Experimental simulation of brittle failure initiation by indentation test for cutting tool materials.

Crack initiation in brittle materials

In this paper we study the crack initiation in a hyper-elastic body governed by a Griffith’s type energy. We prove that, during a load process through a time dependent boundary datum of the type t → tg(x) and in absence of strong singularities (this is the case of homogeneous isotropic materials) the crack initiation is brutal, i.e., a big crack appears after a positive time ti > 0. On the cont...

Failure of brittle layers on polymeric substrates from Vickers indentation

A study is made of median crack evolution in brittle coatings subjected to sharp contacts. A model bilayer system consisting of a glass plate bonded to a polycarbonate base, with a Vickers pyramid as indenter, is used to demonstrate the evolution in situ. The cracks undergo a phase of stable downward growth with increasing load. Beyond the coating mid-plane, flexural stresses (coupled with the ...

A Failure Analysis of an Experimental AlMgB14 Cutting Tool

A recently developed ultra-hard boride-based material, AlMgB14, has been fabricated into a standard cutting tool geometry (TPG-222) and tested using single-point turning of Ti-6Al-4V. The initial testing was conducted to compare this new cutting tool’s performance relative to a WC-Co cutting tool. During the tests the boride-based inserts suffered catastrophic failure for a wide range of cuttin...

Multiscale failure modelling of quasi - brittle materials

Cutting-Tool Materials and Cutting Fluids

The reasons for the availability of a large variety of cutting-tool materials is best appreciated by reviewing the top eight parameters in the first column in Table 22.2 on p. 638. Among various factors, the type of workpiece material machined, the type of operation, and the surface finish and dimensional accuracy required all affect the choice of a cutting-tool material. For example, for inter...