Determination of plastic properties of metals by instrumented indentation using a stochastic optimization algorithm

Peyrot, Isabelle Comby; Bouchard, Pierre‐Olivier; Ghisleni, R.; Michler, Johann

doi:10.1557/jmr.2009.0118

Cited by 14 publications

(4 citation statements)

References 45 publications

(59 reference statements)

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“…Index i relates to the number of individuals generated within a population. More details about this ES algorithm can be found in [46]. It has not been possible to match perfectly the experimental results with the classical Lemaitre damage potential for both grades.…”

Section: Application To Precompression-tensile Testsmentioning

confidence: 99%

An enhanced Lemaitre model formulation for materials processing damage computation

et al. 2010

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ABSTRACT:The Lemaitre damage model is now widely used to deal with coupled damage analyses for various mechanical applications. In this article, different extensions of the model are presented and discussed to deal with complex multiaxial configurations -such as multi-stages bulk forming processes. A specific treatment is done to account for compressive damage growth, and a stress triaxiality cut-off value is considered to avoid any damage evolution below a critical negative triaxiality. The damage potential is also modified to deal with highly ductile materials, and the plastic strain is split into a negative part and a positive part to differentiate damage growth for compressive states of stress and for tensile states of stress. Finally, an anisotropic damage approach based on the comparison between grain flow orientation and principal loading directions is defined. A combination of these extensions is achieved within a single Lemaitre formulation. Application on different examples show the robustness and accuracy of the model defined in this paper.

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Section: Application To Precompression-tensile Testsmentioning

confidence: 99%

An enhanced Lemaitre model formulation for materials processing damage computation

et al. 2010

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“…The underlying concept is thus clear and unencumbered by uncertainty about the validity of the procedure. However, for it to be a tool of widespread utility, concerns need to be addressed relating to the rate of convergence (in parameter space) on the "solution", [13,[42][43][44][45][46] the possibility that it is not "unique", the resolution requirements for the experimental outcome, etc.…”

Section: Pip Proceduresmentioning

confidence: 99%

A Critical Appraisal of the Instrumented Indentation Technique and Profilometry‐Based Inverse Finite Element Method Indentation Plastometry for Obtaining Stress–Strain Curves

Campbell¹,

Zhang

Burley³

et al. 2021

Adv Eng Mater

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A comparison is presented between conventional tensile stress‐strain curves and those obtained via two methodologies based on (spherical) indentation. The first, termed Instrumented Indentation Technique (IIT), involves conversion of load‐displacement data to stress‐strain curves via analytical expressions. This has been done using loads below 1 N (“nano”) and in the kN range (“macro”). The other procedure, termed profilometry‐based indentation plastometry (PIP), is based on repeated finite element method (FEM) simulation, using the residual indent profile as the target outcome and obtaining the best fit set of parameter values in a constitutive stress‐strain law. This has been done on a macro scale only. The data from nano‐IIT tend to be very noisy and variable, whereas those from macro‐IIT are more reproducible and less noisy. With one of the two empirical formulations employed, the agreement of the macro‐IIT with experiment is close to being acceptable for the work hardening characteristics, although inferred values of the yield stress are in poor agreement with those from tensile testing. In contrast to this, the PIP procedure provides outcomes that are in close agreement with those from tensile testing, concerning both yield stress and work hardening. The causes of this are explored and discussed.

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“…The underlying concept is thus clear and unencumbered by uncertainty about the validity of the procedure. However, for it to be a tool of widespread utility, concerns have to be addressed relating to the rate of convergence (in parameter space) on the "solution", [14][15][16][17][18][19] the possibility that it is not "unique", the resolution requirements for the experimental outcome, etc. It has already been applied using a commercially available integrated product to study industrial cases.…”

Section: Introduction 1obtaining Stress-strain Curves From Indentation Datamentioning

confidence: 99%

The Effect of Residual Stresses on Stress–Strain Curves Obtained via Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

Burley¹,

Campbell²,

Reiff-Musgrove

et al. 2021

Adv Eng Mater

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This paper concerns, the effect of (unknown) residual stresses in the near‐surface region of a sample on outcomes of an indentation plastometry technique for obtaining stress–strain relationships, using relatively large spherical indenters. The technique is based on the iterative finite element method (FEM) simulation of indentation, so as to infer the true stress–strain curve of the material (with the target outcome being the profile of the residual indent). It is expected that residual stress levels (if significant compared with the yield stress) are likely to influence the outcome, and indeed this forms the basis of many attempts to measure residual stresses in this way (using a known stress–strain curve). However, there are important issues of sensitivity here, which affect the reliability of such procedures and are also relevant to the accuracy of stress–strain curves inferred from measurements made on samples containing unknown levels of residual stress. Herein, both experimental work on samples with (equal‐biaxial) residual stresses created by the application of external loads and extensive FEM modeling to explore various scenarios are covered. The main conclusion is that the sensitivities involved are in general very low, particularly with relatively deep indentation. Inferred stress–strain curves are thus likely to be quite accurate, even in the presence of relatively high levels of residual stress. Conversely, the measurement of residual stress levels via this procedure is likely to be rather inaccurate, although the reliability is improved using shallow penetration (low ratio of depth‐to‐indenter radius). It is also noted that tensile residual stresses tend to influence outcomes more strongly than compressive ones.

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Determination of plastic properties of metals by instrumented indentation using a stochastic optimization algorithm

Cited by 14 publications

References 45 publications

An enhanced Lemaitre model formulation for materials processing damage computation

An enhanced Lemaitre model formulation for materials processing damage computation

A Critical Appraisal of the Instrumented Indentation Technique and Profilometry‐Based Inverse Finite Element Method Indentation Plastometry for Obtaining Stress–Strain Curves

The Effect of Residual Stresses on Stress–Strain Curves Obtained via Profilometry‐Based Inverse Finite Element Method Indentation Plastometry

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