A Study on Fluid Flow, Heat Transfer, and Scaling Laws of Breeder Blanket Concept of Fusion Reactor 22 Mar 2024 | Bernoulli, ME Department |
Seminar of Taaresh Taneja (PhD student, University of Minnesota) on Non-Equilibrium Plasma and its Use in Combustion: A Modeling Perspective Abstract: Non-equilibrium or Low Temperature Plasma is a state of a gas which is characterized by a
Brief Bio-data of speaker:
13 Mar 2024 | ME Dept Auditorium |
Prof. Shyamprasad Karagadde has been awarded the Faculty Award for Research Excellence (FARE) instituted by the class of 1973 on the occasion of Golden Jubilee. 12 Feb 2024 | |
PhD viva-voce examination of Ritesh Dadhich Chairman : Prof. Chandra S. Yerramalli, Department of Aerospace Engineering, IIT Bombay |
Ph.D. defence of Amir Hamza Siddiqui on Novel cruciform specimen design and plastic flow behaviour of anisotropic material under in-plane biaxial loading Chairman: Prof. Chandrasekher Yerramalli (Dept of Aerospace Engg, IIT Bombay) |
Ph.D. defense of Mr. Harish Veeravenkata on Ab-initio Modelling of Materials for Energy Applications Abstract: To predict the properties of phonon and electron transport, we employ first-principles calculations. This involves considering various scattering mechanisms such as phonon-phonon, phonon-boundary, and phonon-isotope interactions, and utilizing the Boltzmann transport equation. The scattering rates associated with phonon-phonon interactions are determined by conducting calculations based on both harmonic and anharmonic lattice dynamics. In order to perform these calculations, we obtain harmonic and cubic force constants, which are necessary inputs, through density functional theory and density functional perturbation theory calculations. The thermal transport properties of the recently synthesized high-pressure phase of BNC2 are investigated using the iterative solution of the Boltzmann transport equation with inputs from density functional theory calculations. The thermal conductivity of BNC2 is found to be extremely sensitive to pressure, and the thermal conductivity at room temperature under 20 GPa pressure is over 1400 W/m-K which is more than 40% higher than the cor- responding value at 0 GPa. Similar to diamond, the origin of this extremely high thermal conductivity is rooted at large phonon group velocities, which gives rise to fluid-like hydrodynamic thermal transport in BNC2. However, unlike diamond, the large isotope disorder of boron atoms in BNC2 results in a large phonon-isotope scattering, which renders hydrodynamic flow prevalent only in isotopically pure samples at length scales of up to 65 μm at 100 K. Date: 1 Feb 2024 External Examiner: Prof. Abhishek Singh, IISc Supervisor: Prof. Ankit Jain 01 Feb 2024 | ME Auditorium |
PhD defense of Mr. Vishwas Divse on Progressive Damage Modeling of Fiber Reinforced Plastic Composites including Drilling-induced Damage Abstract: This study focuses on the development of mesoscale progressive damage models (PDMs) based on continuum damage mechanics, incorporating well-established failure criteria such as 2D Hashin, 3D Hashin, Puck, and LaRC05. These PDMs take into account various damage modes, including matrix cracking, matrix crushing, ber breakage, and fiber kinking. Additionally, they incorporate shear non-linearity, in-situ strengths, and mixed mode fracture and employ a numerical search algorithm to determine the kink-band plane and matrix fracture angles. The PDMs were implemented within the Abaqus/explicit finite element framework using the VUMAT subroutines written in FORTRAN. Specifically, finite element method (FEM) based models were employed to de ne pre-existing ber or matrix damage in the subroutines. The PDMs were first verified with single-element and mesh dependency tests. Furthermore, FEM-based models were developed to simulate open-hole tension (OHT) and open-hole compression (OHC) tests that aim at predicting damage propagation and the corresponding limiting strength of the FRP laminates. Lastly, both FEM-based simulations and experiments were conducted to analyze drilling-induced damage and its impact on the OHT strength of FRP laminates. The study reveals that the stress concentration factor (SCF) substantially increases with an increase in hole size. Interestingly, laminates can be designed with SCF (<3) lower than an open hole in a finite isotropic plate by suitable stacking of on- and off-axis plies. When subjected to tension, an open hole lamina always fails due to matrix cracking along the ber direction. However, laminates demonstrate complex failure interactions involving multiple damage mechanisms. During OHT tests, ply-blocked laminates show around 30% higher strength and fracture strain than non-ply-blocked laminates due to delayed damage propagation. The ply-blocked laminates display reduced sensitivity to hole size, resulting in a 14.3% reduction in OHT strength when the hole size increases from 6 to 9 mm, compared to a 21.14% reduction in the non-ply-blocked laminates. In OHC tests, ber splitting and kinking initiate at regions of maximum in-plane shear stress and propagate due to longitudinal compression and in-plane shear stress. The ultimate failure of 0 degree dominant and quasi-isotropic layup is governed by ber kinking in 0 degree plies, while matrix cracking and delamination in 45 degrees plies contribute to the nal failure of shear dominant layups. Notably, the quasi-isotropic layup was observed to be more sensitive to hole (or notch) size than the other laminates. Furthermore, it was found that drilling-induced damage increases with feed rate and drill-bit size, while cutting speed has a slight mitigating effect. Drilling-induced damage predominantly propagates along the ber orientation of the exit ply in the laminate. The digital image correlation (DIC) analysis shows heightened strain concentration at the location of drilling-induced damage, resulting in accelerated damage propagation and reduced overall laminate strength. This leads to up to a 15% decrease in open-hole tension (OHT) strength and a 7-11% decrease in open-hole compression (OHC) strength. Drilled laminates experience a significant strength reduction of up to 50% compared to plain laminates due to the combined effect of the hole and drilling-induced damage. Therefore, designing FRP laminates with holes and pre-existing damage requires careful consideration. The proposed models show predictions within a 10-15% deviation from experimental results for OHT tests, OHC tests, and drilling. These models hold the potential for solving engineering problems, especially when extended to account for cyclic loading scenarios. External Examiner: Prof. Naresh Bhatnagar, IIT Delhi |
Final PhD viva-voce examination of Mr. Ritam Chatterjee Title of the thesis: Development of Mean-Field and Full-Field Crystal Plasticity Phase-Field Models to Investigate Dynamic Recrystallization Date: Wednesday, Jan 31, 2024 Details of the examination panel are as follows: Chairperson: Prof. Alok Shukla, IIT Bombay |
Prof. Prasanna Gandhi honoured in recognition of his contribution to ISRO's first moon landing mission. 19 Jan 2024 | |
Talk by Prof. G. C. Nandi, Dean (Acad) and Head of the Department, Dept. of Information Technology, IIIT Allahabad, on Language Conditioned Human Robot Interactions as per the following schedule today Time: 4:00 PM Venue: ME Dept Auditorium Abstract: The pursuit of creating robots that seamlessly comprehend and execute natural language directives has remained a longstanding aspiration within the realm of artificial intelligence. While the burgeoning advancements in generative AI and Large Language Models (LLMs) have catalyzed recent explorations in this domain, hardly any endeavors have successfully materialized a tangible embodiment of such technology. These exceptional instances involve robots that operate within our physical world, proficiently responding to a vast spectrum of intricate linguistic commands. The primary impediment to achieving this ambitious goal lies in the intricacy of commanding a robot to identify and manipulate objects within an unfamiliar environment, relocating them to a prescribed destination. This task poses an immense challenge for robots striving to serve as valuable aides in human-centric settings, as it necessitates the mastery of multiple facets spanning the diverse spectrum of robotics disciplines. Conquering this challenge mandates adeptness in perception, language comprehension, navigation, and dexterous grasp manipulation. Within the context of this discourse, the present talk will elucidate some of the formidable challenges intrinsic to this pursuit and also shed light on the ongoing research endeavors undertaken by my team in the realm of intelligent grasp manipulation. Our objective is to harmonize the intricate symphony of human-robot interactions, bringing us closer to the realization of robots as versatile and discerning collaborators in our everyday lives. |
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