Refinement and application of a modified indentation toughness technique

The modified indentation toughness technique, in which indentation strength and crack length at instability are combined in toughness determination, is re-assessed by addition of new data and materials, including those of other investigators. A materials ranking scheme is introduced and the technique extended in determination of the variation in toughness with crack length for T curve materials. In all, 20 materials are assessed here to refine the precision and accuracy of the technique and enable toughness estimation for ceramics at strength relevant length scales. Artifacts associated with conventional indentation toughness methods are largely removed by the modified technique.