Numerical construction of axisymmetric slip-line fields for indentation of thick blocks by rigid conical indenters and friction at the tool-metal interface

Dual-indentation technique for the assessment of strength properties of cohesive-frictional materials

“…In this case, the proposed method can be used to determine initial values of the cohesion and friction angle for the iterative backanalysis. A similar remark can be made for contact friction (which has been investigated for cohesive materials by Chitkara and Butt, 1992) and strain hardening effects, which we ignore in our yield design solutions. These effects appear to be negligible in the case of our ÔmodelÕ material, since the diamond-metal contact friction is relativy low, and since metallic glass shows almost no strain hardening.…”

“…A similar minimum phenomenon was reported by Houlsby and Wroth (1982) for the cone penetration test used in geotechnical applications, who reported a minimum of h ' 50°from exploring a lower bound approach. Such a minimum phenomenon has been also found for frictionless materials around h ' 20° (Chitkara and Butt, 1992), and the presence of friction appears to shift the minimum to higher cone angles. This minimum phenomenon is an important property regarding uniqueness of the inverse problem of the assessment of the cohesion and friction angle by two indentation tests.…”

“…From slip-line field solution for indentation in a rigid-plastic solids by a frictionless rigid wedge, Tabor (1948) suggested a hardness vs. yield stress relationship of the form H/Y = 3. This Ôrule of thumbÕ (Schuh and Nieh, 2004) got under scrutiny by several researchers for conical indentation into rigid plastic solids with and without contact friction (Locket, 1963;Chitkara and Butt, 1992), elastic-perfectly plastic solids (see discussion in Johnson, 1985) and more recently for work-hardening materials (Cheng and Cheng, 2004). All these studies lead to the conclusion that hardness is not a material property, but rather a snapshot of materials mechanical properties and indenter geometry dependent.…”

Hardness–packing density scaling relations for cohesive-frictional porous materials

“…0 comes close to the rigid-plastic assumption of yield design approaches which can be found early on in the indentation literature. For instance, Locket (1963) and Chitkara and Butt (1992) developed yield design solutions for conical indentations in cohesive rigid-plastic solids (without and with friction at the indenter-material interface). More recently, using the upper bound theorem of yield design, Ganneau et al (2006) developed a dual indentation approach which allows the determination of cohesion and friction of a Mohr-Coulomb solid from the dependence of the hardness-to-cohesion ratio on the cone angle:…”

Mechanical analysis of indentation experiments with a conical indenter

“…A complete description of the axisymmetric indentation of elastic solids (Young's modulus, E, Poisson ratio, ) is available [3]: for a conical indenter c ¼ 2/ and H Ã ¼ X/2 (see below). The conical indentation of rigid perfectly plastic (RPP) solids has been analyzed mainly by the slip line field (SLF) method [4]. For elastic perfectly plastic (EPP) solids Johnson [5] provides the matter balance in the model of the expansion of a spherical cavity proposed by Hill and so estimates H* versus the indentation index X:…”