Evaluation of the effectiveness of representative methods for determining Young's modulus and hardness from instrumented indentation data

Abstract

The effectiveness of Oliver & Pharr's (O&P's) method, Cheng & Cheng's (C&C's) method, and a new method developed by our group for estimating Young's modulus and hardness based on instrumented indentation was evaluated for the case of yield stress to reduced Young's modulus ratio ( y /E r ) у 4.55 × 10 −4 and hardening coefficient (n) р 0.45. Dimensional theorem and finite element simulations were applied to produce reference results for this purpose. Both O&P's and C&C's methods overestimated the Young's modulus under some conditions, whereas the error can be controlled within ±16% if the formulation was modified with appropriate correction functions. Similar modification was not introduced to our method for determining Young's modulus, while the maximum error of results was around ±13%. The errors of hardness values obtained from all the three methods could be even larger and were irreducible with any correction scheme. It is therefore suggested that when hardness values of different materials are concerned, relative comparison of the data obtained from a single standard measurement technique would be more practically useful. It is noted that the ranges of error derived from the analysis could be different if different ranges of material parameters y /E r and n are considered.

Structural, mechanical properties and composition analysis of boron phosphide coatings

“…The physical thicknesses of the coatings were measured from section microstructure. The hardness and modulus of the coatings were measured by nano-indenter (nano-indenter Ò XP) [11]. The chemical composition and valence states of the coatings were studied in detail by XPS (ThermoScientific ESCALAB250, American) with a HSA analyser [12].…”

Biomechanics of the Bat Limb Skeleton: Scaling, Material Properties and Mechanics

“…We also propose that nanoindentation [Turner et al, 1999;Van Landingham, 2003;Radovic et al, 2004;Chen et al, 2006;Kim et al, 2006;Ma et al, 2006;Orso et al, 2006] is a promising technique for ascertaining mechanical properties of bone samples too small to test by conventional material testing, and for resolving variation in mechanical properties on a microscopic scale. This approach employs a microscopic indenter, typically 1-10 m in diameter, that can be applied to a prepared surface with a small, precisely measured force, in the range of tens to hundreds of millinewtons, to a controlled depth, typically hundreds to thousands of nanometers.…”

Revelation of a functional dependence of the sum of two uniaxial strengths/hardness on elastic work/total work of indentation

“…In our previous work, 15 it was demonstrated that for W e /W < 0.25, the Oliver & Pharr hardness may be very different from the real hardness (≡ indentation load/real projected contact area). In addition, the relationships established to correlate a true hardness with a representative yield are not applicable to the Oliver & Pharr hardness.…”