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Fracture

We have, over the years, studied crack growth in a wide range of materials including glasses, polymers, single crystals, metals and composites. A variety of techniques have been used or developed to follow rapid crack growth (high-speed photography, ultra-sonics, electrical). We have also worked on crack initiation and so-called 'stable' crack growth, obtaining fracture data which can be used to design components and predict their life-times in practical situations. As physicists, our approach has been essentially trying to understand the basic processes affecting crack initiation and propagation. Sophisticated optical techniques have recently been developed in our laboratory for studying crack tip conditions and material deformation.

We have made contributions to a variety of practical uses of fracture. For example, we:

      • Developed a model to explain fragmentation in rock-blasting;
      • Developed a new way of interrupting electric current based on a 'fracture-switch';
      • Suggested improvements to the diamond cleaving process
      • Studied the crack patterns which determine the erosion or wear of brittle materials.
High speed photographic sequence of the impact of a 2mm diameter tungsten carbide ball onto toughened glass at 150 m/s. Interface time 1 µs. M.M. Chaundri, L. Chen, Nature 329 (1986) 48-50. Dynamic failure of a 5mm diameter polycarbonate disc deformed in dropweight apparatus. S.M. Walley, J.E. Field, P.H. Pope, N.A. Safford Phil. Trans. R. Soc. Lond. A328 (1989) 1-33