Indian Institute of Technology Hyderabad (IITH) is a premier institute of science and technology established in 2008. IITH has been consistently ranked in the&nbsp;<a href="https://iith.ac.in/reports/" rel="noopener noreferrer">top 10 institutes</a>&nbsp;in India for Engineering&nbsp;<a href="https://www.nirfindia.org/2021/EngineeringRanking.html" rel="noopener noreferrer" target="_blank">according to NIRF</a>&nbsp;making it one of the most coveted schools for science and technology in the country.

IITH offers&nbsp;<a href="https://iith.ac.in/academics/under-graduate/">undergraduate programs</a>&nbsp;in all the classical engineering disciplines, applied sciences, design, as well as several modern interdisciplinary areas. Students are given a flexibility to explore a broad set of areas, and potentially pursue a minor or double major in a discipline that is not their own. Students who wish to seek a deeper understanding of their own discipline are strongly encouraged to get involved in cutting-edge research with the help of a faculty to mentor them, and earn an Honors in their own field.

The very foundation of IIT Hyderabad is based on&nbsp;<a href="https://iith.ac.in/research/">research and innovation</a>. The vibrant research culture is evident from the number of patents and publications that IITH produces consistently every year. IITH offers&nbsp;<a href="https://iith.ac.in/academics/programmes-offered/">graduate programs</a>&nbsp;at both a masters, and a doctoral level, in several diverse areas. There are separate programs for technology, design, science, and liberal arts. The&nbsp;<a href="https://iith.ac.in/academics/post-graduate/">MTech program</a>&nbsp;is offered in various modes and durations to cater to the ever-growing need of postgraduate level professionals in the country.

IITH encourages and supports&nbsp;<a href="https://iic-iith.netlify.app/index.html" rel="noopener noreferrer" target="_blank">innovation and entrepreneurship</a>&nbsp;at every stage. The minor program in entrepreneurship is open to all students of IITH, and many of the courses are offered by industrialists who are entrepreneurs themselves. There are various&nbsp;<a href="https://iith.ac.in/research/centres-incubators/">innovation centers and incubators</a>&nbsp;that promote entrepreneurship and help mentor young innovators. IITH has been very successful in building tie-ups with leading academic institutions around the globe.

IITH enjoys a very special relationship with Japanese universities and industries that goes beyond academic and research collaborations. In fact, some of the iconic buildings in IITH campus will carry the signature of Japanese architecture.

IITH creates a unique holistic ecosystem for education that offers interactive learning, a very flexible academic structure, cutting-edge research, strong industry collaboration, and entrepreneurship. This is an environment which enables students and faculty to translate their dreams into realities.

IIT Hyderabad

Department of Mechanical and Aerospace Engineering

Monitoring and controlling the microstructure, phases, and thermal stresses in laser cladding of materials which determine their mechanical properties is essential for ensuring repeatability and reproducibility in refurbishing engineering parts and building functional parts by layer-by-layer deposition in additive manufacturing process. Several studies have been reported on on-line monitoring of temperature, melt-pool geometry, and porosity etc. in laser powder deposition process, but only a few on the assessment of solidification morphology, microstructure, and thermal stresses. Since these features are dictated by the melt-pool lifetime, cooling and solidification rates, their effects on the evolution of microstructure and the state of ceramic particles in laser deposition of Ni-super alloy and metal matrix composites of WC and TiC are investigated in the current study. Good correlation exists between the thermal history monitored online and the solidification characteristics. Process maps based on the melt-pool lifetime as a function of laser cladding parameters for these materials are developed. On-line monitoring of thermal cycle is extended to laser welding of stainless steel and titanium which are difficult to join together due to the formation of brittle intermetallic phases, and laser polishing of thermal sprayed ceramic coating to develop a better understanding and control of these processes. Melt-pool lifetime is found to have significant effect on the crack growth in fusion welding and by optimizing the former the later could be mitigated. Similarly, the cooling rate in laser polishing of thermal sprayed ceramic coating is found to have significant influence on the surface roughness and residual stress. These studies show that the online monitoring of thermal history can be exploited for controlling the process quality and ensuring the repeatability and reproducibility in different laser material processing modalities. © 2019 ASME.

World University root node

ASME 2019 14th International Manufacturing Science and Engineering Conference, MSEC 2019

Assessment of microstructure and mechanical properties in laser cladding, welding and surface polishing through online monitoring of thermal history

Additive manufacturing (AM), known for its ability to manufacture complex shapes, is becoming an essential companion of topology optimisation (TO) to optimise the structure. However, the topology-optimised structure may result in suboptimal performance or even have features, which are difficult to manufacture in a given AM process. This study attempts to refine the outcome from TO with AM-specific considerations, such as minimum feature resolution and material continuity-related constraints by introducing a neighbourhood density function, subsequent to the solid isotropic material with penalisation approach. The four different cases have been studied to demonstrate the effectiveness of the presented approach yielding better results when compared with the conventional TO under the three-point bending test. The current study provides optimised geometry with the decreased number of voids and ensuring the minimum feature size without substantial loss in the structural behaviour and becomes the basic framework to integrate manufacturability into structural TO for the AM process. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.

Virtual and Physical Prototyping

Adopting feature resolution and material distribution constraints into topology optimisation of additive manufacturing components

The present study focuses on the mechanical behaviour of both single and double tapered scarf adhesively bonded joint of Carbon fibre reinforced polymer (CFRP) laminate as adherend subjected to tensile loading. The layup sequence of the CFRP adherend having unidirectional (UD) [00]16 and quasi [+45/−45/0/90]2S are studied. The adhesive used here is Araldite 2015 supplied by Huntsman which is a two part epoxy system of intermediate toughness grade. Here, 2D digital image correlation (DIC) technique is used for capturing the whole field longitudinal, peel and shear strain distribution over the adhesive bond line of the CFRP specimen. Further, a localised DIC measurement is also carried out using microscopic tube lens for precisely capturing strain field over concentrated zones where damage initiation occurs. The evolution of whole field strain distribution with increasing load is captured to predict the mechanical behaviour and failure mechanism of a tapered scarf joint specimen. In addition, 2-D finite element analysis (FEA) of scarf joint model is carried out for validating the DIC results. In the finite element model cohesive zone elements are used for the modelling of both adhesive layer and inter/intra laminar interface of the composite laminate. Initially, to verify the proposed numerical model, joint's initial stiffness, failure load and corresponding displacement obtained from FEA are compared against the experimental load – displacement results. Later, qualitative and quantitative comparison of longitudinal, peel and shear strain values obtained over the adhesive layer by DIC and FEA is carried out to confirm the accuracy of the DIC results. A decent correlation is found to exist between the DIC predictions and numerical results thereby confirming the accuracy of the DIC technique. Analytical solutions are also derived for the same problem based on mechanics of material and further it is compared with both FEA and DIC predictions for completeness. © 2018 Elsevier Ltd

International Journal of Adhesion and Adhesives

Prediction of mechanical behaviour of adhesively bonded CFRP scarf jointed specimen under tensile loading using localised DIC and CZM

Calophyllum inophyllum biodiesel is seems to be a potential alternative fuel for diesel engine applications due to its non-edible form, easily cultivable nature and abundant availability everywhere in the world. Isobutanol is the next generation biofuel which can be used as partial substitute to petroleum diesel or biodiesel due to its better solvency character. In the present study, a comparative assessment on diesel engine characteristics is carried out using isobutanol as an additive with diesel and biodiesel in the form of binary and ternary blends. Five blends are prepared by 20% of isobutanol with diesel and biodiesel as D80IB20 and B80IB20 along with three ternary blends of diesel-biodiesel-isobutanol using 10%, 15% and 20% concentrations of isobutanol. Experimental study in a diesel engine revealed that the brake thermal efficiency is improved by 3.19% for 10% isobutanol addition in diesel-biodiesel blends with significant improvement in brake specific fuel consumption when compared to biodiesel. All binary and ternary blends of isobutanol reduce CO emission by 13–59% than that of diesel fuel with substantial penalty in HC emission. Meanwhile, when compared to biodiesel, the oxides of nitrogen emission is decreased by 8.16% for isobutanol addition with diesel and biodiesel in terms of binary and ternary blends but higher than that of conventional diesel fuel. Furthermore, momentous improvement is observed in heat release rate during isobutanol addition for B80IB20, D70B10IB20, D70B15IB15 and D70B20IB10 fuel blends when compared to pure biodiesel. Finally, it is noted that isobutanol would be a feasible additive for the partial replacement of diesel and biodiesel in the blends for diesel engine applications. © 2018 Elsevier Ltd

Fuel

Study on isobutanol and Calophyllum inophyllum biodiesel as a partial replacement in CI engine applications

This chapter aims to explore the performance and emission characteristics of butanol isomers in order to suggest technical improvisations for their adoption as a commercial fuel in spark ignition engines. The limited availability of research works using butanol isomer blends motivates the current work involving an extensive investigation of the alternative fuels as a comparative study. Through extensive evaluation of the prevailing research works, it is found that by substituting pure gasoline fuel with butanol-gasoline blends, an increase in the carbon monoxide and hydrocarbon emissions due to the lower calorific value and higher latent heat of vaporization of butanol fuel can be obtained. However, oxides of nitrogen emissions are found to decrease with reference to that of pure gasoline fuel. The current study is extended to validate the results obtained from a review study by conducting an experimental investigation on an SI engine fueled with n-butanol-gasoline blend and isobutanol-gasoline blend. The concentrations of butanol isomers in the blends are varied from 10% to 30%, and the obtained performance and emission characteristics are compared to that of pure gasoline fuel. It is observed that the experimentally obtained characteristics are in accordance with the results obtained through comparative evaluation. © 2019 Elsevier Ltd. All rights reserved.

Advanced Biofuels: Applications, Technologies and Environmental Sustainability

Investigation on the effect of butanol isomers with gasoline on spark ignition engine characteristics

The effect of the Knudsen layer in the thermal micro-scale gas flows has been investigated. The effective mean free path model has been implemented in the open source computational fluid dynamics (CFD) code, to extend its applicability up to slip and early transition flow regime. The conventional Navier-Stokes constitutive relations and the first-order non-equilibrium boundary conditions are modified based on the effective mean free path, which depends on the distance from the solid surface. The predictive capability of the standard 'Maxwell velocity slip-Smoluchwoski temperature jump' and hybrid boundary conditions 'Langmuir Maxwell velocity slip-Langmuir Smoluchwoski temperature jump' in conjunction with the Knudsen layer formulation has been evaluated in the present work. Simulations are carried out over a nano-/micro-scale backward facing step geometry in which flow experiences adverse pressure gradient, separation and re-attachment. Results are validated against the direct simulation Monte Carlo (DSMC) data, and have shown significant improvement over the existing CFD solvers. Non-equilibrium effects on the velocity and temperature of gas on the surface of the backward facing step channel are studied by varying the flow Knudsen number, inlet flow temperature, and wall temperature. Results show that the modified solver with hybrid Langmuir based boundary conditions gives the best predictions when the Knudsen layer is incorporated, and the standard Maxwell-Smoluchowski can accurately capture momentum and the thermal Knudsen layer when the temperature of the wall is higher than the fluid flow. © 2019 by the authors.

Fulltext

Micromachines

Modeling of knudsen layer effects in the micro-scale backward-facing step in the slip flow regime

RC elements are often subjected to combined actions including torsion under seismic events. Understanding the behavior of RC members under combined actions including torsion is essential for safe design. Behavioral predictions of RC columns under combined loading can be improved by including the bidirectional stress effects. The objective of this work is to propose the improved combined actions softened-membrane model (CA-SMM) for predicting the behavior of RC elements under combined torsion (T) and shear loading (V). In this approach, the rectangular cross section is modeled as an assembly of four cracked shear panels. The applied external loads are distributed among these four shear panels. This assumption helps in reducing the complex stress state from combined loading to four different simple stress states on these panels. Additional equilibrium and compatibility conditions are imposed, and the system of nonlinear equations are solved by using an optimization technique called the gradient descent method. The developed improved model (CA-SMM) is validated with the experimental data available in the literature. After that, an interaction between the shear and torsion is developed to understand the behavior under various combinations of torsion and shear. A parametric study is carried out for understanding the effect of various sectional parameters such as longitudinal reinforcement ratio, transverse reinforcement ratio, and concrete strength. The predictions of the improved model had a close correlation with the test results. © 2018 American Society of Civil Engineers.

Department of Civil Engineering

Journal of Structural Engineering (United States)

Optimization-Based Improved Softened-Membrane Model for Rectangular RC Members under Combined Shear and Torsion

A numerical investigation of Knudsen layer effects in high-speed flows in a rarefied flow regime has been carried out. The conventional compressible flow computational fluid dynamics (CFD) solver is reformed based on the effective mean free path model to augment the validity of the Navier-Stokes-Fourier equations in the slip-transition flow regime. The mean free path is expressed as a function of the distance from the surface and local flow gradients, and has been used to modify linear constitutive relations, as well as slip and jump boundary conditions, to incorporate Knudsen layer correction. The improved solver has been validated against direct simulation Monte Carlo (DSMC) data of benchmark test cases of hypersonic flow (Mach number=6.1 and 12.7) over a flat plate in the slip-flow regime (Knudsen number=0.004), and Mach 10 flow over a circular cylinder in the transition flow regime (Knudsen number=0.25). The results show that the accuracy of the conventional CFD solver has been significantly improved due to the implementation of the Knudsen layer approach in the near-wall region and the bulk-flow region. Crucial nonlinear trends are captured in the nonequilibrium regions of high-speed flows, such as shock waves and the Knudsen layer. The location of an oblique shock around the flat plate is accurately captured and overall, the Knudsen layer incorporation has exhibited good agreement with the DSMC with deviations within 4% in the upstream region of the cylinder. © 2019 American Society of Civil Engineers.

Journal of Aerospace Engineering

Implementation of Knudsen Layer Phenomena in Rarefied High-Speed Gas Flows

Effect of the Knudsen layer (KL) on surface and bulk flow properties is investigated for the hypersonic flow applications in the slip flow regime. Knudsen Layer formulation is incorporated within an open source computational fluid dynamics framework, OpenFOAM. Navier-Stokes (N-S) constitutive relations, and first order slip and jump boundary conditions are modified based on the effective mean free path, which is dependent on the geometry of an obstacle and local flow gradients. This new approach is evaluated for three configurations: (1) the flate plate with M = 6.1 and Kn = 0.004, (2) the sharp wedge, with M = 10 and Kn = 0.01, and (3) the cylinder, with M= 10 and Kn = 0.05, with argon and nitrogen as working gases. Simulation results are validated against published Direct Simulation Monte Carlo (DSMC) and experimental results. The surface velocity predicted by new formulation give good agreement with the DSMC data especially for the flat plate case. It has also shown maximum improvement of 47 % at θ = 90-for cylinder case over a conventional solver. Knudsen layer formulation have improved the results in the bulk flow region as well. Simulation results convey that our approach greatly improves the predictive capabilities of the compressible N-S-F solver upto early transition flow regime. The current work is significant from the perspective of accurate thermal design of hypersonic vehicles. © 2019 Author(s).

AIP Conference Proceedings

The effect of Knudsen layer on rarefied hypersonic gas flows

Grid fins are unconventional control surfaces consisting of an outer frame supporting an inner grid of intersecting planar surfaces. Although afflicted with higher drag, these have been credited for their enhanced lifting characteristics at high angles of attack and high Mach numbers, alongside reduced hinge moments accounting for the recent upsurge in their usage on numerous aerospace applications. Present investigations carry out elaborate flow field visualization and characterization underlining the rudimentary physics through a sequence of subsonic numerical simulations performed at different angles of attack and different gap (between the members) to chord ratios on a simplified grid fin variant called cascade fin. The study makes use of a new nondimensionalization technique called cumulative nondimensionalization to decipher the effect of cascading on individual members of the fin. Hence, after a comprehensive examination of the aerodynamic coefficients, pressure coefficient distribution, pressure gradient, velocity gradient, boundary layer velocity profile, and flow field visualization, the study elucidates physics associated with hastened stall angle, augmented lift-drag, and bounded efficiency accretion for gap increment. Copyright © 2019 by ASME.