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MEAM Seminar: “Computational Mechanics for Landing on Mars”
October 19, 2021 at 10:00 AM - 11:30 AM
Current technology for decelerating a spacecraft from the high speed of atmospheric entry to the final stages of landing on Mars is based on low-density supersonic decelerators such as low mass and high packaging efficiency parachute systems. To enable future exploration missions featuring sophisticated robots and safely land heavier spacecraft on Mars, larger than before high-speed parachutes and inflatable drag devices are needed. The design, development, and maturing of such devices for future use at Mars require guidance from predictive simulations based on a high-fidelity, multi-disciplinary computational model for parachute inflation dynamics (PID) and drag prediction. The development of such a model is a formidable challenge. It must account for shocks, turbulence, and porous flow boundary conditions; the complexity of the behaviour of fabric material; massive contact between very thin surfaces; and highly nonlinear fluid-structure interactions in the presence of topological changes. The computational model must also be able to predict various instabilities of a parachute such as flutter and pulsation, the influence on its performance of several design factors including material and geometric porosities, and material failure. This lecture will discuss an ongoing effort at Stanford University, in collaboration with NASA Ames and the Jet Propulsion Laboratory, for the development of such a computational model and some associated computational innovations. These include: a multi-scale approach for modeling the dynamics of woven fabrics based on the concept of a locally attached microstructure and mechanics-informed machine learning; a discrete-event-free, spurious-oscillation-free, and total variation diminishing embedded boundary method for multi-material problems; a subgrid scale modeling approach for the treatment of porous wall boundary conditions; and an energy-conserving approach for the discretization of transmission conditions at the interface between fluid and structural representations of disparate spatial dimensions. The lecture will also report on validation results for the simulation of the supersonic inflation dynamics of: the parachute that landed Curiosity on Mars, on August 6, 2012; and those used in NASA’s 2018 ASPIRE tests to help decide which parachute design to use on the recent Mars 2020 mission that landed Perseverance on Mars, on February 18, 2021.
Vivian Church Hoff Professor of Aircraft Structures, and Chairman of the Department of Aeronautics and Astronautics, Stanford University
Charbel Farhat is the Vivian Church Hoff Professor of Aircraft Structures, Chairman of the Department of Aeronautics and Astronautics, and Director of the Stanford-KACST Center of Excellence for Aeronautics and Astronautics at Stanford University. His research interests are in computational engineering sciences for the design and analysis of complex systems in aerospace, mechanical, and naval engineering. He is a Member of the National Academy of Engineering, a Member of the Royal Academy of Engineering (UK), a Doctor Honoris Causa from Ecole Centrale de Nantes, a Doctor Honoris Causa from Ecole Normale Supérieure Paris-Saclay, a designated ISI Highly Cited Author, and a Fellow of AIAA, ASME, IACM, SIAM, USACM, and WIF. He has trained more than 90 PhD and post-doctoral students. For his research on aeroelasticity, aeroacoustic scattering, CFD, dynamic data-driven systems, fluid-structure interaction, high performance computing, and model reduction, he has received many professional and academic distinctions including: the Ashley Award for Aeroelasticity from AIAA; the Spirit of St Louis Medal from ASME; the Gordon Bell Prize from IEEE; the Gauss-Newton Medal from IACM; the Grand Prize from the Japan Society for Computational Engineering Science; and the John von Neumann Medal from USACM. He was appointed on the Scientific Advisory Board of the US Air Force, selected by the US Navy recruiters as a Primary Key-Influencer, and flown by the Blue Angels.