Paper number 745


S.W.G.Travis1, M.Bateson2, J.B. Doble1, R.E.Palmer1, V. Paloumbi3 and P.T.Curtis1

1Mechanical Sciences Sector, Defense Evaluation and Research Agency,
Farnborough. Hampshire. GU14 0LX, United Kingdom
2Mc Laren International Ltd, Woking Business Park, Albert Drive,
Woking. Surrey GU21 5GY, United Kingdom
3Mechanical Engineering Department, Imperial College of Science,
Technology and Medicine Exhibition Road, London SW7 2AZ

Summary Since carbon fibres were first produced in the 1960s, considerable advances have been made in improving their mechanical properties and those of their composites. Tensile strengths can now exceed 5GPa and , for different fibres, moduli in excess of 600GPa are achieved. These have not been accompanied by comparable improvements in compressive properties, because failure in composites is determined by buckling criteria. Large diameter hollow carbon fibre has the potential to achieve significant improvements in compressive strength; to improve damage tolerance and, possibly, serve as a "smart" material or in medical applications. MSS /DERA has developed a technique for spinning hollow PAN precursor fibres and converting them into useful carbon fibre. Although consistency in fibre structural morphology has been difficult to attain, the constituent carbon is found to be similar to that of high strength carbon fibre. Simple mechanical testing has, however, revealed that although comparable modulus can be realised, the Ultimate Tensile Strength (UTS) is lower. This is believed to be a consequence of flaws/inhomogeneities and the lack of structural homogeneity within filaments. Even with such experimental fibres, preliminary compression testing indicates higher strain to first failure in comparison with a commercial fibre.
Keywords carbon fibre, compression, processing, hollow.

Theme : Fibres ; Glass and Carbon Fibres

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