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X-ORIGINAL-URL:https://aero.iisc.ac.in
X-WR-CALDESC:Events for Department of Aerospace Engineering
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TZID:Asia/Kolkata
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TZOFFSETFROM:+0530
TZOFFSETTO:+0530
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DTSTART:20240101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240614T160000
DTEND;TZID=Asia/Kolkata:20240614T170000
DTSTAMP:20260517T135244
CREATED:20240614T061338Z
LAST-MODIFIED:20240803T061531Z
UID:10000015-1718380800-1718384400@aero.iisc.ac.in
SUMMARY:Design and characterization of periodic scatterers for noise insulation
DESCRIPTION:The array of periodic scatterers is known as sonic crystal at present and sonic crystal is the most cost-effective solution for a “noise barrier” because of its acoustic attenuation due to size\, geometry\, and periodic arrangement of scatterers. Porous materials that are commonly used for sound absorption have poor sound insulation capability. In this work\, rigid scatterers are installed periodically inside porous materials to improve their transmission loss (TL) with the Bragg diffraction. The Delany-Bazley impedance model is used to model the porous material and the transfer matrix method is adopted to calculate the TL of the mixed structure in a duct. Simulation results with a different number of scatterers and porous materials with different airflow resistivity show that the TL of porous materials can be increased significantly with periodically arranged scatterers. The decoupled analysis reveals that the TL of the mixed structure is larger than the sum of the TL of individual components in most frequency bands\, except that around the first Bragg resonance frequency. Afterwards\, the insertion loss (IL) of two types of finite size structures constructed by installing two parallel porous sheets within rows of periodic scatterers is investigated in free field. Next\, the free field insertion loss (IL) and echo reduction (ER) are calculated for finite size periodic scatterers via time domain simulations in a room environment where the walls of the room are acoustically reflective. A spectrally dense short pulse is used as a sound source and the time domain pulse separation technique is devised to calculate the IL and ER of finite size periodic scatterers. The key discovery of the research is that the calculated IL and ER of periodic cylindrical scatterers in a room environment agree to results obtained from the free field simulations which are also imitable experimentally. Next\, the experiments are conducted in a room environment with periodic cylindrical scatterers. A loudspeaker is used as a sound source. The signal synthesis technique is demonstrated to generate the desired short pulse from a loudspeaker for measurement in given environment followed by measurements which agree to simulation results. \n  \nSpeaker: Dr. Dibya Prakash Jena \nBiography: Dr. Dibya Prakash Jena is an expert in artificial metamaterials\, condition monitoring\, and acoustics\, vibration and noise control having wide experience in industry and academia. He has been awarded the DIN Young Visiting Fellowship 2022 and the Honorary Research Fellow of the University of Technology Sydney. He has over 32 journal publications\, 4 patents\, 2 book chapters and 12 conference publications.
URL:https://aero.iisc.ac.in/event/design-and-characterization-of-periodic-scatterers-for-noise-insulation/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:AE Seminar
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/AE-Seminar.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240624T110000
DTEND;TZID=Asia/Kolkata:20240624T120000
DTSTAMP:20260517T135244
CREATED:20240624T052703Z
LAST-MODIFIED:20240803T060320Z
UID:10000008-1719226800-1719230400@aero.iisc.ac.in
SUMMARY:[PhD Colloquium] Effect of Interface Roughness in Adhesively Bonded CFRP Joints – Experimental and Numerical Studies
DESCRIPTION:This thesis focuses on surface preparation and its effect on the shear strength of adhesively bonded Single Lap Joints (SLJs) in Carbon Fiber Reinforced Polymer (CFRP)\, their fracture properties\, and the associated Non-Destructive Evaluation (NDE) parameters. The surface preparation was carried out using different grades of emery paper so that the interfaces of different roughness were available for bonding. The morphology of the interfaces before bonding was captured with the light interferometry using Micro-System Analyzer. Roughness parameters were characterized by contact-based measurements. The correlations of the contact angle between the droplet of liquid and the bonding interface with varied surface roughness and the increase in area with respect to the smoothest surface were established. CFRP\, one of the most preferred composite materials in the aerospace industry\, has been chosen in this study. A band of NDE techniques was utilized to evaluate the effects of surface roughness in Adhesively Bonded Joints(ABJs) of CFRP adherends. This included Ultrasonic Testing (UT)\, Infra-Red Thermography (IRT)\, Acoustic Wave Propagation (AWP)\, Acoustic Emission Testing (AET)\, X-ray Radiography Testing (XRT)\, and Digital Image Correlation (DIC). The primary objective of evaluating the effect of interface surface roughness on the strength of adhesively bonded composites has been addressed adequately\, which has yielded very significant\, interesting and effective outcome. Further research along the same line can help in developing an effective and important NDE tool for health monitoring of adhesively bonded joints. \nSpeaker: MANE LAXMIKANT SARJERAO
URL:https://aero.iisc.ac.in/event/effect-of-interface-roughness-in-adhesively-bonded-cfrp-joints-experimental-and-numerical-studies/
LOCATION:AE 105
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/Thesis-Colloquium-Defence.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240627T153000
DTEND;TZID=Asia/Kolkata:20240627T163000
DTSTAMP:20260517T135244
CREATED:20240626T053743Z
LAST-MODIFIED:20240803T060237Z
UID:10000009-1719502200-1719505800@aero.iisc.ac.in
SUMMARY:[MTech(Res) Colloquium] Inflatable aerodynamic decelerators for atmospheric re-entry
DESCRIPTION:Atmospheric re-entry is the most challenging part of human space flight. In the re-entry phase of flight\, the crew module (or re-entry vehicle) is required to bring the onboard astronauts from orbital velocities\, which are in the range of several kilometers per second\, to near-zero velocity at touchdown\, in a safe and controlled manner. The crew module experiences severe aerodynamic heating and large deceleration loads (g-forces) as it descends into the atmosphere at high hypersonic velocities. Re-entry poses formidable engineering challenges\, and also places great physical and mental demands on astronauts.\n\nThe re-entry crew module of the Gaganyaan space program follows a positive L/D (aerodynamic lift to drag ratio) descent trajectory that is established through an offset CG (center of gravity) design. Reaction thrusters provide roll\, pitch\, and yaw control. The design and philosophy of the Gaganyaan crew module is similar to that of the Soyuz crew module. However\, the Soyuz crew module additionally incorporates a ballistic descent mode for use during off-nominal (emergency) situations. Ballistic descent requires a zero L/D condition\, which is achieved by Soyuz through a continuous rotation of the crew module at the rate of 13 degrees per second. The Gaganyaan crew module does not presently incorporate such a feature.\n\nThe present effort is aimed at developing the concept of inflatable aerodynamic decelerators (IADs) to achieve standby ballistic mode capability\, and to also reduce deceleration and aerodynamic heating loads during routine re-entry (or entry to other planetary atmospheres). The aerodynamic characteristics of a canonical re-entry body – crew module with an IAD – at hypersonic Mach numbers is studied through flow computations (using Reynolds-averaged Navier–Stokes equations) and wind tunnel experiments. The L/D of the re-entry body is varied by changing its CG location\, which is achieved by altering the relative position of the IAD with respect to the crew module. The default re-entry body configuration is set for a positive L/D\, which significantly limits deceleration and aerodynamic heating loads. The L/D is brought to zero to achieve ballistic re-entry in an off-nominal situation. Using the aerodynamic data obtained from flow computations and experiments\, the advantages of using an IAD for re-entry are quantitatively assessed and demonstrated through trajectory analysis. A preliminary engineering feasibility study for the proposed concept is also presented in this thesis.\n\nSpeaker: Gp. Capt. Prasanth Balakrishnan Nair (ISRO Human Space Flight Centre)
URL:https://aero.iisc.ac.in/event/mtechres-colloquium-inflatable-aerodynamic-decelerators-for-atmospheric-re-entry/
LOCATION:AE Auditorium
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/Thesis-Colloquium-Defence.jpg
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240627T153000
DTEND;TZID=Asia/Kolkata:20240627T163000
DTSTAMP:20260517T135244
CREATED:20240627T053941Z
LAST-MODIFIED:20240803T060152Z
UID:10000010-1719502200-1719505800@aero.iisc.ac.in
SUMMARY:[MTech(Res) Colloquium] Sub-mesoscale modeling of woven fabrics using VAM-based geometrically-exact beam model
DESCRIPTION:In this work\, a sub-mesoscale model of a woven fabric is developed using finite element methods. The yarns are modeled as beam elements that move freely in space and undergo large deformations and rotations. The geometrically-exact beam theory (GEBT) used to model composite beams of arbitrary cross sections is considered to model the yarns. The variational asymptotic method (VAM) offers the advantage of modeling beams of arbitrary cross sections. A surface-to-surface contact model is developed\, considering that the contact occurs at a point on the surface. The robustness of the contact model is tested by designing a patch test. The mesoscale model is validated using experimental results of biaxial tests performed on a plain glass weave woven fabric. The biaxial simulation is performed by varying the number of yarns in the mesoscale model to study the behavior of the model and demonstrate a representative volume element (RVE). The yarns are made up of fibers twisted together. An isotropic model is an approximation that works well on the mesoscale\, but a more general model is needed to include fiber-level information. Most microscale models use technologically expensive micro-CT scans. There are powerful homogenization techniques\, such as variational asymptotic homogenization (VAH)\, that can be leveraged to develop homogenized properties of the yarn by including fiber-level information. The use of VAH includes more physics into the model with minimal effort. A novel alternative model to a woven fabric is developed using VAM to include microscale information. The tools like cross-sectional analysis\, GEBT\, and VAH are used to study the behavior of woven fabrics with different coatings. The model can be extended by introducing friction between yarns in the contact. Further\, the uncertainty in the input parameters can be quantified by propagating the uncertainty through the system using uncertainty quantification (UQ) techniques. \n  \n\nSpeaker: R ADHITHYA
URL:https://aero.iisc.ac.in/event/mtechres-colloquium-sub-mesoscale-modeling-of-woven-fabrics-using-vam-based-geometrically-exact-beam-model/
LOCATION:STC Seminar Hall\, Dept. of Aerospace Engineering
CATEGORIES:Thesis Colloquium / Defence
ATTACH;FMTTYPE=image/jpeg:https://aero.iisc.ac.in/wp-content/uploads/2024/04/Thesis-Colloquium-Defence.jpg
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