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ASME Aerospace Structures, Structural Dynamics, and Materials Conference > Program > Track Keynote Speakers

Track Keynote Speakers

Dr. Samit Roy

Dr. Samit Roy
The University of Alabama

Presentation Title: Atomistic Simulation of Damage in Carbon-Carbon Composites from Impact with Water Droplets at Hypersonic Velocity

Abstract: Carbon-carbon (C-C) composites used in hypersonic airframes experience extreme thermo-mechanical stresses and environmental conditions that can lead to physical and chemical erosion of the material. The leading-edge of a hypersonic airframe may undergo erosion due to extreme aerodynamic heating and entrained moisture in the boundary layer. Such leading-edge erosion could adversely affect the accuracy of the terminal guidance to target of a hypersonic weapon. This study employs reactive molecular dynamics (RMD) to simulate the impact of water droplets on a novel C-C composite at hypersonic velocity transiting through a shockwave prior to impact. The composite consists of simulated carbon fibers embedded within a glassy carbon matrix derived from the pyrolysis of polyfurfuryl alcohol (PFA), modeled using ReaxFF potential. The polymerization and pyrolysis processes are precisely modeled using RMD simulations, closely matching experimental findings. To emulate the realistic flight environment, the simulation incorporates a pre-formed air shock-wave layer through which the water droplet travels before striking the heated composite surface at hypersonic velocity results in material degradation due to impact as well as chemical ablation due to high-temperature (2500 K) oxidation. This approach enables the evaluation of mechanical damage as well as chemical degradation in C-C composites, an aspect often neglected in purely mechanical simulations like finite element analysis or peridynamics. Figure 1 shows the RMD predicted damage on a simulated C-C composite due to water droplet impact normal to the surface and oblique to the surface. As shown in the figure, the depth of the crater due to oblique impact is less severe than the direct impact case. Furthermore, the flattening of the water droplet while transiting through the shock-wave region prior to impact on the C-C composite results in less severe cratering. The insights gained here are critical for advancing predictive models of erosion on C-C composites and guiding the design of next-generation thermal protection materials for hypersonic aerospace applications.

Biography: Dr. Samit Roy received his Ph.D. in Engineering Science & Mechanics from Virginia Tech in Blacksburg, Virginia. He is currently the William D. Jordan Endowed Professor in the Department of Aerospace Engineering and Mechanics at University of Alabama (UA). Dr. Roy's research interest is directed towards multi-scale modeling and life-prediction of fiber reinforced polymer composites and structural adhesives subjected to aggressive environmental conditions. He is also actively involved in the application of nanostructured reinforcements in enhancing performance of composite materials, and was awarded a patent for this work in 2023. He has developed structural health management concepts that include sensor placement optimization for structural weight and cost reduction, as well as smart materials for intelligent self-healing. This research has attracted keen interest from the US Air Force and NASA and he has filed for a provisional patent related to this work. He has authored over 200 peer-reviewed journal articles and book chapters, and has monitored more than 25 graduate students at UA. He was elected Associate Fellow of the American Institute of Aeronautics and Astronautics (AIAA) in 2004, elected Fellow of ASME in 2010, and Fellow of American Society for Composites (ASC) in 2022. He was elected Chairman of the ASME NanoEngineering for Energy and Sustainability (NEES) steering committee in 2014, and is the current Division Chair, Emerging Composite Technologies Technical Division, of the American Society for Composites since 2022. He is the recipient of the ASC Outstanding Researcher Award in Composites in 2019 and again in 2023.

Joaquim R. R. A. Martins

Joaquim R. R. A. Martins
University of Michigan

Presentation Title: Shaping Next-Generation Aircraft with Multidisciplinary Design Optimization

Abstract: Air transportation's quest for efficiency requires groundbreaking advancements in aircraft design, particularly in the optimization of aircraft configurations, including aerodynamic shape, structural sizing, and propulsive performance. This talk will examine the latest developments in computational fluid dynamics (CFD)-based design optimization, addressing the critical challenges and innovative solutions in shaping aircraft components for enhanced efficiency and reduced emissions. We will explore the integration of CFD with structural mechanics to optimize wing aerodynamics, enhance lift-to-drag ratio, and reduce structural weight. The discussion will extend to the aerodynamic optimization of propellers and turbofans, highlighting how CFD facilitates the design of propulsion systems that integrate optimally with the airframe. By employing multidisciplinary optimization (MDO) approaches, we have advanced the design of these key aircraft components, considering complex interactions and design constraints. We will focus on the adjoint method for efficient gradient computation, which is essential for handling the large number of shape and sizing variables required in aircraft design. The talk will present case studies demonstrating the successful application of these methods in optimizing aircraft wings, along with innovative designs of propellers and turbofans. Finally, we will discuss our vision for using MDO to shape the future of sustainable aviation.

Biography: Joaquim R. R. A. Martins is the Pauline M. Sherman Collegiate Professor of Aerospace Engineering at the University of Michigan, where he heads the Multidisciplinary Design Optimization Laboratory. His research group develops MDO methods and applies them to the design of air and marine vehicles, as well as other engineering systems. He is a co-author of “Engineering Design Optimization”, a textbook published by Cambridge University Press. Prof. Martins is a Fellow of the American Institute of Aeronautics and Astronautics and a Fellow of the Royal Aeronautical Society. Before joining the University of Michigan faculty in 2009, he was an Associate Professor at the University of Toronto Institute for Aerospace Studies. From 2002, he held a Tier II Canada Research Chair in Multidisciplinary Optimization. He received his undergraduate degree in Aeronautical Engineering from Imperial College, London, with a British Aerospace Award. He obtained his M.Sc. and Ph.D. degrees from Stanford University, where he was awarded the Ballhaus prize for best thesis in the Department of Aeronautics and Astronautics. He has received the Best Paper Award at AIAA Conferences six times. He has served as Associate Editor for the AIAA Journal, Optimization and Engineering, and Structural and Multidisciplinary Optimization. He is currently an Associate Editor for the Journal of Aircraft.

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