The linear softening cohesive zone model of Soutis et al [2, 6] successfully predicts the effects of an open hole and lay-up upon the compressive strength and microbuckle zone size at failure. In the analysis, the inelastic deformation associated with fibre microbuckling and matrix plasticity developed at the hole edges is mathematically replaced with a line-crack loaded across its faces by a bridging normal traction that decreases linearly with the overlap displacement of the microbuckle. The model takes as its input the laminate unnotched strength and the critical crack closing displacement, which is related to the in-plane compressive fracture toughness of the laminate. A value of 40 µm appears to give an excellent correlation between predicted and measured OHC data for all systems and lay-ups examined in [10]. The cohesive zone approach offers a technique for the prediction of OHC strength, which is simple and easy to apply and has the prospect of being used as a preliminary design tool for laminated polymer composite structures. ACKNOWLEDGEMENTS The author would like to thank his research students for assisting with the collection of experimental data and the Engineering and Physical Sciences Research Council and the British Ministry of Defence for financial support. REFERENCES 1. Soutis, C. (1991) Comp. Sci. & Techn., 42(4), 373-392. 2. Soutis, C., Fleck, N.A. and Smith, P.A. (1991) J Comp. Mat., 25, 1476-1498. 3. Soutis, C. (1997). In: Composite Materials: Testing & Design, Thirteenth volume, ASTM STP 1242, S.J. Hooper, Ed., American Society for Testing & Materials, 168-176. 4. Berbinau, P., Soutis, C.,Goutas, P. and Curtis, P.T. (1999) Composites A, 30(10), 1197-1207. 5. Budiansky, B. (1983) Computers & Structures, 16(1), 3-12. 6. Soutis, C., Curtis, P.T. and Fleck, N.A. (1993) Proc. R. Soc. London A, 440, 241-256. 7. Soutis, C. and Curtis, P.T. (2000) Composites: Part A, 31, 733-740. 8. Dugdale D.S. (1960) J. Mech. Phys. Solids, 8, 100-104. 9. Rice, J.R. (1968). In: Mathematical Analysis in the Mechanics of Fracture, 2, Academic Press, N.Y. 10. Smith, F.C. (2000) PhD Thesis, Imperial College, London, UK. 11. Soutis, C., Smith, F.C. and Matthews, F.L. (2000) Composites: Part A, 31, 531-536.
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