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Pankaj Dhaka

Bio: Pankaj Dhaka is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Fretting & Test method. The author has an hindex of 2, co-authored 6 publications receiving 6 citations. Previous affiliations of Pankaj Dhaka include National Institute of Technology, Hamirpur.

Papers
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Journal ArticleDOI
TL;DR: In this article, the authors present the current understanding relating to fatigue response of materials that are small in volume and tested through cyclic automated ball indentation and cyclic small punch test methods.

4 citations

Journal ArticleDOI
08 Mar 2019
TL;DR: In this paper, a 2-D elastic and elasto-plastic finite element analysis has been carried out for a rounded contact geometry to study the influence of the radius of the corners "R" and length of the flat region "2a".
Abstract: The blade-disc dovetail interface in an aero-engine compressor is characterized by a non-uniform pressure distribution which can be obtained by an equivalent flat with round edge-on-plate configuration. The contact tractions for a mating pair are affected by many parameters which include, contact geometry, loading conditions, and material properties; with contact geometry being one of the prominent factors. In the present work, a 2-D elastic and elasto-plastic finite element analysis has been carried out for a rounded contact geometry to study the influence of the radius of the corners ‘R’ and length of the flat region ‘2a’. It is observed that the peak tensile stress in the fretting direction was found to decrease with increasing ‘a’ (for constant ‘R’) which is likely to delay the crack initiation. Also, as compared to elasto-plastic analysis, elastic analysis overestimates peak tensile stress and possibly give a conservative estimate for the fretting fatigue life. Further, the effect of modelling elastic-plastic behaviour is significant for low a/R ratio (for constant ‘R’). However, opposite trend was observed when ‘R’ was varied keeping ‘a’ constant. Also, it is found that the effect of contact geometry cannot be characterized using a single parameter like a/R ratio or contact area.

4 citations

Proceedings ArticleDOI
09 Nov 2018
TL;DR: In this article, a Tungsten Carbide (WC) spherical ball indenter of 1.57 mm diameter was used for compression-compression fatigue testing of the specimen under load control at a low frequency of loading (typically 0.1 Hz to 1 Hz).
Abstract: An experimental investigation of the fatigue response of commonly used structural stainless steel — SS 304 L(N) and SS 316 L(N) — and its weld was carried out through automated cyclic ball indentation (ABI). A Tungsten Carbide (WC) spherical ball indenter of 1.57 mm diameter was used for compression-compression fatigue testing of the specimen under load control at a low frequency of loading (typically 0.1 Hz to 1 Hz). The force-displacement response during fatigue loading was logged continuously during fatigue test and the data was analyzed to extract details such as variations in: total depth of penetration, loading and unloading slopes, loading/unloading intercept, displacement range as a function of number of cycles. From the results, one could identify an unsteady response of material during cyclic loading after some cycles of fatigue loading — typical of failure; this input was used to compare the fatigue response of different zones of the weld. Even though the applied frequency of loading is relatively less (∼ 1 Hz), due to the high levels of plastic deformation that is developed during the indentation process, one could expect an effect of strain rate on the fatigue response during cyclic ball indentation. To verify this, experiments were carried out at three distinct frequencies of 0.1 Hz, 0.5 Hz and 1 Hz for a given loading condition. Further, it was observed that the material response in weld region is the best, followed by the base metal. This can be corroborated with the weld microstructure that is obtained as a consequence of processing. Frequency of loading did not have significant influence on the fatigue failure life. Numerical simulation of cyclic ball indentation was carried out to extract some relevant parameters for failure life such as mean stress and local stress ratio. This will serve as input to correlation of failure life data obtained from conventional specimens.

2 citations

Journal ArticleDOI
TL;DR: In this article, the effect of dissimilar materials on fretting behavior was studied by modeling elastic-plastic behavior for combinations of three different materials, namely, SS 304, ASTM A302-B, and aluminum.
Abstract: Fretting is a damaging phenomenon, generally observed when a mating pair is subjected to a small amplitude of oscillatory motion. The contact behavior in fretting is governed by a complex interaction between mechanical properties of mating pair, contact geometry, and loading conditions. In most of the practical applications, dissimilar materials are chosen for a contacting pair with one of the materials having superior material properties than other so as to replace the worn-out or unfit component during the maintenance. In the literature, many researchers have studied the effect of dissimilar materials on fretting behavior but mainly in the context of hardness. As experimental methodology has been adopted in these studies, the effect of dissimilar material properties has been reported in terms of global variables like wear volume or fretting fatigue life, but its influence on underlying local contact tractions could not be studied. In the present work, a two-dimensional finite element analysis has been carried out for a cylinder-on-plate configuration. The effect of dissimilar materials for the mating pair has been studied by modeling elastic–plastic behavior for combinations of three different materials, namely, SS 304, ASTM A302-B, and aluminum. The validation of the finite element model is carried out by comparing the results of elastic analysis with the analytical solutions available in the literature. The pertinent contact parameters in the context of fretting wear, namely, contact pressure, contact slip, and contact stresses are extracted. A frictional dissipation energy density-based approach is used for the qualitative comparison of the fretting damage for different cases and validated with the literature data.

2 citations

Book ChapterDOI
01 Jan 2014
TL;DR: In this paper, a computational study of longitudinal fins of different profiles has been carried out, where various fin profiles have been modeled in CATIA and further simulations were carried out in ANSYS Fluent.
Abstract: In this paper, a computational study of longitudinal fins of different profiles has been carried out. For this purpose, various fin profiles have been modeled in CATIA and the further simulations were carried out in ANSYS Fluent. The present research is focused on the performance parameters of fins such as temperature distribution, fin effectiveness, and fin efficiency for different fin geometries. The values obtained from the CFD software have been compared with the theoretical values to validate the results. Also an attempt has been made to compare the weight and cost associated so as to develop a strong basis for the selection of fins.

Cited by
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01 Jan 2008
TL;DR: In this article, the authors classified the contact conditions at the pad-to-rotor interface as a conformal dry s-drone interface and showed that the contact condition depends strongly on contact conditions.
Abstract: Passenger car disc brakes are safety-critical components whose performance depends strongly on contact conditions at the pad-to-rotor interface. The interface can be classified as a conformal dry s ...

108 citations

Journal ArticleDOI
TL;DR: The Small Punch Test (SPT) was developed for situations where source material is scarce, costly or otherwise difficult to acquire, and has been used for assessing components with variable, location-dependent material properties.
Abstract: The small punch test (SPT) was developed for situations where source material is scarce, costly or otherwise difficult to acquire, and has been used for assessing components with variable, location-dependent material properties. Although lacking standardization, the SPT has been employed to assess material properties and verified using traditional testing. Several methods exist for equating SPT results with traditional stress–strain data. There are, however, areas of weakness, such as fracture and fatigue approaches. This document outlines the history and methodologies of SPT, reviewing the body of contemporary literature and presenting relevant findings and formulations for correlating SPT results with conventional tests. Analysis of literature is extended to evaluating the suitability of the SPT for use with additively manufactured (AM) materials. The suitability of this approach is shown through a parametric study using an approximation of the SPT via FEA, varying material properties as would be seen with varying AM process parameters. Equations describing the relationship between SPT results and conventional testing data are presented. Correlation constants dictating these relationships are determined using an accumulation of data from the literature reviewed here, along with novel experimental data. This includes AM materials to assess the fit of these and provide context for a wider view of the methodology and its interest to materials science and additive manufacturing. A case is made for the continued development of the small punch test, identifying strengths and knowledge gaps, showing need for standardization of this simple yet highly versatile method for expediting studies of material properties and optimization.

13 citations

Journal ArticleDOI
01 Oct 2022-Friction
TL;DR: A recent survey as discussed by the authors highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.
Abstract: Abstract Around 1,000 peer-reviewed papers were selected from 3,450 articles published during 2020–2021, and reviewed as the representative advances in tribology research worldwide. The survey highlights the development in lubrication, wear and surface engineering, biotribology, high temperature tribology, and computational tribology, providing a show window of the achievements of recent fundamental and application researches in the field of tribology.

10 citations

Journal Article
TL;DR: In this article, an elastic-static contact model to solve both the normal contact problem and the tangential contact problem is presented. And the model is validated with analytical solutions for a sphere on flat geometry and a wear law issued from the literature and based on the friction energy is used to simulate surface wear.
Abstract: The paper presents a numerical model to investigate fretting wear either under partial or gross slip conditions. An efficient three-dimensional elastic-static contact model to solve both the normal contact problem and the tangential contact problem is presented. The contact model is validated with analytical solutions for a sphere on flat geometry. A wear law issued from the literature and based on the friction energy is used to simulate surface wear. Numerical friction logs are obtained and the wear rate evolution is found to be highly dependent on the tangential displacement.

9 citations

Journal ArticleDOI
TL;DR: Small specimen mechanical testing is an exciting and rapidly developing field in which fundamental deformation behaviours can be observed from experiments performed on comparatively small amounts of data as discussed by the authors, which can be found in this paper.
Abstract: Small specimen mechanical testing is an exciting and rapidly developing field in which fundamental deformation behaviours can be observed from experiments performed on comparatively small amounts o...

8 citations