Simulation of sub-micron indentation tests with spherical and Berkovich indenters

2001 ◽  
Vol 16 (7) ◽  
pp. 2149-2157 ◽  
Author(s):  
A. C. Fischer-Cripps
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Material Properties ◽  
Indentation Testing ◽  
Depth Sensing ◽  
Displacement Response ◽  
Analysis Methods ◽  
Detailed Treatment ◽  
Indentation Tests ◽  
Load Displacement

The present work is concerned with the methods of simulation of data obtained from depth-sensing submicron indentation testing. Details of analysis methods for both spherical and Berkovich indenters using multiple or single unload points are presented followed by a detailed treatment of a method for simulating an experimental load–displacement response where the material properties such as elastic modulus and hardness are given as inputs. A comparison between simulated and experimental data is given.

Use of combined elastic modulus in depth-sensing indentation with a conical indenter

2003 ◽  
Vol 18 (5) ◽  
pp. 1043-1045 ◽  
Author(s):  
A. C. Fischer-Cripps
Keyword(s):  
Elastic Modulus ◽  
Test Data ◽  
Data Use ◽  
Indentation Test ◽  
Indentation Testing ◽  
Depth Sensing ◽  
Conical Indenter ◽  
Displacement Response ◽  
Conventional Methods ◽  
Elastic Unloading

Conventional methods of analysis for depth-sensing indentation test data use the slope of the elastic unloading portion of the load–displacement response in conjunction with the elastic equations of contact for a rigid cone. It is common practice to incorporate the combined modulus of the indenter and specimen in these equations although the validity of this practice never appears to have been verified. This work demonstrates the validity of using the combined elastic modulus in depth-sensing indentation testing in conjunction with the elastic equations of contact for a conical indenter.

An elastic-plastic indentation model and its solutions

1996 ◽  
Vol 11 (9) ◽  
pp. 2358-2367 ◽  
Author(s):  
Weiping Yu ◽  
James P. Blanchard
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Material Properties ◽  
Hardness Test ◽  
Plastic Materials ◽  
Indentation Tests ◽  
Plastic Indentation ◽  
Comparison With Experimental Data

An analytical model of hardness has been developed. Four major indentation tests, namely indentation by cones, wedges, spheres, and flat-ended, axisymmetric cylinders have been analyzed based on the model. Analytical relationships among hardness, yield stress, elastic modulus, Poisson's ratio, and indenter geometries have been found. These results enable hardness to be calculated in terms of uniaxial material properties and indenter geometries for a wide variety of elastic and plastic materials. These relationships can also be used for evaluating other mechanical properties through hardness measurements and for converting hardness from one type of hardness test into those of a different test. Comparison with experimental data and numerical calculations is excellent.

Study of analysis methods of depth-sensing indentation test data for spherical indenters

2001 ◽  
Vol 16 (6) ◽  
pp. 1579-1584 ◽  
Author(s):  
A. C. Fischer-Cripps
Keyword(s):  
Elastic Modulus ◽  
Test Data ◽  
Indentation Test ◽  
Spherical Indenter ◽  
Depth Sensing ◽  
Formal Treatment ◽  
Underlying Theory ◽  
Analysis Methods ◽  
Load Displacement

The underlying theory behind the extraction of elastic modulus and hardness from the unloading load–displacement data obtained with a spherical indenter was explored in detail. A formal treatment of the effect of indenter elasticity was given, and the validity of the use of the reduced or combined modulus in analytical treatments was verified. The “Oliver and Pharr” method and the “Field and Swain” methods of analyses were compared in detail and shown to be equivalent.

scholarly journals Analysis of depth-sensing indentation tests with a Knoop indenter

2001 ◽  
Vol 16 (6) ◽  
pp. 1660-1667 ◽  
Author(s):  
L. Riester ◽  
T. J. Bell ◽  
A. C. Fischer-Cripps
Keyword(s):  
Elastic Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
New Method ◽  
Short Axis ◽  
Depth Sensing ◽  
Specimen Material ◽  
Indentation Tests ◽  
Conventional Methods ◽  
Knoop Indenter

The present work shows how data obtained in a depth-sensing indentation test using a Knoop indenter may be analyzed to provide elastic modulus and hardness of the specimen material. The method takes into account the elastic recovery along the direction of the short axis of the residual impression as the indenter is removed. If elastic recovery is not accounted for, the elastic modulus and hardness are overestimated by an amount that depends on the ratio of E/H of the specimen material. The new method of analysis expresses the elastic recovery of the short diagonal of the residual impression into an equivalent face angle for one side of the Knoop indenter. Conventional methods of analysis using this corrected angle provide results for modulus and hardness that are consistent with those obtained with other types of indenters.

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.

Influence of the Microstructure on Macro/Micro versus Nanohardness of SiC Ceramics

2014 ◽  
Vol 606 ◽  
pp. 197-200 ◽  
Author(s):  
Alexandra Kovalčíková ◽  
Ján Dusza ◽  
Pavol Šajgalík
Keyword(s):  
Silicon Carbide ◽  
Elastic Modulus ◽  
Liquid Phase ◽  
Grain Growth ◽  
Depth Sensing ◽  
Sic Ceramics ◽  
Peak Loads ◽  
Heat Treated ◽  
Indentation Tests ◽  
Sintered Silicon

The influence of microstructural variations on the macro/microhardness, nanohardness and Young`s modulus of liquid phase sintered silicon carbide (LPS SiC) has been observed. In order to modify the microstructures some samples were further heat treated at 1850°C for 5 hours to promote grain growth. The depth-sensing indentation tests of SiC materials were performed at several peak loads in the range 10-400 mN. For a better assessment, the indentation values of hardness and Young`s modulus modulus of SiC matrix were also compared to the hardness and Elastic modulus of individual SiC grains. The comparison of macro/micro and nanohardness showed that nanohardness was significantly higher, generally by 6-7 GPa. The nanohardness of individual plate-like SiC grains was around 2 GPa higher than nanohardness of SiC matrix.

Interface Transition Zone and the Elastic Modulus of Cement-Based Composites

1994 ◽  
Vol 370 ◽  
Author(s):  
Peter I. Simeonov ◽  
S.H. Ahmad
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Transition Zone ◽  
Material Properties ◽  
General Trend ◽  
Two Phase ◽  
Interface Transition Zone ◽  
The Matrix ◽  
Approach Zero ◽  
Highly Porous

AbstractThe influence of the Interface Transition Zone (ITZ) on the elastic modulus of concrete is demonstrated as a divergence of the experimental data from the general trend of the theoretical Hashin-Shtrikman bounds. This divergence is well related to the W/C of the composite. With reduction of W/C the influence of ITZ decreases and for values close to 0.4 and lower it is insignificant.The formation of the ITZ is characterized by a transfer of water from the matrix to the surface of the aggregates. As a result of this a highly porous ITZ is formed while the matrix remains with a reduced porosity. This process can also be described as a transfer of material properties. For some compositions the balance of this transfer can approach zero. The imbalance in this process is more pronounced at higher W/C.The effect of Interface Transition Zone can be successfully simulated by the help of recently derived Hashin's variational bounds for two-phase composites with imperfect interfaces.

scholarly journals A Viscoelastic Constitutive Model Can Accurately Represent Entire Creep Indentation Tests of Human Patella Cartilage

2013 ◽  
Vol 29 (3) ◽  
pp. 292-302 ◽  
Author(s):  
Kathryn E. Keenan ◽  
Saikat Pal ◽  
Derek P. Lindsey ◽  
Thor F. Besier ◽  
Gary S. Beaupre
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Material Properties ◽  
Viscoelastic Model ◽  
Element Model ◽  
Finite Element Models ◽  
Short Term ◽  
Biphasic Model ◽  
Experimental Creep ◽  
Indentation Tests

Cartilage material properties provide important insights into joint health, and cartilage material models are used in whole-joint finite element models. Although the biphasic model representing experimental creep indentation tests is commonly used to characterize cartilage, cartilage short-term response to loading is generally not characterized using the biphasic model. The purpose of this study was to determine the short-term and equilibrium material properties of human patella cartilage using a viscoelastic model representation of creep indentation tests. We performed 24 experimental creep indentation tests from 14 human patellar specimens ranging in age from 20 to 90 years (median age 61 years). We used a finite element model to reproduce the experimental tests and determined cartilage material properties from viscoelastic and biphasic representations of cartilage. The viscoelastic model consistently provided excellent representation of the short-term and equilibrium creep displacements. We determined initial elastic modulus, equilibrium elastic modulus, and equilibrium Poisson’s ratio using the viscoelastic model. The viscoelastic model can represent the short-term and equilibrium response of cartilage and may easily be implemented in whole-joint finite element models.

Influences of pileup on the measurement of mechanical properties by load and depth sensing indentation techniques

1998 ◽  
Vol 13 (4) ◽  
pp. 1049-1058 ◽  
Author(s):  
A. Bolshakov ◽  
G. M. Pharr
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Indentation Load ◽  
Depth Sensing ◽  
Element Mesh ◽  
Plastic Materials ◽  
Element Simulation ◽  
Load Displacement ◽  
Elastic Plastic Materials ◽  
True Contact

Finite element simulation of conical indentation of a wide variety of elastic-plastic materials has been used to investigate the influences of pileup on the accuracy with which hardness and elastic modulus can be measured by load and depth-sensing indentation techniques. The key parameter in the investigation is the contact area, which can be determined from the finite element results either by applying standard analysis procedures to the simulated indentation load-displacement data, as would be done in an experiment, or more directly, by examination of the contact profiles in the finite element mesh. Depending on the pileup behavior of the material, these two areas may be very different. When pileup is large, the areas deduced from analyses of the load-displacement curves underestimate the true contact areas by as much as 60%. This, in turn, leads to overestimations of the hardness and elastic modulus. The conditions under which the errors are significant are identified, and it is shown how parameters measured from the indentation load-displacement data can be used to identify when pileup is an important factor.

Effect of Indenter Geometries on Material Properties: A Finite Element Simulation

2011 ◽  
Vol 70 ◽  
pp. 219-224 ◽  
Author(s):  
J.J. Kang ◽  
A.A. Becker ◽  
W. Sun
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Finite Element Simulation ◽  
Material Properties ◽  
Plastic Strains ◽  
Fe Simulations ◽  
Element Simulation ◽  
Different Types ◽  
Indentation Tests

In this study, numerical indentation tests are carried out to examine the sensitivity of FE solutions with respect to different types of substrate models. Axisymmetric, 3D-quarter and 3D-half geometry substrates with a perfectly sharp indenter are modelled. Numerical evaluations of three different indenters, namely Berkovich, Vickers and conical indenters with perfectly sharp tips are investigated. From the FE simulations, the loading-unloading curves can be obtained. From the slope of the unloading curve, the hardness and elastic modulus can be calculated by using the Oliver-Pharr method. The results are compared to investigate the effects of using different indenter geometries. The equivalent plastic strains and the effects of different face angles of the indenters are analysed.

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