Journal of Materials Science

, Volume 14, Issue 8, pp 1982–1996 | Cite as

Fracture toughness and crack-growth measurements in GRP

  • M. J. Owen
  • R. J. Cann


Critical crack tip stress intensity factor (Kc) measurements were made for polyester resin reinforced with glass chopped strand mat (CSM) and woven roving fabric (WRF). Specimen thickness and initial crack length were varied for centre notched (CN) 100 mm wide▴ specimens. Some specimens were saturated by immersion in water under pressure. Kc was negligibly affected by specimen thickness and it was concluded that plane strain conditions are not achieved in laminates of normal thickness. Scatter can be reduced by adjusting results to a standard glass content and Kc varies continuously with crack length. The CSM experiments were extended to 915 mm wide specimens which failed at very low nett section stresses but there may be a region in which Kc is roughly constant relative to crack length. In WRF specimens, however, it is the nett section stress which is constant at a value substantially below the UTS. Fatigue crack-growth studies were carried out on CN specimens. The Paris law adequately describes crack growth in CSM specimens at low rates of growth but Forman's law is better at high rates of growth. Neither law is valid for WRF material when dry but the behaviour changes after saturation with water. The crack-growth resistance of both materials is severely reduced by saturation with water.


Fracture Toughness Stress Intensity Factor Crack Length Specimen Thickness Polyester Resin 
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Copyright information

© Chapman and Hall Ltd. 1979

Authors and Affiliations

  • M. J. Owen
    • 1
  • R. J. Cann
    • 1
  1. 1.Department of Mechanical EngineeringUniversity of NottinghamNottinghamUK

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