Thesis Colloquium
2024-03-13 14:00 - 15:00 UTC
Asymptotic Modelling of Carbon Nanotube (CNT) and CNT-reinforced composite structures using strain gradient formulations

Research Supervisor: Dineshkumar Harursampath

Thesis Abstract

Carbon nanotubes (CNTs) have garnered attention for their remarkable mechanical, thermal, and electrical properties, making them valuable in various applications. CNTs are particularly advantageous in aerospace structures as reinforcements in polymer matrix composites, enhancing structural strength while reducing weight. Furthermore, they offer the potential for multifunctionality, integrating structural, thermal, and electrical functionalities within components like wings. However, accurately modelling CNT behaviour poses challenges, especially considering their application in larger-scale aerospace structures. While accurate, molecular dynamics and molecular structural mechanics are computationally intensive and limited in length scale. In this context, the present research proposes reduced-order continuum structural models using the Variational Asymptotic Method (VAM) to study CNT and its composite structures while incorporating length scale effects using strain-gradient formulations.

Using VAM, single-walled CNTs (SWCNTs) were first analysed by considering them as straight, hollow, circular tubes in a local continuum framework. This tube model accounts for the geometrically nonlinear behaviour of standalone CNT when subjected to bending and buckling loads. Cross-sectional ovalisation leading to nonlinear bending and buckling behaviour has been studied. Combined loading cases of bending and compression and torsion and compression and bending and torsion have been examined. The study aims to provide insights into the 3-D nonlinear deformation behaviour of SWCNTs, offering a more efficient approach for evaluating CNTs in aerospace composite applications.

In the next step, recognising the significance of the structure's small size (such as used in MEMS, NEMS, and sensors), the non-classical theories, such as the Modified Strain Gradient Theory, which account for the size effect in the material, have been employed to develop a pioneering beam and plate models tailored for CNT-reinforced composite structures. Emphasising the critical nature of size effects, characterised by length scale parameters, this study delves into the nuances of the length scale effects in nanoscale structures. To develop the asymptotically-correct strain-gradient beam model, a prismatic beam with a rectangular cross section has been considered to derive zeroth-order and subsequent higher-order models while capturing the strain-gradient effects. Notably, this work is the first application of non-classical theories in developing VAM-based beam models. Different orders for length scale parameters have been considered, and the validity of each choice is scrutinised, followed by guidance on the appropriate choice of the length scale parameters.

Following the development of the strain-gradient beam model, a modified strain gradient theory-based plate model has also been developed using VAM, which is again a first-of-its-kind work in the context of VAM and reduced-order structural models. Using the variational methods, fourth-order ordinary differential equations were obtained for the non-classical case, and similarly, an additional set of boundary conditions (non-classical) were also derived. The warping solutions and the plate stiffnesses are obtained by solving these governing differential equations and boundary conditions. It was noted that the material length scale parameters appear only in the bending and twist stiffness terms. Further, the classical results can be derived by setting the material length scale parameters as zero. Zeroth- and first-order approximations have been derived, followed by detailed validation of the results with literature for bending and buckling load cases. Parametric studies involving variations in thickness and plate width have been conducted to assess their influence on mechanical behaviour. The developed plate model is then applied to CNT-reinforced composites, and their bending and buckling studies have been carried out. The parametric studies have also considered evaluating all influencing parameters like CNT volume fraction, material length scale parameter, plate thickness and width.

Full Meeting Link: https://teams.microsoft.com/l/meetup-join/19%3ameeting_ZWY1NmM0MGItODQ5ZS00ZmE4LTk5YjMtYWMyMGQ3ZGE1ODlh%40thread.v2/0?context=%7b%22Tid%22%3a%226f15cd97-f6a7-41e3-b2c5-ad4193976476%22%2c%22Oid%22%3a%22eb59112f-967f-4f24-8739-385858c5592e%22%7d

Venue: STC Seminar Hall, 1st Floor, Dept of Aerospace Engineering

AE Seminar
2024-03-04 14:30 - 16:00 UTC
Nonequilibrium reacting flows: First principles based modeling for chemical kinetics and hydrodynamics

Speaker
Dr. Narendra Singh
Postdoc Research Associate, Standford University

Abstract
Predicting state of the gas hitting vehicles flying at hypersonic speeds (Mach ~5) is challenging and is an exciting area of research. Hypersonic flows create shock waves, which compress and heat the surrounding gas to high-temperatures, nearly thousands of Kelvins. At these high temperatures, air molecules (nitrogen and oxygen) dissociate into atomic species. Predicting the extent of dissociation and recombination of atomic species is important since the state of the gas near the vehicle surface determines heating rates and gas-surface chemistry that damages the heat shield. Since experiments in ground test facilities do not mimic such extreme flight conditions, numerical simulation plays an important role. Predictive numerical simulations require accurate reaction chemistry models. Computational models developed thus far range from simple empirical models fit to limited experimental data to models with millions of input parameters that track individual quantized energy state transitions. The level of model fidelity required for accurate engineering analysis remains an open question of active research. Models coupling internal energy and dissociation chemistry tend to be developed at either the kinetic scale or the continuum scale. In this work, we develop new nonequilibrium models for shock heated flows that are analytically consistent between kinetic and continuum scales and are based on recent ab-initio data, applicable to large-scale CFD and direct simulation Monte Catlo (DSMC) simulations.

Nonequilibrium Hydrodynamics: The Navier-Stokes equations, typically employed even at strong non-equilibrium conditions, wherein thermodynamic fluxes such as stresses and heat flux vector are based on linear irreversible thermodynamics, not be accurate in multiscale and multiphysics scenarios encountered in hypersonic flows. Similarly, the Navier-Stokes equations are known to breakdown in rarefied (low density) gas flows. Therefore, a new formalism is proposed to circumvent these issues, which can also benefit, hybrid methods that can combine continuum description using the Navier-Stokes equations and microscopic description, necessary for efficient high-fidelity numerical simulations. Other wide range of physics problems such as nano-scale flows, plasma physics modeling, and general complex gas flows can also benefit from the proposed new non-equilibrium hydrodynamic formalism.
Brief Bio of Speaker:
Dr. Narendra Singh graduated with a PhD (and MS) in Aerospace Engineering (with minor in Mathematics and Chemistry) from University of Minnesota. Narendra obtained his undergraduate degree (with Honors) in MechE from IIT Bombay. In his doctoral thesis, Narendra developed chemical kinetics models for DSMC and CFD using first principles-based approach. In addition, Narendra (along with Prof.Agrawal) has developed higher order equations for rarefied and strong nonequilibrium flows, known as O-13 and O-Burnett equations, where O ‘refers’ to Onsager due to the consistency of equations with Onsager’s reciprocity principle. Narendra Singh did his 2 years postdoc in MechE at Stanford, where his research spanned particle-laden flows, carbon sequestration, and ultrafast chemistry at SLAC. Currently, he is a postdoc research associate at Center for Hypersonic, UIUC, and developing reduced order models for chemical kinetics.

AE Seminar
2024-02-05 14:00 - 15:00 UTC
Innovations in Aerospace Systems – Current Research (including Artificial Intelligence) and Future Challenges

Speaker
Prof. Krishna Dev Kumar
Professor of Aerospace Engineering
Director of Artificial Intelligence for Aerospace Systems Laboratory
Toronto Metropolitan University, Canada

Abstract
Aircraft and spacecraft are highly complex systems, comprising various subsystems such as flight control, propulsion, and power. These subsystems feature Multiple Input & Multiple Output (MIMO) configurations and exhibit highly nonlinear characteristics. Over recent years, there has been a growing demand for aerospace systems with improved performance, fault tolerance, and enhanced autonomous capabilities. This presentation explores how fault diagnosis, prognosis and artificial intelligence can address these requirements. It delves into model-based, data-driven (artificial intelligence), and hybrid approaches, which have been proposed for fault diagnosis and prognosis. Furthermore, the author has proposed novel methods to meet these evolving demands. These innovative techniques, including the Covariance-based adaptive unscented Kalman filter (CAUKF), Binary grid covariance adaptive Kalman filter (GAUKF), Reinforced Unscented Kalman Filter (an integration of UKF and Reinforcement Learning techniques), and Growing Neural Networks (GNN), hold promise for aerospace system enhancement. The presentation will feature case studies illustrating the application of these methods in spacecraft attitude and orbit control systems, as well as aircraft engines. By examining the latest advancements and methodologies, attendees will gain insights into the pivotal role these techniques play in enhancing aerospace system reliability and efficiency, ultimately addressing current research challenges and shaping the trajectory of future aerospace systems.
Brief Bio of Speaker:
Dr. Krishna D. Kumar is a Professor of Aerospace Engineering and Director of Artificial Intelligence for Aerospace Systems (AIAS) Laboratory at Toronto Metropolitan University, Canada. Additionally, he is the Founder and President of iSAC Systems Inc, a leader in Artificial Intelligence (AI), Internet-of-Things (IoT), and Smart Systems since 2010. Prof. Kumar has made outstanding contributions with major impact in the areas of spacecraft dynamics and control, fault diagnosis and prognosis, artificial intelligence, and predictive analytics with over 250 publications including 5 books, 14 intellectual properties, and four patents. His AI and IoT products have been deployed across diverse industries, including aerospace, transportation, and waste management. His illustrious career boasts several remarkable achievements, including the development of AI-powered predictive analytics for the NASA Kepler Spacecraft and Aircraft Engines, the world's first 100-gram miniature satellite, and the world's first miniature IoT monitoring systems for Bombardier Trains, and Safran Aircraft Landing gears. Prof. Kumar’s exemplary contributions to the field have been widely recognized with numerous national and international awards, including the prestigious Canada Research Chair Award, Ontario Early Researcher Award, Associate Fellow of American Aeronautics and Astronautics, Japan Society for the Promotion of Science Fellow, Japan Science and Technology Agency Fellow, Member of the International Academy of Astronautics in France, the Sarwan Sahota Ryerson Distinguished Scholar Award, and the Eminent Alumnus Award from Veer Surendra Sai University of Technology, Sambalpur, India. Furthermore, Prof. Kumar is the Co-Editor of Acta Astronautica and Transactions of the Japan Society for Aeronautical and Space Sciences.
Venue
STC Seminar Hall, Dept. of Aerospace Engineering

India - USA Lecture Series on Aging Aircraft (IULSAA)
2019-11-27 00:00 - 2019-11-29 00:00 (Asia/Kolkata)
27 – 29 November 2019
Department of Aerospace Engineering,
Indian Institute of Science,
Bangalore, India

INDIA-USA LECTURE SERIES ON AGING AIRCRAFT (IULSAA) Venue: Satish Dhawan Auditorium, IISc, Bengaluru, India

TECHNICAL PROGRAM

November 27, 2019

08.00 am - 09.00 am Registration 09.00 am - 09.50 am Inaugural Session
Plenary -Session Chair:
09.50 am - 10.20 am First Plenary Talk Sustenance of Aircraft Fleet Through Aging Management Air Marshal Shashiker Choudhary, Air Officer-in-ChargeMaintenance, Air Headquarters, New Delhi 10.20 am - 10.50 am Second Plenary Talk Environment Effects on Aging of Structures William Nickerson, Office of Naval Research, Arlington, USA 10.50 am - 11.20 am Coffee/Tea Break

Session I Chair:
11.20 am - 12.20 pm Aging Aircraft: An Introduction Dr S G Sampath, FAA, USA - Retired 12.20 pm - 01.20 pm Airframe and Aeroengine Fatigue under Extended Service Usage Dr R Sunder, Bangalore Integrated System Solutions, Bangalore 01.20 pm - 02.00 pm Lunch

Session II A Chair:
02.00 pm - 03.00 pm NDE and SHM for Aerospace Applications Dr Krishnan Balasubramaniam , IIT Madras 03.00 pm - 04.00 pm Aging Aircraft Engines Dr Prakash Patnaik, National Research Council, Canada 04.00 pm - 04.15 pm Coffee/Tea Break

Session II B Chair:
04.15 pm - 05.15 pm Overview of Helicopter Fatigue Mr. Ugo Mariani, Leonardo Helicopters, Italy 06.00 pm - 08.00 pm Cultural Program-An Evening of Carnatic Music Carnatic Music Concert by Prof. Sankaran Mahadevan, Vanderbilt University 08.15 pm onwards Dinner at IISc Guest House Lawns

November 28, 2019

Session III A Chair:
09.00 am - 10.00 am Corrosion Monitoring Dr Prakash Mangalgiri, Visiting Professor, IIT Kanpur 10.00 am - 11.00 am Review and Assessment of Airframe Repair Schemes Dr Jayanth Kudva, Next Gen Aeronautics, USA 11.00 am - 11.30 am Coffee/Tea Break

Session III B Chair:
11.30 am - 12.30 pm Monitoring Aircraft Load Spectrum Towards an Integrated Structural Health Management Prof. Afzal Suleman, University of Victoria, Canada 12.30 pm - 01.30 pm Lunch

Session IV Chair:
01.30 pm - 02.30 pm Electromagnetic NDE Activities at MSU on Aging Aircraft NDE Prof. Lalita Udpa, Michigan State University, USA 02.30 pm - 03.30 pm Digital Twin Technology for Aircraft Health and Operations Management under Uncertainty Prof. Sankaran Mahadevan, Vanderbilt University, USA 03.30 pm - 04.00 pm Coffee/Tea Break

Session V Chair:
04.00 pm - 05.00 pm Effect of Newly Promulgated, Environmental Rules Dr Prakash Patnaik, National Research Council, Canada 05.00 pm - 06.00 pm Aging of Aircraft Electrical Wiring H R Sudarashan Prasad, Centre of Excellence in Aerospace and Defence, Bangalore 07.30pm onwards Banquet Dinner at Kirloskar Hut, Bangalore Golf Club, Bangalore

November 29, 2019

Session VI Chair:
09.00 am - 10.15 am Human Factors in Aircraft Maintenance and Inspection Prof. Colin Drury, SUNY, Buffalo, USA 10.15 am - 11.15 am Aging Avionics Shri Yogesh Kumar, HAL, Bangalore - Retired 11.15 am - 11.30 am Coffee/Tea Break

Session VII Chair:
11.30 am - 12.30 pm Technology Insertion into a Combat Aircraft: Opportunities And Challenges Dr K Vijayaraju, Aeronautical Development Agency (DRDO) 12.30 pm - 01.30 pm Structural Life Management in a Combat Aircraft Dr A R Upadhya, Former Director, CSIR-NAL and Dr Mangalgiri, Visiting Prof, IIT, Kanpur 01.30 pm - 02.30 pm Lunch

Session VIII Chair:
02.30 pm - 03.00 pm Presentation from DGCA 03.00 pm - 03.30 pm Presentation from Private Airlines 03.30 pm - 04.00 pm Coffee/Tea Break 04.00 pm - 04.30 pm Feedback Session

Website URL

Assessment of resolvent analysis as a tool for active flow control design
2019-02-22 16:00 - 18:00 (Asia/Kolkata)
Simon Tödtli
Graduate Aerospace Laboratories
California Institute of Technology

Reducing turbulent drag on engineering surfaces such as ship hulls or pipes has the potential of tremendous energetic savings. However, tractable and efficient flow models for designing drag reduction mechanisms, such as active feedback flow control or compliant surfaces, are currently missing in the literature. This talk describes a flow model (Luhar et al, J. Fluid Mech. 2014) based on the resolvent analysis of McKeon & Sharma (J. Fluid Mech. 2010) and assesses its potential for designing active feedback flow control schemes for drag reduction in incompressible wall-bounded flows. The assessment is based on a generalized version of the well-known opposition control scheme (Choi et al, J Fluid Mech. 1994), which allows for a phase-shift between the sensor measurement and the actuator response. The resolvent model predicts that the phase shift strongly affects the attainable drag reduction and suggests that a range of nonzero phases offer improved control effectiveness. We validate these predictions by means of a parametric DNS study and show that the response of the full nonlinear system to opposition control with various phase shifts very closely follows the low-order model predictions. We close with a short discussion of the structural features of various controlled flows, which provide first insights into the role of the phase in the real flow and the physics of drag reduction.

Overview of Some Industrial Applications of University-Based Thermo-Fluids Research
2019-02-20 03:00 - 17:00 (Asia/Kolkata)
Barron and R. Balachandar

University of Windsor, Canada

Wednesday, 20th February, 2019, 3.00 PM

The tools of modern-day thermo-fluids research open up a pl ethora of opportunities for interactions between university researchers and industrial end-users. On the experimental side, measurements include a wide range of devices, ranging from simple flow meters, pressure gauges, thermocouples and hotwires to LDA, LDV, volumetric and time-resolved PIV. The fundamentals of numerical modeling of fluid flows and heat transfer are also well-established and there are many in-house researches, commercial and open-source codes available today. Both approaches, experimental and computational, produce an enormous amount of data which needs to be processed and visualized. Techniques for post-processing of large datasets will be discussed, including POD and various fluid structure identification criteria. While academic researchers may strive to develop a better understanding of the flow physics, industrial researchers want to know how to improve their products. These goals are not mutually exclusive. Examples to illustrate the use of these tools and techniques will be drawn from recent work with industrial partners in the automotive, food processing, greenhouse, mold making and electronics industry.

Biography:

Dr. Ron Barron, is Professor Emeritus in the Department of Mathematics and Statistics, Faculty of Science, at the University of Windsor, with cross-appointment to the Department of Mechanical, Automotive and Materials Engineering. He holds BA and MSc degrees in Mathematics from University of Windsor, PhD degree in Mathematics from Carleton University and MSc in Engineering from Stanford University. He is currentlyDepartment Head, Associate Dean and Interim Dean of the Faculty of Graduate Studies and Research, Associate Vice-President Research and Director of Research Services. His research spans across several disciplines, notably applied mathematics, mechanical engineering, civil engineering, computer science and physics, focusing on Computational Fluid Dynamics (CFD) and Numerical Heat Transfer (NHT), with special interest in software development and industrial applications.

Dr. Ram Balachandar, is Professor in the Faculty of Engineering at the University of Windsor with appointments in the Department of Civil and Environmental Engineering and in the Department of Mechanical, Automotive and Materials Engineering. Over the last 25 years, Dr. Balachandar’s research focus has been on thermo-fluids engineering and fluid-structure interaction using both experimental and computational tools.

Co-ordinator – Dr. P.S. Kulkarni, Department of Aerospace Engineering, IISc

All are welcome:

By-pass transition and re-laminarization - Two sides of the same coin
2019-02-13 16:00 - 17:00 (Asia/Kolkata)
Name of the Speaker: Prof. Garry Brown, Dept. of Mechanical and Aerospace Engineering, Princeton University

Title: By-pass transition and re-laminarization - Two sides of the same coin

Date & Time: Wednesday, 13 February 2019, 4:00 - 5:00 PM

Venue: Auditorium, Department of Aerospace Engineering, IISc, Bangalore

Abstract:

Transition and re-laminarization are good examples of the complexity of many technologically important flows for which predictions from the physics are needed. Two routes to ‘transition’ for a laminar boundary layer are well-known: one, the classical route via amplifying Tollmien-Schlichting (T-S) instability waves (and the onset and merging of ‘turbulent spots’), the other, ‘By-pass’ transition, (a description coined by Morkovin for the absence of amplifying T-S waves). Boundary layer transition has been identified with a rapid increase in wall shear stress (and heat-transfer) but details of the actual mechanisms by which the wall shear stress increases have been elusive. The talk will describe new insights into ‘roughness induced transition’, (characteristic of Bypass transition). In particular it will describe from a vorticity point of view a final phase which leads to chaotic vorticity (characteristic of turbulence) and a rapid increase in the shear stress at the wall in the absence of any 2D T-S waves. The unravelling of what occurs is based on the vorticity transport near the wall (which was elucidated initially by numerical studies of turbulent channel flow). A similar point of view, but applied to the ‘opposite side of the same coin’, namely, ‘re-laminarization’ has allowed new insights into why re-laminarization occurs in a spatial turbulent boundary layer subject to a highly favourable pressure gradient. It has also been found not to occur in a temporal, boundary layer (Rayleigh flow) having the same initial and subject to a rapid acceleration of the plate (also a source of spanwise vorticity), which is comparable with the acceleration of the free stream flow in the spatial case. The reason for the different behavior is described and readily appreciated

Speaker:

Prof. Garry Brown is the Emeritus Robert Porter Patterson Professor of Engineering at Princeton University. He received a first class Honors Degree in Engineering from the University of Adelaide in 1964, was awarded a Rhodes scholarship, completed his D.Phil at Oxford and was then a research fellow/senior research fellow at GALCIT, Caltech. In 1971 he returned to the University of Adelaide and in 1978 returned to Caltech as full professor. He was asked to serve as Director of the Australian Aeronautical Research Laboratory and held this position from 1981-1990 after which he joined the faculty at Princeton, serving as Chair of the Department of Mechanical and Aerospace Engineering from 1990 to 1998. His best known work is in the study of turbulence. Fifty years after the inception of the Journal of Fluid Mechanics, his 1974 paper with Professor Roshko “On density effects and large structure in turbulent mixing layers,” was the most frequently cited paper in the history of the journal. After joining Princeton he explored new research horizons while continuing his abiding interest in turbulence. In 2016 he was the Clark Millikan Visiting Professor at Caltech and taught a course with Professor Roshko and in 2017 he was the Satish Dhawan Visiting professor at the Indian Institute of Science in Bangalore where he also taught a course on turbulent shear flows. He has also made significant contributions, as a consultant in Australia and to the American aerospace industry, that include the root cause of extreme propeller-induced-vibration of the Lysaght Enterprise, the root cause of failure and redesign of the solid rocket motor for the Titan IV, the cause of early failure and development of the thrust-vectoring system for AIM-9X and the resolution of critical issues for Tactical Tomahawk and for the Standard Missile-3 Programs. He played a leading role in the failure investigation and redesign of early air-cooled test cells for the after-burning F100 engine. He is a Fellow of the Institution of Engineers of Australia, Fellow of the American Physical Society, and a Fellow of the AIAA

ALL ARE WELCOME

High Tea @ 5 PM

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P.S. The distinguished lecture series is COMPULSORY for all students (both M.Tech and Ph.D.) of the AE department.

Symposium on Classical to Computational Aeroelasticity
2018-09-10 - 2018-09-12
Course Coordinator

Prof. Kartik Venkataraman

Course Instructors

Prof. Rakesh Kapania (Virginia Tec, USA)

Abstract

Transition from the classical aeroelasticity based on the linear aerodynamic equations to the computational aeroelastcity based on the computational fluid dynamics using the non-linear aerodynamic equations began in mid 70s. Classical aeroelastcity which is less computer intensive is still progressing towards use in the preliminary design for more complex configurations. Leveraging from the rapid advances in high performance computers, computational aeroelasticity which focuses on accuracy by overcoming the limitations of the linear aerodynamic theory is growing on-par with the classical aeroelasticity. Present symposium addresses progress to date in both classical and computational aeroelasticity.

Event Schedule

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Platinum Jubilee
2017-12-14 - 2017-12-15
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Awardees List

[SEMINAR]: "Uncertainty Quantification for Reliability Analysis and Health Management in Engineering Systems"
2016-12-19 11:00 - 13:00 (Asia/Kolkata)
The Chairman Department of Aerospace Engineering Cordially Invite you for a Lecture

Title: Uncertainty Quantification for Reliability Analysis and Health Management in Engineering Systems

Speaker:
Professor Sankaran Mahadevan
John R. Murray Sr. Chair in Engineering
Professor of Civil and Environmental Engineering, Professor of Mechanical Engineering
Director, NSF-IGERT Doctoral Program in Reliability and Risk Engineering and Management
Co-Director, Laboratory for Systems Integrity and Reliability
Vanderbilt University, Nashville, TN, USA

Event Date:

Monday, December 19, 2016 - 11:00
