Hardened steel spherical particles 800 and 1000 um in diameter were firedonto blocks of soda lime and borosilicate (Pyrex) glasses at veloqtics up to 300 ms -l. The formation of the damage was photographed at a framing rate of 10's-± with a Beckman and Whitley rotating mirror framing camera to which a microscope was attached. The behaviour of the two glasses was very different; in pyrex glass distinct Hertzian cone cracks were formed, whereas in soda lime such cracks did not appear, but instead finger shaped splinter cracks were formed. Most of the damage occurred within 4-5 us of the impact and it was possible to resolve different modes of cracking during the loading and unloading parts of the impact. Qualitative quasistatic indentation analysis was found to explain the observations in the dynamic case reasonably well.
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