Effect of load-dependence of hardness on indentation toughness determination for soda-lime glass

By analyzing the indentation data on soda-lime glass, it was found that, in the indentation toughness determination with the basic equation proposed by Anstis et al. [G.R. Anstis, P. Chantikul, B.R. Lawn, D.B. Marshall, J. Am. Ceram. Soc. 64 (1981) 533], treating the measured hardness as a constant would result in an indentation-load-dependent toughness number. A modified toughness equation was then proposed in which a load-independent hardness number was incorporated.