Energy principle of indentation contact: The application to sapphire

1993 ◽  
Vol 8 (5) ◽  
pp. 1068-1078 ◽  
Author(s):  
Roman Nowak ◽  
Mototsugu Sakai
Keyword(s):  
Indentation Test ◽  
Shear Stresses ◽  
Anisotropic Behavior ◽  
Energy Principle ◽  
Triangular Pyramid ◽  
Indentation Tests ◽  
Crystallographic Planes ◽  
Continuous Indentation ◽  
True Hardness ◽  
Crystallographic Orientations

The recently developed energy principle of indentation mechanics was applied to the continuous indentation test performed on pure sapphire. Three crystallographic planes, M = (10$\overline 1$0), A = (1$\overline 1$10), and C = (0001), have been indented by a symmetrical triangular pyramid (Berkovich). The distinct anisotropic behavior of the indented crystal has been observed for the maximum indentation loads of 1.961 N, 0.686 N, and 0.392 N. The indentation hysteresis loop energy and the related “true hardness parameter” have been determined for various crystallographic orientations, as well as for two different orientations of the indenter. The observed effects have been discussed in terms of the energy principle of indentation with crystallographic considerations. The effective resolved shear stresses for the slip and twinning systems were calculated and applied to the anisotropic indentation behavior. It was concluded that the energy principle is highly recommended for analyzing the data of continuous indentation tests.

Statistical Analysis of Experimental Parameters in Continuous Indentation Tests Using Taguchi Method

2003 ◽  
Vol 125 (4) ◽  
pp. 406-411 ◽  
Author(s):  
Eun-chae Jeon ◽  
Joo-Seung Park ◽  
Dongil Kwon
Keyword(s):  
Taguchi Method ◽  
Tensile Properties ◽  
Indentation Depth ◽  
Signal To Noise Ratio ◽  
Indentation Test ◽  
Indentation Load ◽  
Optimum Parameters ◽  
Experimental Parameters ◽  
Indentation Tests ◽  
Continuous Indentation

The continuous indentation test, which applies an indentation load to a material and records the indentation depth, yields indentation tensile properties whose accuracy can vary depending on such experimental parameters as number of unloadings, unloading ratio, maximum depth ratio and indenter radius. The Taguchi method was used to quantify their effects and to determine their optimum values. Using signal-to-noise ratio calculated from the error in the indentation tensile properties, the criterions and the optimum values for the experimental parameters were presented. The indentation tensile properties evaluated with the optimum parameters were in better agreement with the tensile properties.

Identification of Hardening Parameters of Metals From Spherical Indentation Tests

2001 ◽  
Vol 123 (3) ◽  
pp. 245-250 ◽  
Author(s):  
S. Kucharski ◽  
Z. Mro´z
Keyword(s):  
Indentation Test ◽  
Strain Curve ◽  
Load Level ◽  
Spherical Indentation ◽  
Indentation Tests ◽  
Geometric Sequence ◽  
Loading And Unloading ◽  
Plastic Hardening ◽  
Hardening Curve ◽  
Two Parameters

The identification method of hardening parameters specifying stress-strain curve is proposed by applying spherical indentation test and measuring the penetration depth during loading and unloading. The loading program is composed of a geometric sequence of loading and partial unloading steps from which the variation of permanent penetration with load level is determined. This data is used for specification of two parameters k and m occurring in the plastic hardening curve εp=σ/k1/m, where εp denotes the plastic strain.

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.

ELASTO-PLASTIC PROPERTIES OF Mo-MODIFIED Ti DEDUCED FROM INDENTATION TESTS AND FINITE ELEMENT ANALYSIS

2019 ◽  
Vol 26 (07) ◽  
pp. 1850225
Author(s):  
YONG MA ◽  
ZHAO YANG ◽  
SHENGWANG YU ◽  
BING ZHOU ◽  
HONGJUN HEI ◽  
...  
Keyword(s):  
Finite Element ◽  
Surface Treatment ◽  
Load Capacity ◽  
Indentation Test ◽  
Element Analysis ◽  
Plastic Properties ◽  
Polynomial Expression ◽  
Indentation Tests ◽  
Graded Material ◽  
Micro Indentation

The aim of this paper is to establish an approach to quantitatively determine the elasto-plastic parameters of the Mo-modified Ti obtained by the plasma surface alloying technique. A micro-indentation test is conducted on the surface under 10[Formula: see text]N. Considering size effects, nanoindentation tests are conducted on the cross-section with two loads of 6 and 8[Formula: see text]mN. Assuming nanoindentation testing sublayers are homogeneous, finite element reverse analysis is adopted to determine their plastic parameters. According to the gradient distributions of the elasto-plastic parameters with depth in the Mo-modified Ti, two types of mathematical expressions are proposed. Compared with the polynomial expression, the linear simplified expression does not need the graded material to be sectioned and has practical utility in the surface treatment industry. The validation of the linear simplified expression is verified by the micro-indentation test and corresponding finite element forward analysis. This approach can assist in improving the surface treatment process of the Mo-modified Ti and further enhancing its load capacity and wear resistance.

A continuous indentation test for metals

1986 ◽  
Vol 34 (2) ◽  
pp. 313-324 ◽  
Author(s):  
D.V. Jaramillo ◽  
S. Kuriyama ◽  
M.A. Meyers
Keyword(s):  
Indentation Test ◽  
Continuous Indentation

Indentation Tests Based on Gelatin Phantom

2013 ◽  
Vol 483 ◽  
pp. 386-390
Author(s):  
Lei Song ◽  
Tong Su ◽  
Li Ying Gao ◽  
Qin He Zhang
Keyword(s):  
Constitutive Model ◽  
Least Squares Method ◽  
Fem Simulation ◽  
Indentation Test ◽  
Target Material ◽  
Fem Analysis ◽  
Material Model ◽  
Fem Model ◽  
Indentation Tests ◽  
Viscoelastic Characteristics

In order to improve the accuracy of biopsy, an accurate FEM model is quite essential. To get the coefficients of the puncture target material which will be used in the Abaqus FEM analysis, the paper performed indentation test on gelatin phantom which is more stable than normal biological tissue. The Neo-Hookean and the improved Kelvin constitutive model were used to describe the mechanical properties of gelatin phantom demonstrated in the tests, including the hyperelastic and viscoelastic characteristics, then least squares method was used to fit the experimental data, finally the parameters of each constitutive model were achieved, which will be used to establish the material model in the further Abaqus FEM simulation.

Improved Techniques for Measuring the Indentation and Thickness of Articular Cartilage

1989 ◽  
Vol 203 (3) ◽  
pp. 143-150 ◽  
Author(s):  
A C Swann ◽  
B B Seedhom
Keyword(s):  
Articular Cartilage ◽  
High Speed ◽  
Articular Surface ◽  
Indentation Test ◽  
Displacement Transducer ◽  
Data Logging ◽  
Large Numbers ◽  
Indentation Tests ◽  
The Moment ◽  
Measurement Repeatability

A review of the techniques previously employed in the indentation and measurement of the thickness of articular cartilage has led to new and improved techniques for performing both measurements. By utilizing high-speed, microcomputer-controlled data logging techniques, simultaneous monitoring of signals from a dynamic load cell and a displacement transducer could be made throughout an indentation test. The position of the indenter as it touched the articular surface could thus be determined automatically by identifying the moment at which a positive change in the load signal occurred. Less accurate and more time consuming techniques previously required for determining the position of the cartilage surface were hence avoided. The apparatus also included a critically damped dashpot which prevented any transient loads being applied to the cartilage. Depths of indentation could be measured to an accuracy of 0.005 mm with a measurement repeatability of 2.14 per cent. By replacing the indenter with a sharp needle, the apparatus was also capable of measuring the undeformed thickness of cartilage. An accuracy of ±0.012 mm could be achieved with a measurement repeatability of 1.2 per cent. The apparatus is particularly suited to survey work where large numbers of indentation tests are to be performed.

Determination of High-Temperature Creep Property of High-Cr Steel Based Upon Indentation Test

2015 ◽  
Author(s):  
Masayuki Arai ◽  
Takahiro Ishikawa ◽  
Yukio Takahashi ◽  
Tomohisa Kumagai
Keyword(s):  
High Temperature ◽  
Creep Property ◽  
Indentation Test ◽  
Indentation Load ◽  
High Temperature Creep ◽  
Element Analysis ◽  
Temperature Creep ◽  
Inner Pressure ◽  
Indentation Tests ◽  
Actual Response

In this paper, the procedure which can estimate creep exponent and coefficient in Norton’s law from the impression size rather than the penetration depth is discussed based upon a high-temperature creep indentation test. Firstly, an analytical solution related to the change in impression size with dwelling time at an indentation load is formulated by solving problem of infinite creeping media embedding spherical cavity subjected to an inner pressure which characterizes an indentation load. The applicability of the formula to elastic-plastic-creeping model resembling an actual response is checked by conducting non-linear finite-element analysis combined with contact option. Finally, creep indentation tests are conducted for a high-Cr ferritic heat-resisting steel. It is shown that the creep parameters at a lower stress level can be estimated at temperature 873K.

scholarly journals Revelation of a functional dependence of the sum of two uniaxial strengths/hardness on elastic work/total work of indentation

2006 ◽  
Vol 21 (4) ◽  
pp. 895-903 ◽  
Author(s):  
Dejun Ma ◽  
Taihua Zhang ◽  
Chung Wo Ong
Keyword(s):  
Functional Relationship ◽  
Functional Dependence ◽  
Indentation Test ◽  
Fatigue Tests ◽  
Total Work ◽  
Finite Element Analyses ◽  
Instrumented Indentation ◽  
The Relationship ◽  
True Hardness ◽  
Instrumented Indentation Test

Dimensional and finite element analyses were used to analyze the relationship between the mechanical properties and instrumented indentation response of materials. Results revealed the existence of a functional dependence of (engineering yield strength σE,y + engineering tensile strength σE,b)/Oliver & Pharr hardness on the ratio of reversible elastic work to total work obtained from an indentation test. The relationship links up the Oliver & Pharr hardness with the material strengths, although the Oliver & Pharr hardness may deviate from the true hardness when sinking in or piling up occurs. The functional relationship can further be used to estimate the sum σE,y + σE,b according to the data of an instrumented indentation test. The σE,y + σE,b value better reflects the strength of a material compared to the hardness value alone. The method was shown to be effective when applied to aluminum alloys. The relationship can further be used to estimate the fatigue limits, which are usually obtained from macroscopic fatigue tests in different modes.

The Determination of Stress-Strain Curves of Thin Layers Using Indentation Tests

1986 ◽  
Vol 108 (3) ◽  
pp. 230-232 ◽  
Author(s):  
A. G. Tangena ◽  
G. A. M. Hurkx
Keyword(s):  
Finite Element ◽  
Indentation Test ◽  
Thin Layers ◽  
Finite Element Calculation ◽  
Element Calculation ◽  
Plastic Part ◽  
Stress Strain ◽  
Metal Coatings ◽  
Indentation Tests

A method is presented for estimating the plastic part of stress-strain curves of metal coatings, using a Brinell indentation test. The accuracy of the stress-strain curves obtained in this way is tested by using these curves in a finite element calculation and comparing the calculated results with results from experiments. Stress-strain curves are given for galvanic layers such as citrate Au, Co-Au, sulfamate Ni and also for solid annealed pure Au.

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