Stresses induced by thermal or chemical means are commonly used to toughen glass. This is known to result in large increases in the quasi-static strengths of the glass. Impact performance of such materials has, however, received less study. In this paper the performance of a thermally toughened & 2 chemically toughened glasses under liquid impact are studied. The results are compared to data obtained on annealed soda-lime glass The increase in damage threshold is not as great as the increase in quasi-static strength would suggest. Also, the behaviour of these materials under multiple impact is different from that seen in non-toughened materials. These features are discussed in terms of a crack extension model. A computer simulation based on interactions of Rayleigh waves & toughening stresses with an idealised flaw distribution supports the model.
