Nanoindentation by Multiple Loads Methodology: A Pile Up Correction Procedure

2007 ◽  
Vol 345-346 ◽  
pp. 805-808 ◽  
Author(s):  
Miguel Angel Garrido ◽  
Jesus Rodríguez
Keyword(s):  
Element Model ◽  
Spherical Indentation ◽  
Correction Procedure ◽  
Elastic Plastic ◽  
Multiple Loads ◽  
Plastic Materials ◽  
Wide Range ◽  
Pile Up ◽  
Elastic Plastic Materials

Young’s modulus and hardness data obtained from nanoindentation are commonly affected by phenomena like pile up or sink in, when elastic-plastic materials are tested. In this work, a finite element model was used to evaluate the pile up effect on the determination of mechanical properties from spherical indentation in a wide range of elastic-plastic materials. A new procedure, based on a combination of results obtained from tests performed at multiple maximum loads, is suggested.

A review of the determination of energy release rates for strips in tension and bending. Part I – static solutions

1993 ◽  
Vol 28 (4) ◽  
pp. 237-246 ◽  
Author(s):  
J G Williams
Keyword(s):  
Energy Release ◽  
Release Rates ◽  
Elastic Plastic ◽  
Plastic Materials ◽  
Wide Range ◽  
Static Solutions ◽  
Energy Release Rates ◽  
Elastic Plastic Materials ◽  
Peel Tests

It is shown that solutions for the energy release rate G may be obtained for a uniform strip by simply considering the change in length. The simplicity of the system enables a wide range of boundary conditions and material properties to be incorporated into the analysis and G may be computed for elastic and elastic-plastic materials. Inextensible flexible strips are considered first as they are useful for modelling peel tests and these results are developed to cover elastic and elastic-plastic behaviour. Elastic strips in tension are also considered and the analysis is developed to include transverse loading which induces bending. General considerations of path and loading history dependence are also included.

P-h Curves and Hardness Value Prediction for Spherical Indentation Based on the Representative Stress Approach

2014 ◽  
Vol 493 ◽  
pp. 628-633 ◽  
Author(s):  
I. Nyoman Budiarsa ◽  
Mikdam Jamal
Keyword(s):  
Experimental Data ◽  
Direct Analysis ◽  
Model Material ◽  
Spherical Indentation ◽  
Fe Model ◽  
Fe Modelling ◽  
Plastic Materials ◽  
Wide Range ◽  
Elastic Plastic Materials ◽  
Hardness Values

In this work, finite element (FE) model of spherical indentation has been developed and validated. The relationships between constitutive materials parameters (σy and n) of elastic-plastic materials, indentation P-h curves and hardness on spherical indenters has been systematically investigated by combining representative stress analysis and FE modelling using steel as a typical model material group. Parametric FE models of spherical indentation have been developed. Two new approaches to characterise the P-h curves of spherical indentation have been developed and evaluated. Both approaches were proven to be adequate and effective in predicting indentation P-h curves. The concept and methodology developed is to be used to predict Rockwell hardness value of materials through direct analysis and validated with experimental data on selected sample of steels. The Hardness predicted are compared with the experimental data and showed a good agreement. The approaches established was successfully used to produce hardness values of a wide range of material properties, which is then used to establish the relationship between the hardness values with representative stress.

Relationship between Indenter Calibration and Measured Mechanical Properties of Elastic-Plastic Materials

2015 ◽  
Vol 662 ◽  
pp. 27-30 ◽  
Author(s):  
Jaroslav Čech ◽  
Petr Haušild ◽  
Jiri Nohava
Keyword(s):  
Young’S Modulus ◽  
Young's Modulus ◽  
Plastic Behavior ◽  
Calibration Function ◽  
Simple Method ◽  
Area Function ◽  
Elastic Plastic ◽  
Plastic Materials ◽  
Pile Up ◽  
Elastic Plastic Materials

Calibration of Berkovich indenter area function was performed on materials with different elastic-plastic behavior resulting in pile-up and sink-in, respectively. Experimentally obtained results were compared with the results obtained by the application of theoretical area function. The values of Young’s modulus and hardness were significantly affected by the calibration function used. Since the effects of pile-up and sink-in are already included in the used area function, this simple method can lead to more accurate results of Young’s modulus and hardness measurements.

scholarly journals Finite Element Studies of the Influence of Pile-up on the Analysis of Nanoindentation Data

1996 ◽  
Vol 436 ◽  
Author(s):  
A. Bolshakov ◽  
W. C. Oliver ◽  
G. M. Pharr
Keyword(s):  
Finite Element ◽  
Contact Area ◽  
Peak Load ◽  
Soft Materials ◽  
Modulus Ratio ◽  
Hard Materials ◽  
Plastic Materials ◽  
Wide Range ◽  
Pile Up ◽  
Elastic Plastic Materials

AbstractMethods currently used for analyzing nanoindentation load-displacement data give good predictions of the contact area in the case of hard materials, but can underestimate the contact area by as much as 40% for soft materials which do not work harden. This underestimation results from the pile-up which forms around the hardness impression and leads to potentially significant errors in the measurement of hardness and elastic modulus. Finite element simulations of conical indentation for a wide range of elastic-plastic materials are presented which define the conditions under which pile-up is significant and determine the magnitude of the errors in hardness and modulus which may occur if pile-up is ignored. It is shown that the materials in which pile-up is not an important factor can be experimentally identified from the ratio of the final depth after unloading to the depth of the indentation at peak load, a parameter which also correlates with the hardness-to-modulus ratio.

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