The dynamic mechanical behaviour of a carbon fibre composite using the split Hopkinson pressure bar

The thesis describes a series of experiments using a split Hopkinson pressure bar to study the mechanical behaviour of a carbon fibre composite at high rates of loading. The split Hopkinson pressure bar technique uses specimens in the form of a cylinder, sandwiched between two steel bars of the same diameter,as the specimen. Ona of the steel bars is subjected to an impact produced by a projectile from a gas gun specifically developed for this purpose. This produces a stress pulse incident on the specimen which will produce stresses within the specimen of up to 3 x 108 N/m2 with rise times of approximately 15 to 30 micro seconds. The study of material behaviour at these strain rates involves the study of stress wave propagation. The thesis initially discusses the theory of stress wave propagation and then gives a brief history of the Hopkinson pressure bar. The configuration used for this particular series of experiments is described and an account is given of its use to compare two different techniques of monitoring specimen behaviour. These were an optical and a strain gauge method. (...continues)