Energy dissipated during spherical indentation

2004 ◽  
Vol 19 (6) ◽  
pp. 1605-1607 ◽  
Author(s):  
Jürgen Malzbender
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Strain Hardening ◽  
Contact Area ◽  
Indentation Depth ◽  
Dissipated Energy ◽  
Spherical Indentation ◽  
Scaling Relationships ◽  
Energy Dissipated

A relationship is derived for spherical indentation relating the dissipated energy to the ratio of hardness to elastic modulus and the ratio of indentation depth to radius. The result agrees with recent findings obtained on the basis of scaling relationships in combination with finite element simulations. Furthermore, relationships are given for hardness, elastic modulus and contact area, which permit a determination of these properties independent of the strain hardening characteristics and independent of pileup and sink-in.

Analysis of sharp-tip-indentation load–depth curve for contact area determination taking into account pile-up and sink-in effects

2004 ◽  
Vol 19 (11) ◽  
pp. 3307-3315 ◽  
Author(s):  
Yeol Choi ◽  
Ho-Seung Lee ◽  
Dongil Kwon
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Contact Area ◽  
Indentation Depth ◽  
Indentation Load ◽  
Real Contact Area ◽  
Elastic Deflection ◽  
Contact Depth ◽  
Real Contact ◽  
Pile Up

Hardness and elastic modulus of micromaterials can be evaluated by analyzing instrumented sharp-tip-indentation load–depth curves. The present study quantified the effects of tip-blunting and pile-up or sink-in on the contact area by analyzing indentation curves. Finite-element simulation and theoretical modeling were used to describe the detailed contact morphologies. The ratio f of contact depth, i.e., the depth including elastic deflection and pile-up and sink-in, to maximum indentation depth, i.e., the depth measured only by depth sensing, ignoring elastic deflection and pile-up and sink-in, was proposed as a key indentation parameter in evaluating real contact depth during indentation. This ratio can be determined strictly in terms of indentation-curve parameters, such as loading and unloading slopes at maximum depth and the ratio of elastic indentation energy to total indentation energy. In addition, the value of f was found to be independent of indentation depth, and furthermore the real contact area can be determined and hardness and elastic modulus can be evaluated from f. This curve-analysis method was verified in finite-element simulations and nanoindentation experiments.

EFFECT OF MECHANICAL PROPERTIES OF THE SUBSTRATE TISSUES ON THE DETERMINATION OF ELASTIC MODULUS OF THE SCLERA USING INDENTATION TEST

2016 ◽  
Vol 16 (07) ◽  
pp. 1650085
Author(s):  
XIUQING QIAN ◽  
KUNYA ZHANG ◽  
ZHICHENG LIU
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Elastic Moduli ◽  
Indentation Depth ◽  
Vitreous Body ◽  
Indentation Test ◽  
Posterior Pole

The sclera is an important connective tissue that protects the sensitive layers within the eyeball. Identifying the mechanical properties of the sclera near the posterior pole is necessary to analyze the deformation of the sclera and stresses changing in the optic nerve head tissues. We propose a method to determine the mechanical properties of the sclera using dimensional analysis, finite element method and the indentation test. The elastic moduli of the sclera for different indentation depths and positions were identified. We found that the elastic moduli of the sclera varied with indentation depth. This was due to the effect of the mechanical properties of the substrate tissues inside the sclera. The elastic modulus of the choroid had the biggest effect on the determination of elastic modulus of the sclera, whereas that of the vitreous body could be ignored when the ratio of the indentation depth to the thickness of the sclera was less than 0.5. The effects of mechanical properties of the substrate tissues become more pronounced at greater indentation depths.

Effect of Crystallographic Orientation on Nanoindentation Response of Fe3Si Single-Crystals

2018 ◽  
Vol 784 ◽  
pp. 44-48 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Aleš Materna
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Shear Stress ◽  
Contact Area ◽  
Measured Data ◽  
Deformation Mechanisms ◽  
Spherical Indentation ◽  
Indentation Modulus ◽  
Slip Systems ◽  
Correct Interpretation

Deformation mechanisms and mechanical properties of Fe3(wt.%)Si single crystal in two different orientations were investigated by spherical indentation. For correct interpretation of measured data and better understanding of the deformation mechanisms under the contact area, finite element simulations were carried out and resolved shear stress in available slip systems was computed. Pop-in behavior, differences in hardness, indentation modulus and shapes of residual imprints were observed and associated with different activation of slip.

Comment on the determination of mechanical properties from the energy dissipated during indentation

2005 ◽  
Vol 20 (5) ◽  
pp. 1090-1092 ◽  
Author(s):  
Jürgen Malzbender
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Total Energy ◽  
Energy Dissipated

Based on a comparison of relationships between the energy dissipated during indentation and the ratio of hardness to elastic modulus, a procedure is outlined to determine hardness and elastic modulus from the ratio of the elastic to total energy dissipated during an indentation cycle for non-ideal indenters.

Influences of stress on the measurement of mechanical properties using nanoindentation: Part II. Finite element simulations

1996 ◽  
Vol 11 (3) ◽  
pp. 760-768 ◽  
Author(s):  
A. Bolshakov ◽  
W. C. Oliver ◽  
G. M. Pharr
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Contact Area ◽  
Cylindrical Specimen ◽  
Preceding Paper ◽  
Indentation Load ◽  
The Finite Element Method ◽  
Indentation Process ◽  
Plastic Indentation ◽  
Area Determination

The finite element method has been used to study the behavior of aluminum alloy 8009 during elastic-plastic indentation to establish how the indentation process is influenced by applied or residual stress. The study was motivated by the experiments of the preceding paper which show that nanoindentation data analysis procedures underestimate indentation contact areas and therefore overestimate hardness and elastic modulus in stressed specimens. The NIKE2D finite element code was used to simulate indentation contact by a rigid, conical indenter in a cylindrical specimen to which biaxial stresses were applied as boundary conditions. Indentation load-displacement curves were generated and analyzed according to standard methods for determining hardness and elastic modulus. The simulations show that the properties measured in this way are inaccurate because pileup is not accounted for in the contact area determination. When the proper contact area is used, the hardness and elastic modulus are not significantly affected by the applied stress.

scholarly journals Determination of elastic moduli of elastic–plastic microspherical materials using nanoindentation simulation without mechanical polishing

2021 ◽  
Vol 12 ◽  
pp. 213-221
Author(s):  
Hongzhou Li ◽  
Jialian Chen
Keyword(s):  
Elastic Modulus ◽  
Elastic Moduli ◽  
Indentation Depth ◽  
Flat Surface ◽  
Computational Study ◽  
Experimental Methods ◽  
Mechanical Polishing ◽  
Initial Yield Stress ◽  
Elastic Plastic

When using the Oliver–Pharr method, the indented specimen is assumed to be a perfectly flat surface, thus ignoring the influences of surface roughness that might be encountered in experiment. For nanoindentation measurements, a flat surface is fabricated from curved specimens by mechanical polishing. However, the position of the polished curved surface cannot be controlled. There are no reliable theoretical or experimental methods to evaluate the mechanical behavior during nanoindentation of an elastic–plastic microsphere. Therefore, it is necessary to conduct reliable numerical simulations to evaluate this behavior. This article reports a systematic computational study regarding the instrumented nanoindentation of elastic–plastic microspherical materials. The ratio between elastic modulus of the microsphere and the initial yield stress of the microsphere was systematically varied from 10 to 1000 to cover the mechanical properties of most materials encountered in engineering. The simulated results indicate that contact height is unsuitable to replace contact depth for obtaining the indentation elastic modulus of microspherical materials. The extracted elastic modulus of a microsphere using the Oliver–Pharr method with the simulated unloading curve depends on the indentation depth. It demonstrates that nanoindentation on microspherical materials exhibits a “size effect”.

scholarly journals Comparative Analysis Carried Out on Modern Indentation Techniques for the Measurement of Mechanical Properties: A Review

2020 ◽  
Author(s):  
Saquib Rouf ◽  
Sobura Altaf ◽  
Shezan Malik ◽  
Kaleem Ahmad Najar
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Comparative Analysis ◽  
Contact Area ◽  
Indirect Method ◽  
Indentation Depth ◽  
Depth Of Penetration ◽  
Simple Method ◽  
Indentation Technique ◽  
Force Contact

Nowadays many indentation techniques are being commonly employed for determining some mechanical properties (harness, elastic modulus, toughness, etc.) using simple method of measuring the indentation depth. On the basis of measurement of depth of penetration, indentation technique has be classified into major categories i.e. microindentation and nanoindentation. Nanoindentation technique uses indirect method of determining the contact area as the depth of penetration is measured in nanometers, while in conventional indentation the area in contact is measured by elementary measurement of the residual area after the indenter is removed from the specimen. Dynamic hardness is the best result of dynamic indentation which can be expressed as the ratio of energy consumed during a rapid indentation to the volume of indentation. The parameter which are taken into consideration are indentation depth, contact force, contact area, mean contact pressure.

Extracting yield strength and strain-hardening exponent of metals with a double-angle indenter

2009 ◽  
Vol 24 (5) ◽  
pp. 1674-1682 ◽  
Author(s):  
Genliang Hou ◽  
Fei Wang ◽  
Kewei Xu
Keyword(s):  
Elastic Modulus ◽  
Yield Strength ◽  
Strain Hardening ◽  
Small Region ◽  
Constitutive Relationship ◽  
Strain Hardening Exponent ◽  
Yield Strain ◽  
Isotropic Metal ◽  
Wear And Corrosion Resistance

A double-angle indenter model is proposed to determine the representative strain in the indentation process, and a new method is then developed aiming at the extraction of the yield strength and strain-hardening exponent from the surface layer of metals, because surface properties, especially in a small region, may differ from bulk ones and are sometimes closer to service properties such as fatigue strength, wear, and corrosion resistance. First, the isotropic metal was analyzed, the elastic modulus of which was fixed at 128 GPa, the yield strength was 50 to 200 MPa, and the strain-hardening exponent was 0.1 to 0.5. By introducing the yield strain to substitute the yield strength in the calculation, it was proved that the model can cover the majority of metals because the introduced weight parameter λ is independent of the yield strength and the elastic modulus, although it depends on the strain-hardening exponent to some extent. For the determination of yield strain εY (or yield strength Y), the precision is better for low C/E and low n, whereas for the determination of strain-hardening exponent n, the precision is better for high C/E and low εY. By using the double-angle indenter, the material constitutive relationship at the surface can be evaluated from just one indentation without any other measurements.

Determination of Elastic Modulus and Poisson Ratio for Nanoporous Materials

2012 ◽  
Vol 466-467 ◽  
pp. 366-370
Author(s):  
Fue Han ◽  
Chang Qing Chen ◽  
Ya Peng Shen
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Elastic Modulus ◽  
Poisson Ratio ◽  
Nanoporous Materials ◽  
The Finite Element Method ◽  
Out Of Plane ◽  
Element Method

Through the finite element method, the elastic modulus and Poisson ratio out of plane of the honeycomb nanoporous materials are obtained. In the end, the values are contrasted with the scale values. Results show that the values are same to the scale values.

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