The duality in mechanical property extractions from Vickers and Berkovich instrumented indentation experiments

Casals, O.; Alcalá, Jorge

doi:10.1016/j.actamat.2005.03.051

Cited by 97 publications

(97 citation statements)

References 35 publications

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“…13,14,24,25 It is worth mentioning that although the P-h curves are similar, significant differences on all indentation parameters are expected between the conical and pyramidal cases. 16,26 The material tested was represented by a 2D mesh using 37,282 four-noded, axisymmetric type CAX4R elements. The mesh close to the contact was refined to improve the accuracy and convergence of the analysis, and the mesh became gradually coarser when moving away from the initial contact region.…”

Section: Finite Element Analysismentioning

confidence: 99%

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Analysis of the tip roundness effects on the micro- and macroindentation response of elastic–plastic materials

2009

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In this work, the effects of indenter tip roundness on the load-depth indentation curves were analyzed using finite element modeling. The tip roundness level was studied based on the ratio between tip radius and maximum penetration depth (R/h max ), which varied from 0.02 to 1. The proportional curvature constant (C), the exponent of depth during loading (a), the initial unloading slope (S), the correction factor (b), the level of piling-up or sinking-in (h c /h max ), and the ratio h max /h f are shown to be strongly influenced by the ratio R/h max . The hardness (H) was found to be independent of R/h max in the range studied. The Oliver and Pharr method was successful in following the variation of h c /h max with the ratio R/h max through the variation of S with the ratio R/h max . However, this work confirmed the differences between the hardness values calculated using the Oliver-Pharr method and those obtained directly from finite element calculations; differences which derive from the error in area calculation that occurs when given combinations of indented material properties are present. The ratio of plastic work to total work (W p /W t ) was found to be independent of the ratio R/h max , which demonstrates that the methods for the calculation of mechanical properties based on the indentation energy are potentially not susceptible to errors caused by tip roundness.

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Section: Finite Element Analysismentioning

confidence: 99%

“…[13][14][15][16] One possible way to study the effect of indenter tip roundness is based on the ratio R/h max . In the case of conical indenters with semiangle equal to 70.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the tip roundness effects on the micro- and macroindentation response of elastic–plastic materials

2009

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“…This indicates that the initial unloading slope (S) is the test variable most susceptible to experimental errors. Additionally, when comparing the values obtained for the confidence interval of dimensionless function P 4 with those calculated from the data in the literature, 8,42 it is possible to note that a decrease in the maximum load results in an increase in the confidence interval, which is not observed for the confidence interval of the dimensionless function P 1 .…”

Section: Methodsmentioning

confidence: 95%

Analysis of the effects of conical indentation variables on the indentation response of elastic–plastic materials through factorial design of experiment

2009

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In this work, the effects of conical indentation variables on the load-depth indentation curves were analyzed using finite element modeling and dimensional analysis. A factorial design 2 6 was used with the aim of quantifying the effects of the mechanical properties of the indented material and of the indenter geometry. Analysis was based on the input variables Y/E, R/h max , n, y, E, and h max . The dimensional variables E and h max were used such that each value of dimensionless Y/E was obtained with two different values of E and each value of dimensionless R/h max was obtained with two different h max values. A set of dimensionless functions was defined to analyze the effect of the input variables:, P 2 = h c /h, P 3 = H/Y, P 4 = S/Eh max , P 6 = h max /h f , and P 7 = W p /W T . These six functions were found to depend only on the dimensionless variables studied (Y/E, R/ h max , n, y). Another dimensionless function, P 5 = b, was not well defined for most of the dimensionless variables and the only variable that provided a significant effect on b was y. However, b showed a strong dependence on the fraction of the data selected to fit the unloading curve, which means that b is especially susceptible to the error in the calculation of the initial unloading slope.

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“…Compared to Berkovich indentation, the situation is more complex for spherical indentation as the amount of pile-up is a function of the indentation depth [5]. Some methodologies, alternative to that of Oliver and Pharr, attempt to account for the lack of knowledge of the true contact area in instrumented indentation [6][7][8], in particular for metals. In these approaches, however, the problem is that a single indentation load-displacement curve can have multiple solutions for the mechanical properties, except for special cases.…”

Section: A P = a 2 = (2r-h C )H Cmentioning

confidence: 99%

Quantitative assessment and prediction of contact area development during spherical tip indentation of glassy polymers

Pelletier¹,

Toonder²,

Govaert³

et al. 2008

Philosophical Magazine

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The duality in mechanical property extractions from Vickers and Berkovich instrumented indentation experiments

Cited by 97 publications

References 35 publications

Analysis of the tip roundness effects on the micro- and macroindentation response of elastic–plastic materials

Analysis of the tip roundness effects on the micro- and macroindentation response of elastic–plastic materials

Analysis of the effects of conical indentation variables on the indentation response of elastic–plastic materials through factorial design of experiment

Quantitative assessment and prediction of contact area development during spherical tip indentation of glassy polymers

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