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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Fri, 19 Jul 2019 08:04:37 GMT2019-07-19T08:04:37ZQuantitative approach to determine the mechanical properties by nanoindentation test: Application on sandblasted materials
http://hdl.handle.net/10985/9675
Quantitative approach to determine the mechanical properties by nanoindentation test: Application on sandblasted materials
XIA, Yang; BIGERELLE, Maxence; BOUVIER, Salima; IOST, Alain; MAZERAN, Pierre-Emmanuel
A novel method is developed to improve the accuracy in determining the mechanical properties from nanoindentation curves. The key point of this method is the simultaneous statistical treatment of several loading curves to correct the zero point error and identify the material properties considering size effects. The method is applied to four sandblasted aluminum-based specimens with different surface roughness. A linear relationship is obtained between the standard deviation of the initial contact error and the roughness which highlights the effect of the surface roughness on the reproducibility of the indentation curves. Moreover, the smaller standard deviation of the hardness given by the method confirms the importance of considering the initial contact error for an accurate determination of the material properties.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/96752015-01-01T00:00:00ZXIA, YangBIGERELLE, MaxenceBOUVIER, SalimaIOST, AlainMAZERAN, Pierre-EmmanuelA novel method is developed to improve the accuracy in determining the mechanical properties from nanoindentation curves. The key point of this method is the simultaneous statistical treatment of several loading curves to correct the zero point error and identify the material properties considering size effects. The method is applied to four sandblasted aluminum-based specimens with different surface roughness. A linear relationship is obtained between the standard deviation of the initial contact error and the roughness which highlights the effect of the surface roughness on the reproducibility of the indentation curves. Moreover, the smaller standard deviation of the hardness given by the method confirms the importance of considering the initial contact error for an accurate determination of the material properties.Numerical simulation of sheet metal forming using anisotropic strain-rate potentials
http://hdl.handle.net/10985/9907
Numerical simulation of sheet metal forming using anisotropic strain-rate potentials
RABAHALLAH, Meziane; BOUVIER, Salima; BALAN, Tudor; BACROIX, Brigitte
For numerical simulation of sheet metal forming, more and more advanced phenomenological functions are used to model the anisotropic yielding. The latter can be described by an adjustment of the coefficients of the yield function or the strain rate potential to the polycrystalline yield surface determined using crystal plasticity and X-ray measurements. Several strain rate potentials were examined by the present authors and compared in order to analyse their ability to model the anisotropic behaviour of materials using the methods described above to determine the material parameters. Following that, a specific elastic-plastic time integration scheme was developed and the strain rate potentials were implemented in the FE code. Comparison of the previously investigated potentials is continued in this paper in terms of numerical predictions of cup drawing, for different bcc and fcc materials. The identification procedure is shown to have an important impact on the accuracy of the FE predictions.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10985/99072009-01-01T00:00:00ZRABAHALLAH, MezianeBOUVIER, SalimaBALAN, TudorBACROIX, BrigitteFor numerical simulation of sheet metal forming, more and more advanced phenomenological functions are used to model the anisotropic yielding. The latter can be described by an adjustment of the coefficients of the yield function or the strain rate potential to the polycrystalline yield surface determined using crystal plasticity and X-ray measurements. Several strain rate potentials were examined by the present authors and compared in order to analyse their ability to model the anisotropic behaviour of materials using the methods described above to determine the material parameters. Following that, a specific elastic-plastic time integration scheme was developed and the strain rate potentials were implemented in the FE code. Comparison of the previously investigated potentials is continued in this paper in terms of numerical predictions of cup drawing, for different bcc and fcc materials. The identification procedure is shown to have an important impact on the accuracy of the FE predictions.Application of a dislocation based model for Interstitial Free (IF) steels to Marciniak Stretch test simulations
http://hdl.handle.net/10985/10457
Application of a dislocation based model for Interstitial Free (IF) steels to Marciniak Stretch test simulations
CARVALHO RESENDE, Tales; SAADAOUI, Ayoub; BALAN, Tudor; ABED-MERAIM, Farid; BOUVIER, Salima; SABLIN, Simon-Serge
With a view to environmental, economic and safety concerns, car manufacturers need to design lighter and safer vehicles in ever-shorter development times. In recent years, High Strength Steels (HSS) like Interstitial Free (IF) steels, which have ratio of yield strength to elastic modulus, are increasingly used for sheet metal parts in automotive industry to reduce mass. The Finite Element Method (FEM) is quite successful to simulate metal forming processes but accuracy depends both on the constitutive laws used and their material parameters identification. Common phenomenological models roughly consist in the fitting of functions on experimental results and do not provide any predictive character for different metals from the same grade. Therefore, the use of accurate plasticity models based on physics would increase predictive capability, reduce parameter identification cost and allow for robust and time-effective finite element simulations. For this purpose, a 3D physically-based model at large strain with dislocation density evolution approach was presented in IDDRG2009 by the authors. This approach can be decomposed as a combination of isotropic and kinematic contributions. The model enables the description of work-hardening’s behaviour for different simple loading paths (i.e. uniaxial tensile, simple shear and Bauschinger tests) taking into account several data from microstructure (i.e. grain size, texture, etc.…). The originality of this model consists in the introduction of microstructure data in a classical phenomenological model in order to achieve work-hardening’s predictive character for different metals from the same grade. Indeed, thanks to a microstructure parameter set for IF steels, it is possible to describe work-hardening’s behaviour for different steels of grain sizes varying in the 8.5-22µm value range by only changing the mean grain size and initial yield stress values. Forming Limit Diagrams (FLDs) have been empirically constructed to describe the strain states at which a highly localized zone of thinning, or necking, becomes visible on the surface of sheet metals. FLDs can be experimentally obtained through Marciniak Stretch test, which is a modified dome test. It was designed to overcome the severe strain gradients developed by the traditional dome tests using a hemispherical punch (e.g. Nakajima test). Many automotive manufacturers use Marciniak Stretch test as a validation tool before simulating real parts. The work described is an implementation of a 3D dislocation based model in ABAQUS/Explicit together with its validation on a finite element (FE) Marciniak Stretch test. In order to assess the performance and relevance of the 3D dislocation based model in the simulation of industrial forming applications, FLDs will be plotted and compared to experimental results for different IF steels.
Fri, 01 Jan 2010 00:00:00 GMThttp://hdl.handle.net/10985/104572010-01-01T00:00:00ZCARVALHO RESENDE, TalesSAADAOUI, AyoubBALAN, TudorABED-MERAIM, FaridBOUVIER, SalimaSABLIN, Simon-SergeWith a view to environmental, economic and safety concerns, car manufacturers need to design lighter and safer vehicles in ever-shorter development times. In recent years, High Strength Steels (HSS) like Interstitial Free (IF) steels, which have ratio of yield strength to elastic modulus, are increasingly used for sheet metal parts in automotive industry to reduce mass. The Finite Element Method (FEM) is quite successful to simulate metal forming processes but accuracy depends both on the constitutive laws used and their material parameters identification. Common phenomenological models roughly consist in the fitting of functions on experimental results and do not provide any predictive character for different metals from the same grade. Therefore, the use of accurate plasticity models based on physics would increase predictive capability, reduce parameter identification cost and allow for robust and time-effective finite element simulations. For this purpose, a 3D physically-based model at large strain with dislocation density evolution approach was presented in IDDRG2009 by the authors. This approach can be decomposed as a combination of isotropic and kinematic contributions. The model enables the description of work-hardening’s behaviour for different simple loading paths (i.e. uniaxial tensile, simple shear and Bauschinger tests) taking into account several data from microstructure (i.e. grain size, texture, etc.…). The originality of this model consists in the introduction of microstructure data in a classical phenomenological model in order to achieve work-hardening’s predictive character for different metals from the same grade. Indeed, thanks to a microstructure parameter set for IF steels, it is possible to describe work-hardening’s behaviour for different steels of grain sizes varying in the 8.5-22µm value range by only changing the mean grain size and initial yield stress values. Forming Limit Diagrams (FLDs) have been empirically constructed to describe the strain states at which a highly localized zone of thinning, or necking, becomes visible on the surface of sheet metals. FLDs can be experimentally obtained through Marciniak Stretch test, which is a modified dome test. It was designed to overcome the severe strain gradients developed by the traditional dome tests using a hemispherical punch (e.g. Nakajima test). Many automotive manufacturers use Marciniak Stretch test as a validation tool before simulating real parts. The work described is an implementation of a 3D dislocation based model in ABAQUS/Explicit together with its validation on a finite element (FE) Marciniak Stretch test. In order to assess the performance and relevance of the 3D dislocation based model in the simulation of industrial forming applications, FLDs will be plotted and compared to experimental results for different IF steels.Modelling the effect of microstructure evolution on the macroscopic behavior of single phase and dual phase steels: Application to sheet forming process
http://hdl.handle.net/10985/13996
Modelling the effect of microstructure evolution on the macroscopic behavior of single phase and dual phase steels: Application to sheet forming process
BOUVIER, Salima; CARVALHO RESENDE, Tales; BALAN, Tudor; ABED-MERAIM, Farid
The aim of this work is to develop a dislocation density based model for IF and DP steels that incorporates details of the microstructure evolution at the grain-size scale. The model takes into account (i) the contribution of the chemical composition for the prediction of the initial yield stress, (ii) the description of initial texture anisotropy by incorporating grain-size dependent anisotropy coefficients in Hill’48 yield criterion, (iii) the contribution of three dislocation density “families” that are associated with forward, reverse and latent structures. It reproduces the macroscopic transient behaviors observed when strain-path changes occur. The model is implemented in FE code in order to assess its predictive capabilities in case of industrial applications.
Thu, 01 Jan 2015 00:00:00 GMThttp://hdl.handle.net/10985/139962015-01-01T00:00:00ZBOUVIER, SalimaCARVALHO RESENDE, TalesBALAN, TudorABED-MERAIM, FaridThe aim of this work is to develop a dislocation density based model for IF and DP steels that incorporates details of the microstructure evolution at the grain-size scale. The model takes into account (i) the contribution of the chemical composition for the prediction of the initial yield stress, (ii) the description of initial texture anisotropy by incorporating grain-size dependent anisotropy coefficients in Hill’48 yield criterion, (iii) the contribution of three dislocation density “families” that are associated with forward, reverse and latent structures. It reproduces the macroscopic transient behaviors observed when strain-path changes occur. The model is implemented in FE code in order to assess its predictive capabilities in case of industrial applications.Multi-scale investigation of highly anisotropic zinc alloys using crystal plasticity and inverse analysis
http://hdl.handle.net/10985/13176
Multi-scale investigation of highly anisotropic zinc alloys using crystal plasticity and inverse analysis
CAUVIN, Ludovic; RAGHAVAN, Balaji; BOUVIER, Salima; WANG, Xiaodong; MERAGHNI, Fodil
Zinc and its alloys are important industrial materials due to their high corrosion resistance, low cost and good ductility. However, the characterization of these materials remains a difficult task due to their highly anisotropic behavior, the latter being due to the influence of microstructural effects, i.e. loading orientation-dependent activation of different families of slip systems and subsequent texture evolution, rendering the development of a reliable material model considerably difficult. A micro-mechanical approach based on polycrystal plasticity would better describe the physical mechanisms underlying the macroscopic behavior. This improved model should ostensibly improve the comprehension of the mechanical behavior, compared to the macroscopic approach using solely phenomenological anisotropy models along with a prohibitively large number of experiments required to identify the material parameters. In this paper, a multi-scale Visco-Plastic Self-Consistent (VPSC) approach is used. It is based on a micro-scale model calibrated by microstructural and deformation mechanism information based on Electron Back-Scattered Diffraction (EBSD) to describe the macroscopic anisotropic mechanical response during sheet metal deformation. The critical resolved shear stress (CRSS) as well as the micro-scale crystal parameters are obtained by an inverse analysis comparing the simulated and experimental results in terms of obtained tensile curves along three different directions. In order to obtain a global solution for the identification, we then use the Covariance Matrix Adaptation-Evolution Strategy (CMA-ES) genetic algorithm to the inverse problem. We validate our approach by comparing the simulated and experimental textures and activated slip systems. Finally, the identified mechanical parameters are used to investigate the anisotropy of the alloy and predict its formability by determining the corresponding R-values and Hill yield coefficients.
Mon, 01 Jan 2018 00:00:00 GMThttp://hdl.handle.net/10985/131762018-01-01T00:00:00ZCAUVIN, LudovicRAGHAVAN, BalajiBOUVIER, SalimaWANG, XiaodongMERAGHNI, FodilZinc and its alloys are important industrial materials due to their high corrosion resistance, low cost and good ductility. However, the characterization of these materials remains a difficult task due to their highly anisotropic behavior, the latter being due to the influence of microstructural effects, i.e. loading orientation-dependent activation of different families of slip systems and subsequent texture evolution, rendering the development of a reliable material model considerably difficult. A micro-mechanical approach based on polycrystal plasticity would better describe the physical mechanisms underlying the macroscopic behavior. This improved model should ostensibly improve the comprehension of the mechanical behavior, compared to the macroscopic approach using solely phenomenological anisotropy models along with a prohibitively large number of experiments required to identify the material parameters. In this paper, a multi-scale Visco-Plastic Self-Consistent (VPSC) approach is used. It is based on a micro-scale model calibrated by microstructural and deformation mechanism information based on Electron Back-Scattered Diffraction (EBSD) to describe the macroscopic anisotropic mechanical response during sheet metal deformation. The critical resolved shear stress (CRSS) as well as the micro-scale crystal parameters are obtained by an inverse analysis comparing the simulated and experimental results in terms of obtained tensile curves along three different directions. In order to obtain a global solution for the identification, we then use the Covariance Matrix Adaptation-Evolution Strategy (CMA-ES) genetic algorithm to the inverse problem. We validate our approach by comparing the simulated and experimental textures and activated slip systems. Finally, the identified mechanical parameters are used to investigate the anisotropy of the alloy and predict its formability by determining the corresponding R-values and Hill yield coefficients.Reflection on the Measurement and Use of the Topography of the Indentation Imprint
http://hdl.handle.net/10985/9671
Reflection on the Measurement and Use of the Topography of the Indentation Imprint
MARTEAU, Julie; BIGERELLE, Maxence; BOUVIER, Salima; IOST, Alain
The goal of this paper is to study the main uses of the residual imprint of the indentation test. It also discusses the different technologies and methods employed in this context. The difficulties encountered when trying to exploit the full potentials of the imprint are thoroughly examined. A survey of the literature on the quantification of the pile-up clearly shows that there is a lack of consensus on the measurement of the residual imprint as well as on treatment methods. Therefore, in order to widen the application fields of the indentation residual imprint, relevant and standardized indicators should be established.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/96712014-01-01T00:00:00ZMARTEAU, JulieBIGERELLE, MaxenceBOUVIER, SalimaIOST, AlainThe goal of this paper is to study the main uses of the residual imprint of the indentation test. It also discusses the different technologies and methods employed in this context. The difficulties encountered when trying to exploit the full potentials of the imprint are thoroughly examined. A survey of the literature on the quantification of the pile-up clearly shows that there is a lack of consensus on the measurement of the residual imprint as well as on treatment methods. Therefore, in order to widen the application fields of the indentation residual imprint, relevant and standardized indicators should be established.Parameter identification of advanced plastic potentials and impact on plastic anisotropy prediction
http://hdl.handle.net/10985/9934
Parameter identification of advanced plastic potentials and impact on plastic anisotropy prediction
RABAHALLAH, Meziane; BALAN, Tudor; BOUVIER, Salima; BACROIX, Brigitte; BARLAT, Frédéric; CHUNG, Kwansoo; TEODOSIU, Cristian
In the work presented in this paper, several strain rate potentials are examined in order to analyze their ability to model the initial stress and strain anisotropy of several orthotropic sheet materials. Classical quadratic and more advanced non-quadratic strain rate potentials are investigated in the case of FCC and BCC polycrystals. Different identifications procedures are proposed, which are taking into account the crystallographic texture and/or a set of mechanical test data in the determination of the material parameters.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10985/99342009-01-01T00:00:00ZRABAHALLAH, MezianeBALAN, TudorBOUVIER, SalimaBACROIX, BrigitteBARLAT, FrédéricCHUNG, KwansooTEODOSIU, CristianIn the work presented in this paper, several strain rate potentials are examined in order to analyze their ability to model the initial stress and strain anisotropy of several orthotropic sheet materials. Classical quadratic and more advanced non-quadratic strain rate potentials are investigated in the case of FCC and BCC polycrystals. Different identifications procedures are proposed, which are taking into account the crystallographic texture and/or a set of mechanical test data in the determination of the material parameters.Time integration scheme for elastoplastic models based on anisotropic strain-rate potentials
http://hdl.handle.net/10985/9908
Time integration scheme for elastoplastic models based on anisotropic strain-rate potentials
RABAHALLAH, Meziane; BALAN, Tudor; BOUVIER, Salima; TEODOSIU, Cristian
Modelling of plastic anisotropy requires the definition of stress potentials (coinciding with the yield criteria in case of the associated flow rules) or, alternatively, plastic strain-rate potentials. The latter approach has several advantages whenever material parameters are determined by means of texture measurements and crystal plasticity simulations. This paper deals with a phenomenological description of anisotropy in elastoplastic rate-insensitive models, by using strain-rate potentials. A fully implicit time integration algorithm is developed in this framework and implemented in a static-implicit finite element code. Algorithmic details are discussed, including the derivation of the consistent (algorithmic) tangent modulus and the numerical treatment of the yield condition. Typical sheet-forming applications are simulated with the proposed implementation, using the recent non-quadratic strain-rate potential Srp2004-18p. Numerical simulations are carried out for materials that exhibit strong plastic anisotropy. The numerical results confirm that the presented algorithm exhibits the same generality, robustness, accuracy, and time-efficiency as state-of-the-art yield-criterion-based algorithms.
Thu, 01 Jan 2009 00:00:00 GMThttp://hdl.handle.net/10985/99082009-01-01T00:00:00ZRABAHALLAH, MezianeBALAN, TudorBOUVIER, SalimaTEODOSIU, CristianModelling of plastic anisotropy requires the definition of stress potentials (coinciding with the yield criteria in case of the associated flow rules) or, alternatively, plastic strain-rate potentials. The latter approach has several advantages whenever material parameters are determined by means of texture measurements and crystal plasticity simulations. This paper deals with a phenomenological description of anisotropy in elastoplastic rate-insensitive models, by using strain-rate potentials. A fully implicit time integration algorithm is developed in this framework and implemented in a static-implicit finite element code. Algorithmic details are discussed, including the derivation of the consistent (algorithmic) tangent modulus and the numerical treatment of the yield condition. Typical sheet-forming applications are simulated with the proposed implementation, using the recent non-quadratic strain-rate potential Srp2004-18p. Numerical simulations are carried out for materials that exhibit strong plastic anisotropy. The numerical results confirm that the presented algorithm exhibits the same generality, robustness, accuracy, and time-efficiency as state-of-the-art yield-criterion-based algorithms.Dislocation-based model for the prediction of the behavior of b.c.c. materials – grain size and strain path effects
http://hdl.handle.net/10985/9893
Dislocation-based model for the prediction of the behavior of b.c.c. materials – grain size and strain path effects
CARVALHO RESENDE, Tales; BOUVIER, Salima; ABED-MERAIM, Farid; BALAN, Tudor; SABLIN, Simon-Serge
Sheet metal forming processes involve multi-axial strain paths. For the numerical simulation of such processes, an appropriate constitutive model that properly describes material behavior at large strain is required. For accurate and time-effective simulations, it is crucial to use plasticity models based on physics, as material macroscopic behavior is closely related to the evolution of the associated microstructures. Accordingly, a large strain work-hardening phenomenological model that incorporates the intragranular microstructure evolution through a dislocation density approach is proposed. The model is defined by a yield criterion and hardening laws that are all grain-size dependent. The classical Hill criterion in which grain-size dependency was introduced is proposed. Hardening laws are given by a combination of kinematic and isotropic contributions that respectively take into account the evolution with strain of cell blocks formed by geometrically necessary boundaries (GNBs) and individual dislocation cells delineated by incidental dislocation boundaries within cell blocks (IDBs). On the one hand, IDBs evolution contribution is described by a modified Rauch et al. isotropic model, which is able to describe work-hardening stagnation and work-softening. On the other hand, GNBs evolution contribution is described by a grain-size dependent tensorial back-stress expression proposed by Aouafi et al. [2007] to describe the plastic anisotropy and Bauschinger effect. Moreover, the proposed model aims to accurately predict steel behavior through an innovative approach by only changing few “simply measurable” microstructure data (e.g. chemical composition, grain size…). The predictive capabilities of the model are assessed for interstitial free (IF) and dual phase (DP) steels with grain sizes varying respectively in the 8-40 µm and 1-10 µm value range. Different loading paths are analyzed, namely the uniaxial tensile test, reversal simple shear and orthogonal tests.
Tue, 01 Jan 2013 00:00:00 GMThttp://hdl.handle.net/10985/98932013-01-01T00:00:00ZCARVALHO RESENDE, TalesBOUVIER, SalimaABED-MERAIM, FaridBALAN, TudorSABLIN, Simon-SergeSheet metal forming processes involve multi-axial strain paths. For the numerical simulation of such processes, an appropriate constitutive model that properly describes material behavior at large strain is required. For accurate and time-effective simulations, it is crucial to use plasticity models based on physics, as material macroscopic behavior is closely related to the evolution of the associated microstructures. Accordingly, a large strain work-hardening phenomenological model that incorporates the intragranular microstructure evolution through a dislocation density approach is proposed. The model is defined by a yield criterion and hardening laws that are all grain-size dependent. The classical Hill criterion in which grain-size dependency was introduced is proposed. Hardening laws are given by a combination of kinematic and isotropic contributions that respectively take into account the evolution with strain of cell blocks formed by geometrically necessary boundaries (GNBs) and individual dislocation cells delineated by incidental dislocation boundaries within cell blocks (IDBs). On the one hand, IDBs evolution contribution is described by a modified Rauch et al. isotropic model, which is able to describe work-hardening stagnation and work-softening. On the other hand, GNBs evolution contribution is described by a grain-size dependent tensorial back-stress expression proposed by Aouafi et al. [2007] to describe the plastic anisotropy and Bauschinger effect. Moreover, the proposed model aims to accurately predict steel behavior through an innovative approach by only changing few “simply measurable” microstructure data (e.g. chemical composition, grain size…). The predictive capabilities of the model are assessed for interstitial free (IF) and dual phase (DP) steels with grain sizes varying respectively in the 8-40 µm and 1-10 µm value range. Different loading paths are analyzed, namely the uniaxial tensile test, reversal simple shear and orthogonal tests.Effect of surface roughness in the determination of the mechanical properties of material using nanoindentation test
http://hdl.handle.net/10985/9660
Effect of surface roughness in the determination of the mechanical properties of material using nanoindentation test
XIA, Yang; BIGERELLE, Maxence; MARTEAU, Julie; MAZERAN, Pierre-Emmanuel; BOUVIER, Salima; IOST, Alain
A quantitative model is proposed for the estimation of macro-hardness using nanoindentation tests. It decreases the effect of errors related to the non-reproducibility of the nanoindentation test on calculations of macro-hardness by taking into account the indentation size effect and the surface roughness. The most innovative feature of this model is the simultaneous statistical treatment of all the nanoindentation loading curves. The curve treatment mainly corrects errors in the zero depth determination by correlating their positions through the use of a relative reference. First, the experimental loading curves are described using the Bernhardt law. The fitted curves are then shifted, in order to simultaneously reduce the gaps between them that result from the scatter in the experimental curves. A set of shift depths, Δhc, is therefore identified. The proposed approach is applied to a large set of TiAl6V4 titanium-based samples with different roughness levels, polished by eleven silicon carbide sandpapers from grit paper 80 to 4,000. The result reveals that the scatter degree of the indentation curves is higher when the surface is rougher. The standard deviation of the shift Δhc is linearly connected to the standard deviation of the surface roughness, if the roughness is high-pass filtered in the scale of the indenter (15 µm). Using the proposed method, the estimated macro-hardness for eleven studied TiAl6V4 samples is in the range of 3.5–4.1 GPa, with the smallest deviation around 0.01 GPa, which is more accurate than the one given by the Nanoindentation MTS™ system, which uses an average value (around 4.3 ± 0.5 GPa). Moreover, the calculated Young's modulus of the material is around 136 ± 20 GPa, which is similar to the modulus in literature.
Wed, 01 Jan 2014 00:00:00 GMThttp://hdl.handle.net/10985/96602014-01-01T00:00:00ZXIA, YangBIGERELLE, MaxenceMARTEAU, JulieMAZERAN, Pierre-EmmanuelBOUVIER, SalimaIOST, AlainA quantitative model is proposed for the estimation of macro-hardness using nanoindentation tests. It decreases the effect of errors related to the non-reproducibility of the nanoindentation test on calculations of macro-hardness by taking into account the indentation size effect and the surface roughness. The most innovative feature of this model is the simultaneous statistical treatment of all the nanoindentation loading curves. The curve treatment mainly corrects errors in the zero depth determination by correlating their positions through the use of a relative reference. First, the experimental loading curves are described using the Bernhardt law. The fitted curves are then shifted, in order to simultaneously reduce the gaps between them that result from the scatter in the experimental curves. A set of shift depths, Δhc, is therefore identified. The proposed approach is applied to a large set of TiAl6V4 titanium-based samples with different roughness levels, polished by eleven silicon carbide sandpapers from grit paper 80 to 4,000. The result reveals that the scatter degree of the indentation curves is higher when the surface is rougher. The standard deviation of the shift Δhc is linearly connected to the standard deviation of the surface roughness, if the roughness is high-pass filtered in the scale of the indenter (15 µm). Using the proposed method, the estimated macro-hardness for eleven studied TiAl6V4 samples is in the range of 3.5–4.1 GPa, with the smallest deviation around 0.01 GPa, which is more accurate than the one given by the Nanoindentation MTS™ system, which uses an average value (around 4.3 ± 0.5 GPa). Moreover, the calculated Young's modulus of the material is around 136 ± 20 GPa, which is similar to the modulus in literature.