Fracture mechanisms induced in a brittle material by a hard cutting indenter

The process of indentation of brittle and quasi-brittle materials has been extensively investigated both from the experimental and the theoretical poi nt of view. Also, the elastic stress fields induced by sliding bodies are w ell known and have been used to predict fracture patterns below moving cont acts. Quite surprisingly, only a few studies have tried to explain the mech anics of cutting due to an indenter which penetrates inside the material. I n this paper, an attempt is made to find some general relations for the cut ting process in quasi-brittle materials, under different hypotheses for the microscopic failure behaviour, namely a simple frictional mechanism, plast ic crushing and linear elastic fracture mechanics. These mechanisms interac t with each other, and provide a particular load-penetration law and a pecu liar cutting advancement. Some numerical simulations by the lattice model h ave been also carried out, in order to verify the assumptions. Dimensional analysis permits to highlight remarkable size-scale effects on the cutting strength and provides some hints for enhancing the performances of cutting tools. (C) 2001 Elsevier Science Ltd. All rights reserved.