Department of Engineering Design

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Femtosecond laser-assisted surface texturing of compression piston rings is proposed and demonstrated. A femtosecond pulsed Ti3+:sapphire laser is used to generate dimples of the same size but with different area density on a moly-chrome ceramic deposited cast iron piston ring. The influence of the surface morphology and tribology operating conditions, such as reciprocating frequency and temperature of the lubricant, on friction and wear characteristics of textured piston rings and plateau honed liner samples is investigated. A decrease in the friction coefficient is observed with the texturing of rings. The dimple area density, which is defined as the ratio of the total textured area and the total area of the surface, of 16% and 27% offered a reduced coefficient of friction and minimize wear on the liner surface. © 2020 Royal Society of Chemistry. All rights reserved.

World University root node

Department Of Physics

Journal of Tribology

Femtosecond Pulsed Ti:Sapphire Laser-Assisted Surface Texturing on Piston Ring and Its Tribology Characterization

Wheel lock in a vehicle during braking is detrimental to its safety, in addition to causing poor braking performance. Wheel slip regulation algorithms could potentially prevent wheel lock and are hence required to be tested and tuned thoroughly prior to in-vehicle deployment. Generally, software-in-the-loop and hardware-in-the-loop tests are explored before on-road vehicle testing. A brake dynamometer can potentially be utilized for wheel slip regulation testing, and this can be placed in between hardware-in-the-loop tests and on-road vehicle testing. Prior to evaluation of wheel slip regulation on a brake dynamometer, it is imperative to realize a wheel lock scenario. This work proposes a methodical framework for emulating wheel lock in a brake dynamometer. In this study, the dynamic effects during braking, particularly load transfer, wheel slip and tyre–road interactions, are subsumed into a single variable termed ‘equivalent inertia’ to replicate a wheel lock event. The variations of this variable were captured through extensive tests on a hardware-in-the-loop platform that consists of a pneumatic brake setup interfaced with IPG TruckMaker® co-simulated with MATLAB/Simulink®, across varying load, road and braking conditions. Equivalent inertia profiles thus generated were then realized in the brake dynamometer, via mechanical discs and electrical inertia. Angular speed profiles from hardware-in-the-loop and dynamometer tests were compared to corroborate the framework. A close correlation between the profiles, highlighted by the root mean square deviation of the order of 100 rad/s, established the effectiveness of the proposed scheme. © IMechE 2020.

Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering

An experimentally corroborated framework for emulating wheel lock in a heavy vehicle brake dynamometer

Electrification of military vehicles offers the potential for extended stealth operation, enhanced vehicle performance, and onboard electric power. This study proposes a hybrid electric powertrain for a military tracked vehicle with hybrid energy storage (battery and capacitor) and multi-speed transmission. Initially, component sizing of the proposed powertrain and a series hybrid electric powertrain was done based on power and torque analysis of vehicle performance requirements on different operating terrains. A rule-based control strategy was then developed for the proposed powertrain to maintain high performance as well as reduce energy losses. The performance of the proposed powertrain and the series configuration was evaluated using AVL Cruise software over synthesized drive cycles that represent the real-world activities of military tracked vehicles. Comparative analysis during component sizing showed that the proposed powertrain provides a reduction in powertrain mass by 389 kg (2.72%). From the performance analysis, it was observed that the fuel economy of the proposed powertrain improved by almost 30.27% as compared to the series configuration while maintaining vehicle performance. © 2021 Elsevier Ltd

Energy

Design and analysis of a hybrid electric powertrain for military tracked vehicles

The present study reports developing a bench-top Laser-Induced Breakdown Spectroscopy (LIBS) set up for the online analysis of powder samples without sample preparation. The powder particle blow-off during pulsed laser ablation was mitigated by adding a blow gas (an inert gas blown across the ablation surface) and a suction unit (for extraction of the blow gas and blown-off particle cloud) to the existing LIBS setup. The influence of a blow-gas combined with a suction unit on LIBS emission intensity from coal powder and flyash particles is studied in the present work. The effect of the blow gas flow rate and the suction pressure was studied on the LI-BS emission intensity and removal of the laser blown-off particle cloud. The combination gas flow at 2 lpm (liter per minute) flow rate and suction at 925 mbar (absolute) show an increase in the LIBS emission intensity and effective particle removal. The ratio of LIBS emission intensity of the powder sample and solid-target (pellet) sample improved from 0.25 without the Ar gas flow and the suction unit to 0.85, which is by a factor of 3.4 times with the proposed approach. © 2021 Elsevier B.V.

Department of Applied Mechanics

Spectrochimica Acta - Part B Atomic Spectroscopy

LIBS technique combined with blow gas and vacuum suction to remove particle cloud and enhance emission intensity during characterization of powder samples

A benchtop laser-induced breakdown spectroscopy is demonstrated to determine the elemental carbon content present in raw coal used for combustion in power plants. The spectral intensities of molecular CN and C2 emission are measured together with the atomic carbon (C) and other inorganic elements (Si, Fe, Mg, Al, Ca, Na, and K) in the laser-induced breakdown spectroscopy spectrum of coal. The emission persistence time of C2 molecule emission is measured from the coal plasma generated by a nanosecond laser ablation with a wavelength of 266 nm in the Ar atmosphere. The emission persistence time of molecular C2 emission along with the spectral intensities of major ash elements (Fe, Si, Al, and Ca) and carbon emissions (atomic C, molecular CN, and C2) shows a better relationship with the carbon wt% of different coal samples. The calibration model to measure elemental carbon (wt%) is developed by combining the spectral characteristics (spectral intensity) and the temporal characteristics (emission persistence time of C2 molecule emission). The temporal characteristic studies combined with the spectroscopic data in the partial least square regression model have resulted in an improvement in the root mean square error of validation, and the relative standard deviation is reduced from 10.8% to 4.1% and from 11.3% to 6.0%, respectively. © The Author(s) 2021.

Applied Spectroscopy

Laser-Induced Breakdown Spectroscopy Combined with Temporal Plasma Analysis of C2 Molecular Emission for Carbon Analysis in Coal

Life expectancy of a thermally aged oil impregnated pressboard (OIP) in the presence of corrosive dibenzyl disulphide (DBDS) is studied in this work using a fast estimation method based on level of diffusion of Cu contaminant. Data from laser induced breakdown spectroscopy (LIBS) is used as the degradation parameter. Thermogravimetric analysis (TGA) is used for rapid evaluation of life expectancy at various temperatures. Aged OIP material is tested for its surface flashover breakdown strength and its thermal stability is studied by TGA and differential scanning calorimetry. Thermal activation energy is estimated using Flynn-Wall-Ozawa method and is agreement with isothermally calculated values. Aging law is derived and found to be nearly first order based on which temperature dependent life expectancy law is formulated. LIBS data of OIP collected from a failed transformer is considered to be end-of-life condition. Estimated life expectancy values using proposed fast method are compared with traditional long-aging evaluation and are in good agreement. Increase in corrosive DBDS concentration and change in aging medium using proposed method and are found to have a significant impact on life expectancy of the OIP insulation. © 1994-2012 IEEE.

Department of Electrical Engineering

IEEE Transactions on Dielectrics and Electrical Insulation

Life Expectancy Estimation of Thermally Aged Cu Contaminant-Diffused Oil Impregnated Pressboard

Single-vehicle crashes are of major concern in both developed as well as in Low Middle Income Countries due to the severity of injuries, particularly fatal accidents. In India, a significant proportion of crashes are single-vehicle crashes. The vehicles which are involved in accidents due to causes such as self skidding, hitting stationary objects, trees that are simply contributed by the drivers themselves are referred to as out-of-control single-vehicle crashes. The main objective of this study is to evaluate the risk factors associated with single-vehicle motorcycle collisions in Tamilnadu, India and identifies the unique characteristics and injury outcomes associated with these collisions. Crash dataset for the present study was prepared from the police-reported crashes for the past nine years that occurred within the state of Tamilnadu between 2009 and 2017. The identified contributory factors which influence injury severity include driver characteristics, crash-related factors, traffic-related factors, vehicle and environment-related factors. In this study, injury severity is classified into three categories, i.e. fatal, serious, and minor injuries. Since the outcome of the injury severity could be measured on an ordinal scale, a discrete ordered outcome model, an ordered logit model is applied. To summarise the results, thirteen of the studied factors are found to have a significant influence on the injury severity of drivers. Results show that the likelihood of fatal injuries increases in crashes where motorcyclists hit stationary fixed objects, hit trees, ran-off road, inclement weather conditions, urban areas. It is also found that winter season, north districts of Tamilnadu, single and two-lane roads, highways, village roads and, other district roads, daylight conditions, drivers who are younger and working-age group, overtaking from left, taking u-turn are associated with less likelihood of fatal crashes. To increase the overall safety of the roads, targeted countermeasures may be designed in light of injury severity of the drivers with respect to single-vehicle crashes also. This study provides useful insights for reducing injury severity in single-vehicle motorcycle crashes. © 2021 Informa UK Limited, trading as Taylor & Francis Group.

International Journal of Injury Control and Safety Promotion

Investigation of factors contributing to injury severity in single vehicle motorcycle crashes in India

Integration of heavy commercial road vehicle platooning concept and electric vehicle technology is a promising approach as far as sustainable freight transportation is considered. This article attempts to design a string stable controller for an electric heavy commercial road vehicle platoon by incorporating critical factors such as complete vehicle dynamics model, pneumatic brake system model and cooperative braking between friction and regenerative braking systems. The sliding mode control technique has been used for string stable platoon operation. The impact of various battery pack locations on string stability has also been analysed. The performance of the controller has been investigated by considering electric heavy commercial road vehicle platoon operation on different road slope (straight, uphill and downhill) conditions, dry and wet road conditions and vehicle load conditions. It has been observed that the battery pack location has a significant influence on string stability with respect to the platoon operating conditions. During operation on straight and level roads, string stability was achieved irrespective of the location of the battery pack. However, during downhill and uphill driving conditions, it was found that placing the battery pack near front and rear axle locations, respectively, helped in ensuring string stable platoon operation. © The Author(s) 2021.

Journal of Vibration and Control

String stable control of electric heavy vehicle platoon with varying battery pack locations

This article reports the thermal ageing of ester fluid-impregnated pressboard material along with its performance evaluation using optical emission spectroscopy (OES) and classification using machine-learning algorithms adopting laser-induced breakdown spectroscopy (LIBS). The surface discharge analysis on ester-impregnated pressboard (EIP) is studied using OES and the plasma temperature was evaluated based on the Cu I emission lines which were higher under the negative DC compared with the positive DC and AC voltages. The LIBS analysis was performed on the EIP material operated at different energy levels in order to acquire the optimal energy required to be used for its classification algorithm. The intensity ratio and electron density evaluated from LIBS studies correlated well with the plasma temperature. The lower limit of detection (LOD) calculated based on linear regression analysis for copper peak was around 3.5 times higher than the identification of carbon peak. The machine-learning techniques like principal component analysis and neural network algorithm have been performed on the LIBS spectral dataset in order to classify the ageing of EIP material. Artificial neural network adopting LIBS provided a better classification accuracy on all the aged samples compared with principal component analysis which classified only for the samples aged at higher temperatures. © 2021 The Authors. High Voltage published by John Wiley &amp; Sons Ltd on behalf of The Institution of Engineering and Technology and China Electric Power Research Institute.

High Voltage

Classification of thermal ageing impact of ester fluid-impregnated pressboard material adopting LIBS

This study uses a low-density solid-state flash lidar for estimating the trajectories of road vehicles in vehicle collision avoidance applications. Low-density flash lidars are inexpensive compared to the commonly used radars and point-cloud lidars, and have attracted the attention of vehicle manufacturers recently. However, tracking road vehicles using the sparse data provided by such sensors is challenging due to the few reflected measurement points obtained. In this paper, such challenges in the use of low-density flash lidars are identified and estimation algorithms to handle the same are presented. A method to use the amplitude information provided by the sensor for better localization of targets is evaluated using both physics-based simulations and experiments. A two-step hierarchical clustering algorithm is then employed to group multiple detections from a single object into one measurement, which is then associated with the corresponding object using a Joint Integrated Probabilistic Data Association (JIPDA) algorithm. A Kalman filter is used to estimate the longitudinal and lateral motion variables and the results are presented, which show that good tracking, especially in the lateral direction, can be achieved using the proposed algorithm despite the sparse measurements provided by the sensor. © 2021 EDP Sciences. All rights reserved.