WAVE STEADINESS IN ALUMINAS

Plate impact experiments have been carried out on two aluminas of differing grain size using the Cambridge 50 mm gas gun. Tiles were constructed in thicknesses of 4, 8 and 12 mm and were impacted by 3 mm thick copper projectiles fired at 550 m s(-1). The longitudinal stress in the tiles was recorded using manganin stress gauges and a 1 GS s(-1) storage oscilloscope. Measurements were made of the elastic precursor of the deformation wave in each of these experiments. It was found that the elastic precursor varied significantly with thickness and that different behaviours were shown by the large and small grain size materials.