Aerospace Engineering Research Works
Permanent URI for this collectionhttp://hdl.handle.net/1903/1655
Browse
61 results
Search Results
Item Characterization of Magnetorheological Impact Foams in Compression(MDPI, 2024-06-14) Choi, Young; Wereley, Norman M.; Wereley, Norman M.This study focuses on the development and compressive characteristics of magnetorheo- logical elastomeric foam (MREF) as an adaptive cushioning material designed to protect payloads from a broader spectrum of impact loads. The MREF exhibits softness and flexibility under light compressive loads and low strains, yet it becomes rigid in response to higher impact loads and ele- vated strains. The synthesis of MREF involved suspending micron-sized carbonyl Fe particles in an uncured silicone elastomeric foam. A catalyzed addition crosslinking reaction, facilitated by platinum compounds, was employed to create the rapidly setting silicone foam at room temperature, simplify- ing the synthesis process. Isotropic MREF samples with varying Fe particle volume fractions (0%, 2.5%, 5%, 7.5%, and 10%) were prepared to assess the effect of particle concentrations. Quasi-static and dynamic compressive stress tests on the MREF samples placed between two multipole flexible strip magnets were conducted using an Instron servo-hydraulic test machine. The tests provided measurements of magnetic field-sensitive compressive properties, including compression stress, energy absorption capability, complex modulus, and equivalent viscous damping. Furthermore, the experimental investigation also explored the influence of magnet placement directions (0◦ and 90◦) on the compressive properties of the MREFs.Item Adaptive magnetorheological fluid energy absorption systems: a review(Institute of Physics, 2024-03-01) Bai, Xianxu 'Frank'; Zhang, Xinchi; Choi, Young; Shou, Mengje; Zhu, Guanghong; Wereey, Norman M.; Wereley, NormanIn the last two decades, magnetorheological (MR) fluids have attracted extensive attention since they can rapidly and continuously control their rheological characteristics by adjusting an external magnetic field. Because of this feature, MR fluids have been applied to various engineering systems. This paper specifically investigates the application of MR fluids in shock mitigation control systems from the aspects of three key technical components: the basic structural design of MR fluid-based energy absorbers (MREAs), the analytical and dynamical model of MREAs, and the control method of adaptive MR shock mitigation control systems. The current status of MR technology in shock mitigation control is presented and analyzed. Firstly, the fundamental mechanical analysis of MREAs is carried out, followed by the introduction of typical MREA configurations. Based on mechanical analysis of MREAs, the structural optimization of MREAs used in shock mitigation control is discussed. The optimization methods are given from perspectives of the design of piston structures, the layout of electromagnetic coil, and the MR fluid gap. Secondly, the methods of damper modeling for MREAs are presented with and without consideration of the inertia effect. Then both the modeling methods and their characteristics are introduced for representative parametric dynamic models, semi-empirical dynamic models, and non-parametric dynamic models. Finally, the control objectives and requirements of the shock mitigation control systems are analyzed, and the current competitive methods for the ideal ‘soft-landing’ control objectives are reviewed. The typical control methods of MR shock mitigation control systems are discussed, and based on this the evaluation indicators of the control performance are summarized.Item Tailorable Energy Absorbing Cellular Materials via Sintering of Dry Powder Printed Hollow Glass Microspheres(2024-05-01) Wereley, Norman; Park, Jungjin; Howard, John; DeMay, Matthew; Edery, Avi; Wereley, NormanThis article examines amorphous glass-based foams as lightweight core materials for crash-resistant structures that offer tailorable energy absorption capabilities. Hollow glass microspheres (HGMs) of different densities are layered using dry powder printing (DPP), an additive manufacturing process, and subsequently sintered to consolidate these microspheres into a cellular foam structure. The tailoring of energy absorption is achieved in these foams by layering hollow microspheres with different densities and different thickness ratios of the layers. The mechanical response to quasi-static uniaxial compression of the bilayer foams is also investigated. Bilayer samples exhibit a distinctive two-step stress-strain profile that includes first and second plateau stress, as opposed to a single constant density which does not. The strain at which the second plateau occurs can be tailored by adjusting the thickness ratio of the two layers. The resulting stress-strain profiles demonstrate tailorable energy absorption. Tailorability is found to be more significant if the density values of each layer differ greatly. For comparison, bilayer samples are fabricated using epoxy at the interface instead of the co- sintering process. Epoxy-bonded samples show a different mechanical response from the co-sintered sample with a different stress-strain profile. Designing the bilayer foams enables tailoring of the stress-strain profile, so that energy-absorption requirements can be met for a specific impact condition. The implementation of these materials for energy absorption, crashworthiness, and buoyancy applications will be discussed.Item A novel approach to inverse design of wind turbine airfoils using tandem neural networks(Wiley, 2024-05-30) Anand, Apurva; Marepally, Koushik; Safdar, M Muneeb; Baeder, James D.The performance of a wind turbine and its efficiency majorly depends on wind-to-rotor efficiency. The aerodynamic design of the wind turbine blades using high-fidelity tools such as adjoint-computational fluid dynamics (CFD) is accurate but computationally expensive. It becomes impractical when the number of design variables increases for multidisciplinary optimization (MDO). Low-fidelity tools are computationally cheaper but are not accurate, especially in regions of adverse pressure gradient and reverse flows. Surrogate modeling has been used in many aerodynamic problems. We develop and apply a recent architecture of the deep learning module, tandem neural networks (T-NNs) for the inverse design of wind turbine airfoils. The T-NNs trained on CFD data for fully turbulent cases predict not only the performance parameters for the given airfoil geometry but also the airfoil geometry for a given design objective. This framework uses the entire performance polar for inverse design which ensures that the airfoil optimization is not a single-point optimization problem which is essential for practical design problems. The T-NNs are also optimized to include multiple constraints like maximum thickness and trailing edge (TE) thickness which is a novel contribution in the field of inverse design using surrogate models. A statistical analysis is also performed to predict a family of airfoil geometries.Item System identification for high-performance UAV control in wind(Wiley, 2023-08-14) Shastry, Animesh K.; Paley, Derek A.This article describes and experimentally evaluates a comprehensive system identification framework for high-performance UAV control in wind. The framework incorporates both linear offline and nonlinear online methods to estimate model parameters in support of a nonlinear model-based control implementation. Inertial parameters of the UAV are estimated using a frequency-domain linear system identification program by incorporating control data obtained from motor-speed sensing along with state estimates from an automated frequency sweep maneuver. The drag-force coefficients and external wind are estimated recursively in flight with a square-root unscented Kalman filter. A custom flight controller is developed to handle the computational demand of the online estimation and control. Flight experiments illustrate the nonlinear controller's tracking performance and enhanced gust rejection capability.Item Terrapin Rocket Team's Technical Report to the 2023 Spaceport America Cup(2023) Daniel, Hailu; Bean, Andrew; Bregin, Ezra; Gill, Dasam; Roy, Nathan; M Jaffar, Mohamed Khalid; Alessandrini, Garret; Mallamaci, Michael; Goldberg, Adin; Zheng, Howard; Rizvi, SaimThis document presents the University of Maryland’s 10,000 ft SRAD Motor Category rocket, Karkinos. It is the third time that the team will be attending the Cup in person since 2018, and the current team has built on the lessons learned at the 2022 Cup. The design process for Karkinos is centered around manufacturability and reliability coupled with a rigorous testing process. This report also documents the design of our Air Brake system that actively trims the rocket’s altitude during flight. The CubeSat payload for this rocket will test the release of a vehicle from the rocket during drogue descent.Item Simulation of packet dropouts over wireless channels considering Rayleigh fading effects(2020) M Jaffar, Mohamed Khalid; Otte, MichaelThis document describes how we implement a Rayleigh fading model for use in a multi-robot communication simulation. The main objective of this work is to characterize communication losses in multi-agent settings that require high levels of collaboration.Item Feedback motion replanning during high-stakes scenario(2019) M Jaffar, Mohamed Khalid; Otte, MichaelThis paper proposes a novel algorithm for a quadrotor to replan its motion in the event of one, two or three rotor loss. Further, during the course of its replanned trajectory, the MAV avoids collision with static obstacles including the ground.Item Terrapin Rocket Team's Technical Report to the 2022 Spaceport America Cup(2022) Bregin, Ezra; Bean, Andrew; Daniel, Hailu; Roy, Nathan; M Jaffar, Mohamed Khalid; Alessandrini, Garret; Mallamaci, Michael; Goldberg, Adin; Zheng, Howard; Gill, DasamThis document presents University of Maryland’s 10,000 ft COTS Motor Category rocket, Terpulence II. This project is a return to high power rocketry fundamentals within the Terrapin Rocket Team. It is the first time that the team will be attending the Cup in person since 2018 and the first time any current team members will compete at Spaceport. The design process is targeted at building off of other successful projects and manufacturing a safe and reliable competition rocket. This reports also documents the design of a novel air brake system that increases the rocket performance to reach a desired apogee. The CubeSat payload for this rocket will test liquid fuel tank geometry to gauge if capillary action can replace ullage motors in micro-gravity environments.Item Magnetic Susceptibility Instrument for Magnetically Inhomogeneous Granular Mixtures(Review of Scientific Instruments, 2024) Charles T. PettWe introduce an instrument and novel method for characterizing the bulk magnetic susceptibility of granular mixtures by submerging an inductor coil in a bed of metallic beads and gauging changes in self-inductance. The resonance frequency of the coil was measured to determine its inductance and evaluate the magnetic permeability of ferrous mixtures relative to air. In air, our coil was accurate to within 3% of the permeability of free space. The range of magnetic susceptibility values for magnetically inhomogeneous granular mixtures is poorly constrained, but our coil uniquely quantifies bulk effects that other surface meters are not designed to resolve. Compared to both a commercial Terraplus Inc. KT-10 meter and theoretical approximations, we report similar trends in susceptibility values measured as a function of mass of ferromagnetic material per volume.