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From time to time there continue spectacular failures during the early service life of very high performance fibre composites. No comprehensive treatment of the toughness of fibre composites particularly under impact conditions is known to the authors. It seems worthwhile to recall the early experiments and ideas developed between 1965 and 1973 or so concerned with the physical principles of debonding, pull-out, transverse and longitudinal splitting, matrix plasticity, multiple cracking and interfacial shear all of which contribute to the toughness.
Work associated with the names of Gordon, Cooper, Outwater, Tyson, Prewo, McGarry, Ewins, Potter, Bradshaw,Sidey and their colleagues as well as those of the authors and others will be recalled and commented upon. Finally some remarks will be made on the need for a diagnostic parameter for cumulative damage and fatigue of fibre composites and a suggestion made that this be measurement of Poissons ratio.