimate. Transverse impact of ideal fibre-reinforced rigid-plastic plates Shaw, L. and Spencer, A.J.M.
Proceedings o f the Royal Society o f London Vol A 361 (1978) pp 43-64 A simple model of a plate of ductile material reinforced in two or more directions by strong fibres is constructed on the assumptions that the plate has rigid-plastic behaviour and is inextensible in the fibre directions. The shear deformation during transverse impact of a large plate is analysed and the theory extended to include circular and rectangular plates.
Abstracts of patents Abstracts of British Patents are prepared by Dr F.R. Jones, Department of Metallurgy, University of Surrey, Guildford
Method and apparatus for conversion of attenuable materials into fibres Saint-Gobain Industries) Br Pat 513
060 (June 1978) A method is described for the production of fibres from glass or slag. Improvements in or relating to reinforced plastics articles (Fiber Science Inc)BrPatl 513829 (14 June 1978) A filament wound cyclinder from which the end-plates can be removed, can be placed in a mould and cured thereby producing a hollow object. Improvements in or relating to the construction of boats, ships and the like having resin bonded fibre hulls (Alsamex (Products) Ltd), Br Pat 1 514 523 (14 June 1978)
COMPOSITES
. JANUARY
1979
A method of forming a structural stiffening rib on a curved resin/glass fibre shell using a plastics foam (eg polyethylene) is described.
H o s e - r e i n f o r c e d with discontinuous fibers oriented in the radial direction (Monsanto Co) Br Pat 1 514 620
(14 June 1978) An extrudable composite when forced through a channel of correct geometry enables the fibres to be radially oriented. These dimensions are described, Improvements in or relating to the manufacture of porous carbon bodies ( U K A E A ) Br Pat 1 514 171 (14
June 1978) A porous a) carbon or b) silicon
carbide network is produced by melt oppining petroleum pitch containing either a) 10% AI20a particles or b) 30-40% Si, allowing the fibres to partially stick together before oxidation and carbonisation. The application is porous electrical resistance heaters.
Improvements in or relating to fibre-reinforced composites ( N R D C ) Br Pat 1,514 239 (14 June
1978)
A glass fibre reinforced cement/cenospheres material is described. The cenospheres are a small proportion of pulverised fuel ash, but are used in the composite at a loading of at least 30%. A monomer impregnated version which can be heat cured is also described.
51