AE Research Publications

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    Effects of manufacturing defects on composite seat pans at static and dynamic strain rates
    (American Institute of Aeronautics and Astronautics Inc, AIAA, 2024) Bhasin, Akhil; Maichan, Tanat; Gomez, Luis M.; Olivares, Gerardo; Keshavanarayana, Suresh R.
    The use of composite materials in aircraft primary seat structures has increased and requires additional standards to maintain the current level of aircraft seat safety. The presence of manufacturing defects or service damage could undermine the load-carrying capabilities of these structures at dynamic loading rates. In the current work, the effects of out-of-plane fiber waviness/wrinkle on representative aircraft seatpans has been investigated. The seatpans are tested at both quasi-static and elevated strain rates. The performance of seatpans with defects is compared against pristine seatpans. All the experiments were conducted using a high-rate test frame and were supported with high-speed Digital Image Correlation (DIC). A comparison of load, displacement, strain, and strain rate at failure between different configurations is reported. © 2024 by Akhil Bhasin, NIAR AVET.
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    Designing hybrid aerogel-3D printed absorbers for simultaneous low frequency and broadband noise control
    (Elsevier Ltd, 2024) Xue, Yutong; Nobles, Laura Paige; Sharma, Bhisham N.; Bolton, J. Stuart
    Recent studies have demonstrated that granular aerogels with sub-50 ?m particles surpass conventional acoustic materials like glass fibers and polyurethane foams in low-frequency sound absorption. However, incorporating such granular materials within practical structural solutions remains a challenge. In this study, we use additive manufacturing to overcome this challenge by designing a modular geometry that allows us to encapsulate such granular materials within a 3D printed scaffold. Using the 3D printed porous scaffold provides the added benefits of tunability and durability. Further, we introduce a design methodology and software tool to facilitate the efficient design of such hybrid sound absorbers. The proposed method uses the Johnson-Champoux-Allard model, Biot theory, and the transfer matrix method to model the acoustical behavior of hybrid absorber designs that use layered granular aerogels and 3D printed bulk absorbers. The tool can also be used to inversely characterize the acoustic bulk properties of such materials. We validate the design concept and tool by comparing the model predictions with experimental measurements. Finally, we outline strategies for designing hybrid absorbers that can provide application specific low-frequency and broadband absorption performance within specific frequency ranges, while considering engineering constraints on their total mass and depth. © 2024 The Author(s)
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    Vortex shedding from bluff bodies: a conformal mapping approach
    (Springer Science and Business Media B.V., 2024) Matheswaran, Vijay; DeLillo, Thomas K.; Miller, L. Scott
    A model to calculate flow around bluff bodies of various geometries is presented. A conformal map between the plane of the bluff body and the plane of a unit circular cylinder is established by using a combination of Karman-Trefftz transformations and Fornberg's method. Flow in the circle plane is calculated using the authors' Hybrid Potential Flow (HPF) model and mapped back to the shape plane. By joining this calculated near-body flow with von Karman's model for a vortex wake, forces due to vortex shedding and shedding frequencies are calculated. In this manner, a complete solution for the flow around bluff bodies of various geometries is established. Results for two shapes are presented, along with recommendations for further work. © The Author(s) 2024.
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    Programming quantum hardware via Levenberg- Marquardt machine learning
    (CRC Press, 2024) Steck, James E.; Thompson, Nathan L.; Behrman, Elizabeth C.
    We present an improved method for quantum machine learning, using a modified Levenberg-Marquardt (LM) method. The LM method is a powerful hybrid gradient-based reinforcement learning technique ideally suited to quantum machine learning, as it only requires knowledge of the final measured output of the quantum computation, not intermediate quantum states, which are generally not accessible without collapsing the quantum state. With this method, we are able to achieve true online training of a quantum system to do a quantum calculation, which, to our knowledge, has never been done before. We demonstrate this using a fundamentally non-classical calculation: estimating the entanglement of an unknown quantum state. Machine learning is applied to learn this algorithm and is demonstrated in simulation and hardware. We show results for two-, three-, four-, five-, six-, seven-, and eight-qubit systems, in Matlab simulations, and, more importantly, these run on the IBM Qiskit hardware interface. With this approach, the quantum system, in a sense, designs its own algorithm. Moreover, the approach enables scaleup, is potentially more efficient, and provides robustness to both noise and decoherence. � 2024 selection and editorial matter, Siddhartha Bhattacharyya, Iv�n Cruz-Aceves, Arpan Deyasi, Pampa Debnath, and Rajarshi Mahapatra; individual chapters, the contributors.
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    Neuro-adaptive Model Reference Tracking Controller for Cislunar Missions
    (American Institute of Aeronautics and Astronautics Inc, AIAA, 2024) Pillay, Yrithu; Chace, Matthew; Steck, James E.; Watkins, John Michael; Dutta, Atri
    A neuro-adaptive observer, Modified State Observer (MSO), is combined with a Non-Linear Dynamic Inversion (NDI) controller to provide correction thrusts for a low-thrust spacecraft in cislunar space. The MSO helps capture the system modeling error and non-linear uncertainties of the environment while the NDI controller provides a control law that is control affine. A target reference trajectory ending at a lunar Near-Linear Rectilinear Halo Orbit (NRHO) insertion point with continuous thrust is used to study the effectiveness of the controller. A high-fidelity model is created incorporating the lunar ephemeris to represent the true three-body spacecraft model. The effectiveness of the control law in providing reference tracking in this problem is studied. Moreover, the tests are extended to a case where the true dynamics are available, but a Missed Thrust Event causes the thrust along a direction to cut off. © 2024 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.