Cone indentation of time-dependent materials: The effects of the indentation strain rate

Mechanical modelling of indentation-induced densification in amorphous silica

“…The mesh is specially refined near the contact zone. Its spatial extent is large enough to make the results unsensitive to the location of the outer boundaries [39]. The size of the global mesh is one hundred times smaller than the contact radius.…”

“…When elastoplastic solids are indented by rigid self similar indenters, the principle of geometric similarity can be applied [17,39,41]. This principle [42] states that if two indentations are made by the same geometric shapes, then, whatever their size, the strain ε ij and stress σ ij distributions around the indentation will be geometrically similar.…”

Improvement in depth-sensing indentation to calculate the universal hardness on the entire loading curve

“…Using different material models from simple linear Maxwell (Feng and Ngan, 2002;Tang and Ngan, 2003) to a power-law creep model , the authors provide formula useful for calculating the true elastic stiffness and the elasto-plastic displacement in situations with significant indentation creep. Additional assemblage of elementary rheological models have been suggested by Kermouche et al (2006) whom associate several Maxwell models in series or in parallel. For linear viscoelastic solids and for power-law creep solids, the Maxwell model is extended to elastic-viscoplastic solids following a Bingham-Norton law (Lemaitre and Chaboche, 1994).…”

A new method to determine the true projected contact area using nanoindentation testing

“…A Berkovich diamond tip (tip defect height h 0 = 15 nm approximately, measured with the Loubet method on a fused silica sample [5]) and a diamond tip with β = 40 • (tip defect negligible) were used. For each sample, loading and unloading were performed at constant strain rate, with Ṗ /P = 0.03 s −1 [31], except for the PMMA sample, where Ṗ /P = 0.03 s −1 for Berkovich indentation and Ṗ /P = 0.07 s −1 for indentations with the sharpest tip [32]. For indentations with the sharpest tip, the CSM method was not used in order to avoid oscillation effects in the C calculation [33].…”