scholarly journals Numerical verification for instrumented spherical indentation techniques in determining the plastic properties of materials

2009 ◽  
Vol 24 (12) ◽  
pp. 3653-3663 ◽  
Author(s):  
Taihua Zhang ◽  
Peng Jiang ◽  
Yihui Feng ◽  
Rong Yang
Keyword(s):  
Numerical Experiments ◽  
Spherical Indentation ◽  
Numerical Verification ◽  
Instrumented Indentation ◽  
Plastic Properties ◽  
Wide Range ◽  
Validity Range ◽  
Indentation Tests ◽  
Properties Of Materials ◽  
Indentation Methods

Instrumented indentation tests have been widely adopted for elastic modulus determination. Recently, a number of indentation-based methods for plastic properties characterization have been proposed, and rigorous verification is absolutely necessary for their wide application. In view of the advantages of spherical indentation compared with conical indentation in determining plastic properties, this study mainly concerns verification of spherical indentation methods. Five convenient and simple models were selected for this purpose, and numerical experiments for a wide range of materials are carried out to identify their accuracy and sensitivity characteristics. The verification results show that four of these five methods can give relatively accurate and stable results within a certain material domain, which is defined as their validity range and has been summarized for each method.

Local Mechanical Characterization of Metal Foams by Nanoindentation

2015 ◽  
Vol 662 ◽  
pp. 59-62 ◽  
Author(s):  
Jiří Němeček ◽  
Vlastimil Kralik
Keyword(s):  
Cell Walls ◽  
Plastic Material ◽  
Spherical Indentation ◽  
Isotropic Hardening ◽  
Plastic Properties ◽  
Macro Scale ◽  
Static Indentation ◽  
Indentation Tests ◽  
Constitutive Parameters

This paper deals with microstructure and micromechanical properties of two commercially available aluminium foams (Alporas and Aluhab). Since none of the materials is available in a bulk and standard mechanical testing at macro-scale is not possible the materials need to be tested at micro-scale. To obtain both elastic and plastic properties quasi-static indentation was performed with two different indenter geometries (Berkovich and spherical tips). The material phase properties were analyzed with statistical grid indentation method and micromechanical homogenization was applied to obtain effective elastic wall properties. In addition, effective inelastic properties of cell walls were identified with spherical indentation. Constitutive parameters related to elasto-plastic material with linear isotropic hardening (the yield point and tangent modulus) were directly deduced from the load–depth curves of spherical indentation tests using formulations of the representative strain and stress introduced by Tabor.

scholarly journals Determination of the Plastic Strain by Spherical Indentation of Uniaxially Deformed Sheet Metals

2015 ◽  
Vol 651-653 ◽  
pp. 950-956 ◽  
Author(s):  
Mohamad Idriss ◽  
Olivier Bartier ◽  
Gérard Mauvoisin ◽  
Charbel Moussa ◽  
Eddie Gazo Hanna ◽  
...  
Keyword(s):  
Plastic Strain ◽  
Accurate Determination ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Spherical Indentation ◽  
Instrumented Indentation ◽  
Forming Process ◽  
Hardening Law ◽  
Indentation Tests

This work consists of determining the plastic strain value undergone by a material during a forming process using the instrumented indentation technique (IIT). A deep drawing steel DC01 is characterized using tensile, shear and indentation tests. The plastic strain value undergone by this steel during uniaxial tensile tests is determined by indentation. The results show that, the identification from IIT doesn’t lead to an accurate value of the plastic strain if the assumption that the hardening law follows Hollomon law is used. By using a F.E. method, it is shown that using a Voce hardening law improves significantly the identification of the hardening law of a pre-deformed material. Using this type of hardening law coupled to a methodology based on the IIT leads to an accurate determination of the hardening law of a pre-deformed material. Consequently, this will allow determining the plastic strain value and the springback elastic strain value of a material after a mechanical forming operation.

MATERIAL CHARACTERIZATION BASED ON INSTRUMENTED AND SIMULATED INDENTATION TESTS

2009 ◽  
Vol 01 (01) ◽  
pp. 61-84 ◽  
Author(s):  
ZISHUN LIU ◽  
EDY HARSONO ◽  
SOMSAK SWADDIWUDHIPONG
Keyword(s):  
Neural Network ◽  
Material Properties ◽  
Indentation Test ◽  
Network Models ◽  
Spherical Indentation ◽  
Instrumented Indentation ◽  
Neural Network Models ◽  
Advantages And Disadvantages ◽  
Indentation Tests ◽  
Load Displacement

This paper reviews various techniques to characterize material by interpreting load-displacement data from instrumented indentation tests. Scaling and dimensionless analysis was used to generalize the universal relationships between the characteristics of indentation curves and their material properties. The dimensionless functions were numerically calibrated via extensive finite element analysis. The interpretation of load-displacement curves from the established relationships was thus carried out by either solving higher order functions iteratively or employing neural networks. In this study, the advantages and disadvantages of these techniques are highlighted. Several issues in an instrumented indentation test such as friction, size effect and uniqueness of reverse analysis algorithms are discussed. In this study, a new reverse algorithm via neural network models to extract the mechanical properties by dual Berkovich and spherical indentation tests is introduced. The predicted material properties based on the proposed neural network models agree well with the numerical input data.

Determination of the proof strength and flow properties of materials from spherical indentation tests: An analytical approach based on the expanding cavity model

2018 ◽  
Vol 53 (4) ◽  
pp. 225-241 ◽  
Author(s):  
Tairui Zhang ◽  
Shang Wang ◽  
Weiqiang Wang
Keyword(s):  
Finite Element ◽  
Calculation Method ◽  
Force Balance ◽  
Spherical Indentation ◽  
Cavity Model ◽  
Flow Properties ◽  
Finite Element Calculations ◽  
Indentation Tests ◽  
Properties Of Materials ◽  
Proof Strength

An analytical method based on the extended expanding cavity model was proposed in this study to determine the proof strength Rp0.2 and flow properties of materials that obey the Johnson–Cook constitutive model from spherical indentation tests. The introduction of the Johnson–Cook model made the proposed method suitable for the tensile property evaluation of materials not only at room temperature but also at elevated temperatures. The validity of the expanding cavity model was verified through comparisons of von Mises equivalent strain distributions obtained from finite element analyses with the corresponding results from theoretical analysis. From the parameter analysis, it was found that the indentation governing parameter ψempirical in the empirical method was actually determined by the tangential modulus Ep and the hardening exponent n and thus should not be considered as a constant. We also analyzed the unreliability of previous plastic zone radius rp calculation method at large indentation depths (with obvious pileup phenomenon) and put forward a new calculation method of rp based on the force balance. Finite element calculations of spherical indentation tests with tensile properties of Ti6Al4V and AISI 4340 were conducted in this study as substitutes for spherical indentation tests. The load–depth data and rp from finite element calculations were employed in the reverse analysis, the results of which showed that spherical indentation tests can provide the same reliable Rp0.2 as tensile tests and even the whole stress–strain curves. Furthermore, the influence of friction and the measuring system strain threshold in the measurement of rp, which may be inevitable in experiments, were also thoroughly discussed in this study, which also helped to verify the robustness of this study.

Application of a portable indentation rig with Rockwell indenter to determine mechanical properties and residual stresses on an aluminum plate

2020 ◽  
Vol 55 (7-8) ◽  
pp. 246-257
Author(s):  
Saba Salmani Ghanbari ◽  
Amir-Hossein Mahmoudi
Keyword(s):  
Mechanical Properties ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Indentation Load ◽  
Instrumented Indentation ◽  
Unknown Parameters ◽  
Plastic Properties ◽  
Wide Range ◽  
Portable Apparatus ◽  
Non Destructive

Measuring residual stresses is still a dilemma in many engineering applications. It is even more crucial when the industrial requirements demand for a non-destructive technique in order to avoid compromising the structural integrity of the engineering components. Furthermore, estimating the mechanical properties of the materials, especially when the components are aged, is of importance. Instrumented indentation has gained much interest in recent years. There are many studies in the literature which are focused on measuring residual stresses or mechanical properties using instrumented indentation. Since in many cases there is no possibility of transferring large samples or those under service, for possible measurements, having a portable rig can be very useful. Furthermore, indentation procedure is a low-cost non-destructive method with high accuracy which is able to measure the plastic properties of material as well as its residual stresses on which the designing and construction of the portable apparatus were based. The instrumented indentation testing details were followed according to the ASTM E2546-15 standard practice. In this research, a wide range of simulations were performed on a group of aluminum alloys in order to estimate the equi-biaxial residual stresses by analyzing the indentation load–displacement curves which were obtained from the experimental outcomes. Then neural networks were employed to estimate the unknown parameters. The performance accuracy of the designed portable apparatus and the acceptable precision of the introduced method were then verified with experimental tests performed on Al 2024-T351.

Small Scale Plastic Yielding of Mg Alloys Assessed with Nanoindentation

2020 ◽  
Vol 405 ◽  
pp. 339-344
Author(s):  
Jiří Němeček ◽  
Jan Maňák ◽  
Jiří Němeček
Keyword(s):  
Focused Ion Beam ◽  
Electron Backscatter Diffraction ◽  
Ion Beam ◽  
Az31 Alloy ◽  
Small Scale ◽  
Spherical Indentation ◽  
Plastic Properties ◽  
Indentation Tests ◽  
Order Of Magnitude ◽  
Volume Characteristics

The paper investigates deformations and plastic properties received from different material volumes and tests of magnesium samples. Small volume characteristics gained on single Mg crystals are compared to polycrystalline AZ31 alloy. Results of tests employing nanoindentation, focused ion beam milling and electron backscatter diffraction techniques are presented. Large differences were found between micro-beam testing and spherical indentation tests having the volume one order of magnitude apart. The plastic strength scaling factor was found 1.7 for the studied grain configurations and volumes.

A Novel Method to Extract the Plastic Properties of Metal Materials from a Continuous Spherical Indentation Test

2017 ◽  
Vol 734 ◽  
pp. 206-211 ◽  
Author(s):  
Zhuang Jin ◽  
Jian Ping Zhao
Keyword(s):  
Strain Hardening ◽  
Indentation Test ◽  
New Method ◽  
Spherical Indentation ◽  
Strain Hardening Exponent ◽  
Computational Results ◽  
Plastic Properties ◽  
Novel Method ◽  
Properties Of Materials ◽  
Metal Materials

Cao and Lu had built a method to acquire the properties of materials. But they neglected the influence of strain hardening exponent n by introducing the representative strain which didan’t have any physical meaning. A new method from a continuous spherical indentation test was built, the influence of strain hardening exponent n were considered and the formulas of dimensionless functions defined in their work were improved in this present paper. Then the computational results from the new method and the actual results were compared and the error is about 8%.

On the sensitivity characteristics in the determination of the elastic and plastic properties of materials through multiple indentation

2007 ◽  
Vol 22 (4) ◽  
pp. 1043-1063 ◽  
Author(s):  
Hongzhi Lan ◽  
T.A. Venkatesh
Keyword(s):  
Spherical Indentation ◽  
Plastic Properties ◽  
Reverse Analysis ◽  
Properties Of Materials ◽  
Sharp Indentation ◽  
Comprehensive Study

A comprehensive study of the sensitivity characteristics associated with the determination of the elasto-plastic properties of a large number of materials using several combinations of dual, triple, and quadruple sharp indentation, and spherical indentation illustrates that: (i) The lowest sensitivity to the determination of plastic properties is observed for the indenter combination that corresponds either to the largest difference in the corresponding representative stresses or the largest difference in the indenter apex angles. (ii) The triple or quadruple sharp indenter combinations considered in the present study do not show a significant improvement in the sensitivity characteristics when compared to that of the dual sharp indentation. (iii) In the determination of plastic properties through spherical indentation where two representative stresses are invoked, the highest and the lowest sensitivity, respectively, are observed for the combinations in which the differences in the representative stresses are the lowest and the highest. The sensitivity is further reduced if a large number of representative stresses are considered for the reverse analysis.

Comments on “Extracting the plastic properties of metal materials from microindentation tests: Experimental comparison of recently published methods” by B. Guelorget, et al. [J. Mater. Res. 22, 1512 (2007)]: The correct methods of analyzing experimental data and reverse analysis of indentation tests

2008 ◽  
Vol 23 (3) ◽  
pp. 598-608 ◽  
Author(s):  
Nagahisa Ogasawara ◽  
Manhong Zhao ◽  
Norimasa Chiba ◽  
Xi Chen
Keyword(s):  
Experimental Data ◽  
Experimental Comparison ◽  
Experiment Data ◽  
Plastic Properties ◽  
Acta Mater ◽  
Indentation Tests ◽  
Scripta Mater ◽  
Reverse Analysis ◽  
Metal Materials ◽  
Indentation Methods

Based on microindentation experiments of three different metals, Guelorget et al. [J. Mater. Res. 22, 1512 (2007)] have compared the performance of five different indentation methods on extracting material plastic properties—among them, three papers were proposed by Cao and Lu [Acta Mater.52, 4023 (2004); J. Mater. Res.20, 1194 (2005); J. Mech. Phys. Solids53, 49 (2005)] and two papers were published by our group [Ogasawara et al., Scripta Mater.54, 65 (2006); Zhao et al. Acta Mater.54, 23 (2006)]. They argued that the performances of our techniques in [Ogasawara et al., Scripta Mater.54, 65 (2006); Zhao et al. Acta Mater.54, 23 (2006)] were quite poor. Here we show that Guelorget et al. [J. Mater. Res. 22, 1512 (2007)] have made quite a few mistakes and problematic steps when they handled the experiment data and performed reverse analysis. Indeed, the material plastic properties extracted from the correct procedures based on our papers [Ogasawara et al., Scripta Mater.54, 65 (2006); Zhao et al. Acta Mater.54, 23 (2006)] are much better and more stable than that reported in Guelorget et al. [J. Mater. Res. 22, 1512 (2007)]. Several general issues related to interpreting microindentation data and reverse analysis are also discussed, which may serve as important guidelines for similar studies in the future.

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