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.

Determination of the elastic properties of glasses and polymers exploiting the resonant characteristic of depth-sensing indentation tests

2001 ◽  
Vol 16 (6) ◽  
pp. 1776-1783 ◽  
Author(s):  
D. Lorenz ◽  
W. Fränzel ◽  
M. Einax ◽  
P. Grau ◽  
G. Berg
Keyword(s):  
Young’S Modulus ◽  
Closed Loop ◽  
Young's Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
Material Behavior ◽  
New Method ◽  
Depth Sensing ◽  
Constant Frequency ◽  
Indentation Tests

Depth-sensing indentation tests can be used to estimate the Young's modulus, hardness, and other characteristics of material behavior. For many materials, the unloading segment of the load–depth curve contains only elastic recovery while the loading segment can contain elastic and plastic deformation. In this paper a new method is presented to determine the Young's modulus of a material from the loading segment of an indentation test. A depth-sensitive hardness tester was used with a load cell integrated into the closed-loop system. Defined mechanical oscillations with constant frequency were generated by adding a piezoelectric stack to the closed loop of the hardness measurement system. Thus the resonance response of the system was obtained, which includes information regarding the stiffness of the tested material. This new method was tested on two polymers and two glasses, an optical and a conventional one. The results obtained for the Young's modulus were in good agreement with other accepted methods.

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.

A New Method Developed for Brittle and Ductile Materials to Evaluate Mechanical Properties of a Lump Specimen in the Use of Indentation Test

2006 ◽  
Vol 129 (2) ◽  
pp. 284-292 ◽  
Author(s):  
Pal Jen Wei ◽  
Jen Fin Lin
Keyword(s):  
Yield Strength ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Elastic Recovery ◽  
Indentation Test ◽  
New Method ◽  
Ductile Materials ◽  
Conventional Material ◽  
Loading And Unloading ◽  
Logarithm Function

In this study, the load-depth (P‐h) relationships matching the experimental results of the nanoindentation tests exhibited at the subregions of small and large depths are obtained, respectively. The relationships associated with these two subregions are then linked by the hyperbolic logarithm function to attain a single expression that is applied in the evaluation of the specimen’s elastic recovery ability, as shown in the unloading process. A new method is developed in the present study to evaluate both Young’s modulus and the yield strength of either a ductile or brittle material through the uses of the appropriate P‐h relationships developed in the load and unloading processes. The results of the Young’s modulus and the yield strength achieved by the present method are compared to those obtained from the conventional material tests for a lump material. The scattering of the experimental data shown in the loading and unloading processes are also interpreted by different causes.

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.

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.

A new method for analyzing data from continuous depth-sensing microindentation tests

1990 ◽  
Vol 5 (1) ◽  
pp. 123-126 ◽  
Author(s):  
D. L. Joslin ◽  
W. C. Oliver
Keyword(s):  
Surface Roughness ◽  
Elastic Modulus ◽  
Cross Sectional Area ◽  
New Method ◽  
Sectional Area ◽  
Depth Sensing ◽  
Cross Sectional ◽  
The Cross ◽  
Effect Of Surface

A new parameter, hardness/modulus2 (H/E2), has been derived from the equations used to calculate the hardness and elastic modulus from data taken during continuous depth-sensing microindentation tests. This paper discusses the use of this parameter to treat the data obtained from a sample whose surface roughness was of the same scale as the size of the indents. The resulting data were widely scattered. This scatter was reduced when the data were plotted in terms of H/E2 versus stiffness. The effect of surface roughness on the hardness and elastic modulus results is removed via stiffness measurements, provided single contacts are made between the indenter and the specimen. The function relating the cross-sectional area of the indenter versus the distance from its point is not required for calculation of H/E2, but the hardness and modulus cannot be determined separately. The parameter H/E2 indicates resistance to plastic penetration in this case.

Elastic recovery and reloading of hardness impressions with a conical indenter

2002 ◽  
Vol 750 ◽  
Author(s):  
A. C. Fischer-Cripps
Keyword(s):  
Residual Stress ◽  
Test Data ◽  
Elastic Recovery ◽  
Indentation Test ◽  
Nanoindentation Test ◽  
Instrumented Indentation ◽  
Specimen Material ◽  
Elastic Event ◽  
Instrumented Indentation Test ◽  
Elastic Unloading

ABSTRACTThe present work is concerned with the analysis of elastic unloading data in conventional methods of analysis of nanoindentation test data. Experimental and finite element results are used to show that the reloading of a residual impression with and without the presence of residual stress is an elastic event, and further shows that the estimation of modulus and hardness computed using established techniques is in error due to the assumption the sides of the residual impression are straight. This work calls into question the validity of commonly used methods of test and analysis of instrumented indentation test data that use the elastic unloading data as the basis for the calculation of modulus and hardness of the specimen material.

Contact Problems at Nano/Microscale and Depth Sensing Indentation Techniques

2010 ◽  
Vol 662 ◽  
pp. 53-76 ◽  
Author(s):  
Feodor M. Borodich
Keyword(s):  
Elastic Modulus ◽  
Direct Method ◽  
Contact Problems ◽  
Work Of Adhesion ◽  
Depth Sensing ◽  
Plastic Properties ◽  
Type Contact ◽  
Indentation Tests ◽  
Properties Of Materials

An overview of development of indentation techniques and connections between contact mechanics and methods of extracting mechanical characteristics from indentation data is given. Observed disagreements between the experimental observations and the models of indentation are discussed. It is shown that this disagreement is often caused by violation of hypotheses that are used in the formulation of the appropriate boundary-value contact problems and strictly speaking one cannot apply directly the solutions of Hertz type contact problems to indentation tests employing the sharp indenters. It is shown that commonly used experimental test involving sharp pyramidal and conical indenters may be applied to study plastic properties of materials while this approach is not very accurate for estimations of elastic modulus of the test solid. The recently proposed by Borodich and Galanov non-direct method that employs data of elastically loading of a spherical indenter is described. It is argued that the non-direct method can be used for determination of both the work of adhesion and elastic modulus of the tested material.

Characterization of HVOF Sprayed Al2O3 - CeO2 Coatings Deposited on Mg Az 91 Alloy

2022 ◽  
Vol 1048 ◽  
pp. 254-260
Author(s):  
Kaushik V. Prasad ◽  
H. Adarsha
Keyword(s):  
Bearing Capacity ◽  
Elastic Recovery ◽  
Indentation Test ◽  
Maximum Load ◽  
Grain Structure ◽  
Az91 Alloy ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Nano Indentation ◽  
Indentation Tests

Al2O3, Al2O3-10%CeO2 and Al2O3 – 20% CeO2 coatings were deposited on Mg AZ91 alloy by High Velocity Oxy Fuel (HVOF) process. The microstructure of deposited coatings was characterized by scanning electron microscopy and x-ray diffraction. Nano-indentation tests were performed on deposited coatings to determine its load bearing capacity and elastic recovery. Al2O3 coatings exhibited coarse grain structure with porous sites. While addition of CeO2 promoted grain refinement in the coatings. A load of 100mN was applied on all the samples for nano-indentation test. Coating with 20%CeO2 exhibited maximum load bearing capacity of 98.7mN with elastic recovery displacement of 1000 nm.

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