Indian Institute of Technology Palakkad&nbsp;(IIT Palakkad or IIT PKD) is a public autonomous&nbsp;engineering&nbsp;and&nbsp;research&nbsp;institute located in&nbsp;Palakkad,&nbsp;Kerala. It was&nbsp;one of the five new&nbsp;IITs&nbsp;proposed in the&nbsp;2014 Union budget of India. The campus was inaugurated on 3 August 2015. The institute has 94 faculty, 978 students, and 63 non-teaching staffs.

IT Palakkad currently offers four-year Bachelor of Technology (B.Tech) and two years MS programmes in 8 different engineering disciplines including&nbsp;Computer Science, Electrical, Mechanical, Civil among others.

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IIT Palakkad

Engineering components can be subjected to normal and/or rotational fretting wear with contacts that are intermittently exposed to the atmosphere. Exposure to the environment may lead to the alteration at the contact due to the changing role of third body particles such as hard oxides which can result in abrasion. The abrasion due to hard oxide particles differs for the closed contact and intermittently opened contact. In the former scenario, the oxides are compacted into tribo-film, while in the latter case they remain loose, leading to bigger role of abrasion. Standard fretting test setup employed to estimate the fretting wear characteristic operates with a constant load such that the contact remains closed between the counter surfaces and does not simulate the opening and closing of the contacts as observed in certain applications. The forceful interruptions to the experiments to simulate open and close condition of the contact require considerable amount of time and effort. In this paper, an accelerated test procedure is proposed and investigated to capture the effect of intermittent opening of the contact without stopping the experiments. A test rig is designed to simulate the opening and closing conditions, and tests were performed with abrasive diamond-like particles. Friction and wear results are compared with those of intermittently contact opening conditions along with operating wear mechanisms. Scanning electron microscope analysis showed that the wear mechanism observed in the case of fretting with intermittent opening of contact is similar to that of fretting with diamond-like abrasives at the contact. © 2017, Springer Science+Business Media, LLC.

World University root node

Department of Mechanical Engineering

Tribology Letters

Accelerated Fretting Wear Tests for Contacts Exposed to Atmosphere

Many numerical models are proposed in the literature using finite element and finite discrete element methods to study fretting wear, barely including the effect of wear debris. These models being computationally expensive, simulating large number of fretting wear cycles is not practically feasible. A new methodology is proposed which needs only bulk material properties like friction/wear coefficients and uses semi-analytical methods to simulate fretting wear with entrapped debris. In this approach, debris are assumed to be attached to one of the surfaces during the fretting process. The results obtained from this approach were compared with fretting experiments. The proposed method permits to capture the wear depth and scar width, and results are very close to that observed in the experiments. © 2016 Elsevier Ltd

Tribology International

Semi analytical fretting wear simulation including wear debris

Generally the fatigue life of the components can be improved by introducing compressive residual stresses up to certain depth from the surface. Laser shock processing (LSP) is one of the surface treatment processes to improve fatigue life of the components. When a short duration laser pulse with high power density (more than 1 GW/cm2) irradiates target surface coated with sacrificial layer in a confined medium generally, shock waves are produced. These shock waves deform the target surface plastically and strengthen the material surface up to certain depth to induce residual stresses. LSP improves many properties of the target material such as fatigue life, wear and corrosion resistance, hardness, and etc. This paper reviews the physics involved at all stages of the process generation of plasma at confined medium-material interface and laser induced shock waves, and generation of residual stresses. Also, the effect of various input parameters such as laser parameters, sacrificial layer material, sacrificial layer material thickness, and etc. on residual stress and hardness is discussed. Finally, the applications and challenges of the LSP are also discussed. © 2017 Elsevier Ltd. All rights reserved.

Materials Today: Proceedings

Laser Shock Processing: Process Physics, Parameters, and Applications

Sugarcane has emerged as the second largest source of biofuel, primarily as ethanol produced in Brazil. Dual row planting using asymmetric spacing of rows can decrease damage to plants and soil structure from harvest equipment though potentially can cause some loss of productivity due to increased shading. Can we assess this loss, without experimental testing of the thousands of potential permutations of planting design and cultivar canopy form? Here we develop a computational framework which couples 3D canopy architectural information, a ray-tracing algorithm, and a steady-state C4 photosynthesis model to study this question. We demonstrate the utility of the model by comparing evenly spaced rows at 100 cm to alternating row spacing of 45 and 155 cm. Asymmetric planting caused a 9% decrease in predicted net canopy carbon uptake over the growing season for a major current cultivar. The loss was greater at lower leaf area indices, when leaves were more vertical and when rows were oriented east-west, suggesting agronomic approaches to minimize loss. This study demonstrates the utility of this computational framework, which could also be used to aid breeding by identifying ideotypes for different environments and objectives, and to assess impacts of environmental change. © 2017, The Author(s).

Environmental Sciences and Sustainable Engineering Centre (ESSENCE)

Fulltext

Bioenergy Research

Development of a Three-Dimensional Ray-Tracing Model of Sugarcane Canopy Photosynthesis and Its Application in Assessing Impacts of Varied Row Spacing

Reduction of CO 2 emissions will require a transition from fossil fuels to alternative energy sources. Expansion of Brazilian sugarcane ethanol provides one near-term scalable solution to reduce CO 2 emissions from the global transport sector. In contrast to corn ethanol, the Brazilian sugarcane ethanol system may offset 86% of CO 2 emissions compared to oil use, and emissions resulting from land-use change to sugarcane are paid back in just 2-8 years. But, it has been uncertain how much further expansion is possible given increasing demand for food and animal feed, climate change impacts and protection of natural ecosystems. We show that Brazilian sugarcane ethanol can provide the equivalent of 3.63-12.77 Mb d -1 of crude oil by 2045 under projected climate change while protecting forests under conservation and accounting for future land demand for food and animal feed production. The corresponding range of CO 2 offsets is 0.55-2.0 Gigatons yr -1. This would displace 3.8-13.7% of crude oil consumption and 1.5-5.6% of net CO 2 emission globally relative to data for 2014.

Nature Climate Change

Brazilian sugarcane ethanol as an expandable green alternative to crude oil use

We present an overview of the statistical properties of turbulence in two-dimensional (2D) fluids. After a brief recapitulation of well-known results for statistically homogeneous and isotropic 2D fluid turbulence, we give an overview of recent progress in this field for such 2D turbulence in conducting fluids, fluids with polymer additives, binary-fluid mixtures, and superfluids; we also discuss the statistical properties of particles advected by 2D turbulent fluids.

Department of Physics

Physics of Fluids

An overview of the statistical properties of two-dimensional turbulence in fluids with particles, conducting fluids, fluids with polymer additives, binary-fluid mixtures, and superfluids

To avoid clearance by the spleen, red blood cells infected with the human malaria parasite Plasmodium falciparum (iRBCs) adhere to the vascular endothelium through adhesive protrusions called “knobs” that the parasite induces on the surface of the host cell. However, the detailed relation between the developing knob structure and the resulting movement in shear flow is not known. Using flow chamber experiments on endothelial monolayers and tracking of the parasite inside the infected host cell, we find that trophozoites (intermediate-stage iRBCs) tend to flip due to their biconcave shape, whereas schizonts (late-stage iRBCs) tend to roll due to their almost spherical shape. We then use adhesive dynamics simulations for spherical cells to predict the effects of knob density and receptor multiplicity per knob on rolling adhesion of schizonts. We find that rolling adhesion requires a homogeneous coverage of the cell surface by knobs and that rolling adhesion becomes more stable and slower for higher knob density. Our experimental data suggest that schizonts are at the border between transient and stable rolling adhesion. They also allow us to establish an estimate for the molecular parameters for schizont adhesion to the vascular endothelium and to predict bond dynamics in the contact region. © 2017 Biophysical Society

Biophysical Journal

Rolling Adhesion of Schizont Stage Malaria-Infected Red Blood Cells in Shear Flow

Gasketed flange joints are widely used in pressure vessels and piping systems. They are subjected to bending load due to differential thermal expansion, wind load, self-weight, etc., in addition to assembly and internal fluid load. Most of the flange designs are based on equivalent pressure method to include the effect of external bending loads. The behavior of gasketed flange joint is complex due to the nonlinear hysteretic behavior of gasket material and contact interfaces between joint members. It becomes more complex when the joint is subjected to bending load at elevated temperatures. In the present work, performance of a flange joint has been studied under internal pressure and external bending load at elevated temperatures. A 3D finite element model is developed, considering the nonlinearities in the joint due to gasket material and contact between its members along with their temperature-dependent material properties. The performance of joint under different bolt preloads, internal fluid pressures, and temperatures is studied. Flange joint with two gaskets (twin-gasketed flange joint, TGJ) placed concentric is also analyzed. The results from finite element analysis (FEA) are validated using four-point bending test on gasketed flange joint. The sealing and strength criteria are considered to determine the maximum allowable bending moment at different internal fluid temperatures, for both single- and twin-gasketed flange joints with spiral wound gasket. Twin gasket is able to withstand higher bending moment without leakage compared to single gasket. Results show that the allowable load on flange joint depends on operating temperature and gasket configuration. Copyright © 2017 by ASME.

Journal of Pressure Vessel Technology, Transactions of the ASME

A Study on the Behavior of Single- and Twin-Gasketed Flange Joint under External Bending Load

In this article, a generic framework, which takes into account of both the centrifugal and thermal effects, is introduced towards rotordynamic characterization of rotating labyrinth gas turbine seals. A well-established labyrinth seal clearance-leakage model, based on a combined three-dimensional computational fluid dynamics and finite element methodology, along with a second-order rotordynamics model is engaged. The influence of combined centrifugal and thermal radial growth on the rotordynamic characteristics of a generic rotating labyrinth gas turbine seal is explored. For a given rotational speed, the computed rotordynamic seal forces and coefficients, including the stability parameters are compared with the one without considering thermal growth (ambient condition), as a function of pressure ratio and temperature. The results show a significant variation of the crucial seal coefficients with the inclusion of thermal growth and the influence largely varies with both temperature and pressure ratio. Of particular interest is the onset of instability detected at an elevated temperature, regardless of pressure ratio, which necessitates the inclusion of thermal growth so as to avoid early rotor/seal failures. The inherent flow field investigation corroborates well with the rotordynamic characteristics of the seal and its combined centrifugal and thermal effects. © 2017 Elsevier Ltd

International Journal of Mechanical Sciences

Rotordynamic characterization of rotating labyrinth gas turbine seals with radial growth: Combined centrifugal and thermal effects

Owing to increase in the demand for power, a number of power plants have been installed in the recent past. One of the vital components in these plants is gasketed flange joint. The behaviour of gasketed flange joint is highly dependent on the deformation characteristics of gasket material. In the present study, the deformation characteristic of spiral wound gasket along thickness direction is determined experimentally for different loading rates. Gasket has high nonlinearity under both loading and unloading, with hysteresis. Based on its characteristics, the flange joint is analysed to study its performance and leakage behaviour under static condition. 3D finite element model of flange joint is developed by considering the gasket as interface entity. Finite element analysis of flange joint is performed by including the nonlinear hysteretic behaviour of gasket, under different loading rate and frictional contact between joint members. The influence of different loading and unloading rates is emphasized on the sealing performance of flange joint using leakage pressure. The gasket deforms more when loaded at low rate. This phenomenon also affects the ability to withstand internal fluid without leakage. The maximum safe pressure without leakage increases, when gasket is loaded and unloaded at low rate. © Springer Nature Singapore Pte Ltd. 2017.