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TZID:Asia/Kolkata
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TZOFFSETFROM:+0530
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DTSTART:20240101T000000
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BEGIN:VEVENT
DTSTART;TZID=Asia/Kolkata:20240627T153000
DTEND;TZID=Asia/Kolkata:20240627T163000
DTSTAMP:20260523T071738
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:20260523T071738
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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