SPALLATION OF POLYCARBONATE UNDER LASER-DRIVEN SHOCKS

Laser driven shocks have been used to investigate dynamic failure (spa llation) of polycarbonate under uniaxial tensile loading at very high strain rate, of the order of 10(7) s(-1). First, uninstrumented recove ry shots have been performed, post-test examination of the fracture da mage has been carried out, and the influences of the experimental para meters (loading conditions and target thickness) have been analyzed. T hen, an attempt to model the response of polycarbonate to plane shock loading has been made. On one hand, in-situ measurements have been per formed in polycarbonate samples submitted to the plane detonation wave of a strong explosive, and the results have led to content with simpl e constitutive relations. On the other hand, piezoelectric measurement s under laser shocks have provided a characterization of the loading p ressure pulse, and comparisons of the measured and computed signals ha ve confirmed the ability of the model to describe wave propagation in polycarbonate. Finally, the spallation experiments have been simulated . A spall strength has been estimated, on the basis of the experimenta l data, and the predictive capability of the model has been tested.