The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
A. Kumaraswamy - One of the best experts on this subject based on the ideXlab platform.
-
a numerical approach to investigate the effect of temperature on Constraint Factor of ti alloy under static indentation conditions
Transactions of The Indian Institute of Metals, 2017Co-Authors: Ambuj Saxena, Akshay Rai, A. KumaraswamyAbstract:Temperature dependence of Constraint Factor i.e. the ratio of static indentation hardness to uniaxial flow stress was studied for Ti–6Al–4V from RT to 673 K using FEA. Surface-to-surface contact with finite sliding, which was used to model the interaction between spherical indenter/test specimen and the constitutive equations were then applied in axi-symmetric FE model. The results obtained from numerical analysis were in good agreement with the modified Expanding Cavity Model. Meyer’s hardness increased with average strain and strain hardening index increased from 0.19 to 0.21 with rise in temperature.
-
Effect of temperature on Constraint Factor of IN718 under static indentation conditions
Materials Science and Engineering: A, 2010Co-Authors: A. Kumaraswamy, V. Vasudeva RaoAbstract:Abstract Static indentation and compression tests have been carried out on IN718 in the temperature range of 300–1073 K with a view to evaluate the effect of temperature on Constraint Factor (CF), that is the ratio of indentation hardness to flow stress. The value of CF is found to be below 3 at room temperature and above 3 at elevated temperatures. The experimental results are also compared with Expansion Cavity Model (ECM) and Fully Plastic Model (FPM).
-
effect of temperature on Constraint Factor of ti 6al 4v under static indentation conditions
Scripta Materialia, 2006Co-Authors: A. Kumaraswamy, B. VenkataramanAbstract:Abstract The Constraint Factor (CF), the ratio of indentation hardness to flow stress, was evaluated for Ti–6Al–4V up to 673 K, based on static hardness and uniaxial flow stress. CF is dependent on temperature under elastic–plastic deformation conditions. In the fully plastic regime, the CF was independent of strain and temperature.
-
Effect of temperature on Constraint Factor of Ti–6Al–4V under static indentation conditions
Scripta Materialia, 2006Co-Authors: A. Kumaraswamy, B. VenkataramanAbstract:Abstract The Constraint Factor (CF), the ratio of indentation hardness to flow stress, was evaluated for Ti–6Al–4V up to 673 K, based on static hardness and uniaxial flow stress. CF is dependent on temperature under elastic–plastic deformation conditions. In the fully plastic regime, the CF was independent of strain and temperature.
B. Venkataraman - One of the best experts on this subject based on the ideXlab platform.
-
effect of temperature on Constraint Factor of ti 6al 4v under static indentation conditions
Scripta Materialia, 2006Co-Authors: A. Kumaraswamy, B. VenkataramanAbstract:Abstract The Constraint Factor (CF), the ratio of indentation hardness to flow stress, was evaluated for Ti–6Al–4V up to 673 K, based on static hardness and uniaxial flow stress. CF is dependent on temperature under elastic–plastic deformation conditions. In the fully plastic regime, the CF was independent of strain and temperature.
-
Effect of temperature on Constraint Factor of Ti–6Al–4V under static indentation conditions
Scripta Materialia, 2006Co-Authors: A. Kumaraswamy, B. VenkataramanAbstract:Abstract The Constraint Factor (CF), the ratio of indentation hardness to flow stress, was evaluated for Ti–6Al–4V up to 673 K, based on static hardness and uniaxial flow stress. CF is dependent on temperature under elastic–plastic deformation conditions. In the fully plastic regime, the CF was independent of strain and temperature.
Dongil Kwon - One of the best experts on this subject based on the ideXlab platform.
-
effect of contact angle on contact morphology and vickers hardness measurement in instrumented indentation testing
International Journal of Mechanical Sciences, 2014Co-Authors: Seungkyun Kang, Dongil KwonAbstract:Abstract We derive a general contact-depth function for the Vickers indenter by modifying a scaling relation between yield strain and indentation depth ratio, which is comprised of indenter angle, plastic Constraint Factor, and indentation depth ratio. The validity of this function is demonstrated by using various indenters of different angles. A method for calibrating the actual contact area of an imperfectly shaped Vickers indenter is suggested that yields a better evaluation of Vickers hardness in the instrumented indentation test.
G. Sundararajan - One of the best experts on this subject based on the ideXlab platform.
-
On the Constraint Factor and Tabor Coefficient Pertinent to Spherical Indentation
Transactions of the Indian Institute of Metals, 2018Co-Authors: Bolla Reddy Bodapati, P. Sudharshan Phani, P. P. Bhattacharjee, G. SundararajanAbstract:Measuring the uniaxial stress–strain response from indentation testing has been of great interest to the materials community ever since the seminal work on spherical indentation by David Tabor. In this regard, spherical indentation is the primary choice due to the ability to access a wide range of strains in a single test. While indentation testing is fairly simple to perform, the conversion Factors required to calculate the uniaxial flow stress from hardness, which is commonly referred to as Constraint Factor and uniaxial strain from indentation contact radius and ball radius, which is called the Tabor coefficient, are not necessarily constant and most of the prior work involves assumptions about one of these conversion Factors to calculate the other. In this work, we present a finite element analysis-based approach to independently determine the Constraint Factor and Tabor coefficient in the fully plastic indentation regime which is a pre-requisite for this analysis. The criteria to determine whether fully plastic indentation regime is satisfied has also been presented. The proposed approach has been validated by comparing the uniaxial stress–strain response from spherical indentation tests on OFHC copper and the data obtained by conventional uniaxial testing. Excellent agreement has been found between the two approaches which can be readily applied for measuring the uniaxial stress–strain response of coatings which is otherwise difficult to determine.
-
Understanding dynamic indentation behaviour of metallic materials
Materials Science and Technology, 2012Co-Authors: G. SundararajanAbstract:The static indentation behaviour of metallic materials, especially with a spherical indentor, has been well studied and a procedure for conversion of hardness versus indentation diameter data to flow stress–plastic strain data utilising the concepts of Constraint Factor and representative strain due to Tabor, has been well established on the basis of a large number of experiments and numerical simulations. In contrast, the dynamic indentation (DI) hardness behaviour of metallic materials, characterised by ultrahigh strain rate plastic deformation under adiabatic conditions, is poorly understood. In particular, it is not clear whether the concepts valid for static indentation are equally valid under DI conditions. The above aspects of DI are discussed in light of recent results on DI obtained in the author’s laboratory.
-
On the Constraint Factor associated with the indentation of work-hardening materials with a spherical ball
Metallurgical Transactions A, 1991Co-Authors: Y. Tirupataiah, G. SundararajanAbstract:It is generally accepted that the Constraint Factor (CF) associated with the indentation of metallic materials by a much harder indentor is in the range of 2.8 to 3.0. Invariably, the CF is assumed to have a constant value in the above range irrespective of the material indented while correlating the hardness of the material indented with its uniaxial strength properties. The objective of the present investigation is to assess the above assumption by evaluating the CF associated with the indentation process as a function of strain in the case of metallic materials exhibiting a wide range with respect to elastic modulus, strength, and strain-hardening rate. The results indicate that the CF is not really a constant but is dependent on the various material properties. The experimental CF-strain relationship observed in all of the test materials has been rationalized on the basis of elastic-plastic and fully plastic indentation models. While the theoretical models can explain the trend of the data, they are not capable of making adequately accurate quantitative predictions.
V. Vasudeva Rao - One of the best experts on this subject based on the ideXlab platform.
-
Effect of temperature on Constraint Factor of IN718 under static indentation conditions
Materials Science and Engineering: A, 2010Co-Authors: A. Kumaraswamy, V. Vasudeva RaoAbstract:Abstract Static indentation and compression tests have been carried out on IN718 in the temperature range of 300–1073 K with a view to evaluate the effect of temperature on Constraint Factor (CF), that is the ratio of indentation hardness to flow stress. The value of CF is found to be below 3 at room temperature and above 3 at elevated temperatures. The experimental results are also compared with Expansion Cavity Model (ECM) and Fully Plastic Model (FPM).