Evaluation of the fracture toughness of brittle hardening materials by Vickers indentation

• Hardening effects are incorporated in the fracture toughness evaluation.
• Equivalent non-hardening material model is proposed to reduce computational costs.
• Proposed model is verified with Vickers indentation on Si(1 0 0) and Ge(1 0 0).

We propose a Vickers indentation cracking-based method for evaluating the fracture toughness of brittle materials exhibiting strain hardening. The approach is an extension of the recent method by Hyun et al. (2015) for non-hardening materials to hardening materials. The hardening material is simplified by an equivalent non-hardening material with an elevated modified yield strain so that the fracture toughness of a hardening material can be evaluated with the formula proposed by Hyun et al. The proposed extension is verified by comparison with experimental results from nanoindentation tests on Ge(1 0 0) and Si(1 0 0).