Critical Evaluation of Spherical Indentation Stress-Strain Protocols for the Estimation of the Yield Strengths of Steels

Mohan, Soumya; Millan-Espitia, Natalia; Yao, Mengdi; Steenberge, N. Van; Kalidindi, Surya R.

doi:10.1007/s11340-021-00689-7

Cited by 13 publications

(5 citation statements)

References 66 publications

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“…The first, commonly termed the "Instrumented Indentation Technique" (IIT), involves converting load-displacement data directly to stress-strain curves, using analytical relationships. This approach has been very popular, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] and is attractive in terms of quickly and easily obtaining the final outcome, but it involves gross simplifications concerning the actual stress and strain fields under an indenter. A slight variant of the concept involves the use of neural network procedures [15][16][17] to relate loaddisplacement data to corresponding stress-strain curves-i.e., to "train" the analytical relationship, although in practice this is subject to similar limitations.…”

Section: Doi: 101002/adem202100437mentioning

confidence: 99%

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Clyne

Campbell²,

Burley³

et al. 2021

Adv Eng Mater

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This is a review of the current state‐of‐the‐art regarding a particular approach to extraction of the (quasistatic) stress–strain relationship of a metallic sample from an indentation experiment. It is based on the application of a relatively high load (kN range) to the sample via a large spherical indenter (≈1 mm radius), followed by measurement of the indent profile. This profile is then used as the target outcome for inverse finite element method (FEM) modeling of the test, aimed at converging on the best fit set of parameter values in a constitutive plasticity law (true stress–true strain relationship). This can then be used to simulate any specified loading configuration, including a conventional tensile test. Commercial products are now available in which the indentation, profilometry, and convergence operations are all automated and completed within a few minutes. The review covers the various conceptual and practical issues involved in implementation and optimization of these procedures, including both those related to the measurement system (experimental and FEM simulation) and those associated with the sample (such as anisotropy, inhomogeneities, and residual stresses). An attempt is made to convey an impression of the expected levels of reliability and also the scope for obtaining insights that are not readily obtainable using other types of test.

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Section: Doi: 101002/adem202100437mentioning

confidence: 99%

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Clyne

Campbell²,

Burley³

et al. 2021

Adv Eng Mater

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“…Prior work has recommended that the contact radius should be less than 1/15th of the sample thickness. 25 As a result, the indentations in this study were restricted to fairly low indentation depths. Further, it is clear that the three samples tested have distinct yield strengths, with A40 showing the highest yield strength value (Table 1).…”

Section: Resultsmentioning

confidence: 99%

An approach towards plastic scintillators from thermally activated delayed fluorescent dyes and cross-linkable bismuth compounds

et al. 2022

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“…In the determination of plastic response of metals, a uniaxial tensile test is the widely accepted standard, despite the convenience of indentation testing (Salzbrenner et al, 2017;Clyne et al, 2021;Mohan et al, 2021). The tensile test produces repeatable results and is often insensitive to small spatial fluctuations in yield strength, relative to the specimen cross-sectional area (Nichols, 1980).…”

Section: Discussionmentioning

confidence: 99%

Uncertainty Quantification of a High-Throughput Profilometry-Based Indentation Plasticity Test of Al 7075 T6 Alloy

et al. 2022

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The quantification of spatially variable mechanical response in structural materials remains a challenge. Additive manufacturing methods result in increased spatial property variations—the effect of which on component performance is of key interest. To assist iterative design of additively manufactured prototypes, lower-cost benchtop test methods with high precision and accuracy will be necessary. Profilometry-based indentation plastometry (PIP) promises to improve upon the instrumented indentation test in terms of the measurement uncertainty. PIP uses an isotropic Voce hardening model and inverse numerical methods to identify plasticity parameters. The determination of the baseline uncertainty of PIP test is fundamental to its use in characterizing spatial material property variability in advanced manufacturing. To quantify the uncertainty of the PIP test, ninety-nine PIP tests are performed on prepared portions of a traditionally manufactured Al 7075 plate sample. The profilometry data and the Voce parameter predictions are examined to distinguish contributions of noise, individual measurement uncertainty, and additional set-wide variations. Individual measurement uncertainty is estimated using paired profilometry measurements that are taken from each indentation. Principal component analysis is used to analyze and model the measurement uncertainty. The fitting procedure used within the testing device software is employed to examine the effect of profile variations on plasticity predictions. The expected value of the error in the plasticity parameters is given as a function of the number of tests taken, to support rigorous use of the PIP method. The modeling of variability in the presence of measurement uncertainty is discussed.

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Critical Evaluation of Spherical Indentation Stress-Strain Protocols for the Estimation of the Yield Strengths of Steels

Cited by 13 publications

References 66 publications

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

An approach towards plastic scintillators from thermally activated delayed fluorescent dyes and cross-linkable bismuth compounds

Uncertainty Quantification of a High-Throughput Profilometry-Based Indentation Plasticity Test of Al 7075 T6 Alloy

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