21-30 of 35 results
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Behavior of superalloys subjected to fatigue loads under high temperature
PI Alberto Mello
CO-I Paulina De La Torre Morales
CO-I Open Position - New students are welcome
This study is evaluating what initial conditions can activate cubic slip planes, then the level of accommodation and strain homogenization within the grain, and how a given initial condition affects the material behavior when subjected to operational cyclic loads under high temperature.
Ni-based super alloys are widely used in turbine engines mainly due to its high strength and fatigue resistance at elevated temperatures. One hypothesis to explain its atypical characteristic among metals is that a cross-slip mechanism is in place. The activation of {100} cubic slip systems along of the octahedral slip planes {111} in Ni-based superalloys has been verified when under high strain and temperature. The material would exhibit a more homogeneous strain distribution and less strain localization. We seek for the ideal precondition that will improve the endurance of Ni-based superalloy (IN 718) samples subjected to operational loading. We evaluate the initial conditions that activate cubic slip planes, the level of accommodation, and strain homogenization within the grain. With focus on the deformation mechanism, the sample microstructure can be fully characterized by electron backscatter diffraction (EBSD) and the slip systems, after the applied pre-condition, can be tracked via digital image correlation (DIC).
Accomplished tasks:
(a) samples’ manufacturing, (b) sample polishing and preparation, (c) furnace installation and operational tests, (d) development of laboratory procedures, equipment and microscopes (optical and SEM), (d) calibration and controller fine tuning for the MTS tensile testing machine, and (e) fatigue test with several specimens, including control samples and modified pre-conditions
Next steps:
Characterization of the microstructure of tested specimens under special conditions via EBSD to identify the slip planes and confirm or not the activation of cubic slip systems.
Categories: Faculty-Staff
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Influence of cold expansion and aggressive environment on crack growth in aluminum alloy
PI Alberto Mello
CO-I Christopher Leirer
CO-I Ken Shishino
CO-I Open Position - New students are welcome
This research aims to establish the effect of hole cold expansion on fatigue life of pre-cracked material under aggressive environment.
This research investigates the relationship between crack propagation and secondary crack initiation in aluminum alloys with cold worked holes subjected to cyclic loads to determine the impact on fatigue life of joints in presence of aggressive environment. We work with experiments and analysis of fatigue life of bolted joints with coldworked holes in presence of galvanic corrosion. This investigation is examining the effect of local plastic deformation and localized galvanic corrosion on small cracks and fatigue life of bolted joints. The benefits of cold work are well known and its application is widely used in new and repaired structures, even in crack arrester holes. However, coldworked holes are usually fastened to dissimilar materials, what may induce localized galvanic corrosion. When applied in the field, damaged material removal in a cold work procedure may be limited to a maximum allowable diameter for reaming and finishing, what may leave micro/small cracks on the strained region. To completely understand the effect of initial cracks as a function of initial plastic deformation level in a coldworked hole it is necessary to fully evaluate strain distribution during and post cold work with microscopic detail. In a first approach, we have analyzed (FEM and classic analysis) and measured strain distribution during the process using digital image correlation (DIC). In the next step, we have tested specimens under fatigue. Pre cold work induced micro cracks was monitored in-situ via digital optical microscopy. In sequence, the coldworked holes were filled with a dissimilar material fastener in saline environment and the impact of galvanic corrosion on crack growth rate was determined for AA 2024-T3.
In a next step, we will further investigate the formation of critical secondary cracks. The probable cause could be a local corrosion around cathodic precipitates, but a detailed study is necessary to confirm this hypothesis. The tested samples must be prepared for use in scanning electron microscope (SEM) to identify the local pit formation at the plate edge, find the point of crack initiation, and determine the propagation path. Using striation counting technique, we may be able to estimate the number of cycles to failure and, consequently, the time necessary for the crack initiation under aggressive environment. Additionally, we will plan to use and analyze a special ceramic coating to mitigate galvanic corrosion effect on loaded components.
Categories: Graduate
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Bird Strike - The Effect of the Leading Edge Radius on the Behavior of the Bird Upon Impact
PI Alberto Mello
CO-I Kiran Kumar Avula
CO-I James Pembridge
This project is in partnership with Gulfstream Aerospace Corporation under MMSE program.
Birds pose a major threat to aviation. Bird impact can lead to significant damage of the aircraft and can be sometimes catastrophic. For a damage tolerant design of an aircraft structure, the structure has to fulfill the airworthiness specifications prescribed by FAA or EASA.
According to FAR 25, Sub-part 25.571, leading-edge structures of large transport aircraft have to withstand an impact with a 4 lb (1.81 kg) bird (8 lb (3.62kg) for empennage leading edge) when the velocity of the airplane relative to the bird along the airplane's flight path is equal to its cruising speed (Vc) at sea level or 0.85 (Vc) at 8,000 feet, whichever is more critical.
When a bird impacts the structure, it either slides off of the impacted surface causing less damage or it creates a dent or hole due to penetration into the structure, causing significant damage. The behavior of the bird upon the impact depends on the geometrical characteristics of the structure and the velocity at which the bird impacts. When split upon impact, it results in low impact forces and thus less damage. The impact forces are higher when the bird doesn’t split upon the impact which causes more damage to the target structure as the impact forces are directly proportional to the mass of the bird.
Bird strike tests are very expensive and their number in the engine development programs should be minimized. Numerical simulations help reduce a significant amount of testing by providing valuable information in the design process. This thesis aims to develop a model using smooth particle hydrodynamics (SPH) method for analyzing aircraft leading edges for bird strikes that will correlate well with the test results and subsequently, apply the method to study the effect of the leading edge radius on the behavior of the bird (split/not split) upon the impact.
The objective is to generate sufficient data through numerical analysis to confirm the “one inch radius split/no split dividing line”, and to validate the empirical formulas used to calculate the impact forces. Overall, the goal is to save both time and money for the future generation aircraft by minimizing or eliminating the bird strike tests.
Categories: Graduate
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Pilot-in-the-Loop UAS Mobile Research Test-Bed
PI Hever Moncayo
CO-I May Chan
CO-I Ashwini Agrawal
CO-I Agustin Giovagnoli
This project aims to develop and implement a Mobile UAV Ground Control Station (GCS) supporting aviation safety research with pilot-in-the-loop capabilities using unmanned aerial systems platforms, in which flight conditions, such as systems failures, could be simulated in real-time to characterize pilot response, control laws performance, and human-machine and control laws interactions.
A fruitful achievement of this project will provide a platform to validate and assess new concepts and technologies that are beneficial for improving engineering fidelity of early systems integration testing based on pilots feedback and their interaction with on-board flight controls systems.
Categories: Faculty-Staff
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Shielded UAS Operations Detect and Avoid
PI Hever Moncayo
This effort is intended to identify risks and recommend solutions to the FAA that enable shielded UAS operations
This project is funded under the FAA ASSURE program. Certain small UAS (sUAS) Beyond Visual Line of Sight (BVLOS) operations, such as structural inspection, may be in close proximity to structures that are collision hazards for manned aircraft. These types of operations that are in close proximity to manned aviation flight obstacles such that they provide significant protection from conflicts and collisions with manned aircraft are termed “shielded” operations. This effort is intended to identify risks and recommend solutions to the FAA that enable shielded UAS operations. Several topics related to this project include simulation of dynamic systems, simulation environment programming, guidance, control and dynamics, and hardware implementation.Categories: Faculty-Staff
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Vision and Wireless-Based Surveying for Intelligent OSAM Navigation (VISION)
PI Hever Moncayo
CO-I Kadriye Merve Dogan
In this project, which is a SpaceWERX Phase I STTR program with Orbital Prime, we are developing algorithms to increase autonomy of OSAM applications.
In this project, which is a SpaceWERX Phase I STTR program with Orbital Prime, we are developing algorithms to increase autonomy of OSAM applications. This includes the application of machine learning techniques to improve accuracy of position and orientation estimation for proximity operations in space. Machine learning include deep learning combined with vision-based navigation designed and tested in both, virtual simulation environment and actual thrust-based spacecraft system.
Categories: Faculty-Staff
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Mitigating GPS and ADS-B Risks for UAS
PI Hever Moncayo
In this project, the research team is investigating different strategies to mitigate such risks and proposing methodologies to increase safety of UAS operations within the National Airspace.
This project is funded under the FAA ASSURE program. Unvalidated or unavailable GPS and “ADS-B In” data poses security and safety risks to automated UAS navigation and to Detect and Avoid operations. Erroneous, spoofed, jammed or dropouts of GPS data may result in unmanned aircraft position and navigation being incorrect. This may result in a fly away beyond radio control, flight into infrastructure or flight into controlled airspace. Erroneous, spoofed, jammed or dropouts of “ADSB-In” data may result in automated unmanned aircraft being unable to detect and avoid other aircraft or result in detecting and avoiding illusionary aircraft.
In this project, the research team is investigating different strategies to mitigate such risks and proposing methodologies to increase safety of UAS operations within the National Airspace. Several topics related to this project include simulation of dynamic systems, artificial intelligence, flight testing of UAS and hardware implementation.
Categories: Faculty-Staff
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Experimental Testbed for the Validation of Autonomous ISAM/OSAM Systems
PI Morad Nazari
CO-I Kadriye Merve Dogan
CO-I Thomas Lovell
The ability to validate individual hardware and software components of these technologies on a large scale is still in its early stages. Thus, the goal of this research is to establish an effective experimental testbed for the validation of autonomous in-space servicing and maintenance (ISAM) / on-orbit servicing and maintenance (OSAM) systems.
A new era of affordable space flight, satellite refueling, on-orbit inspection, orbit transfer and end-of-life servicing has begun as a result of the space industry's continued focus on safe, resilient and adaptable space vehicles. These developments have laid the groundwork for assembly and manufacturing in orbit or space for potential use in active debris removal, reuse and recycling of materials. Advanced navigation and control technologies are required to ensure and lengthen the mission life cycles of these orbital assets, which include launch vehicles, satellites and space stations. Orbit/attitude determination, relative motion, robot manipulator kinematics and spacecraft rendezvous/docking can benefit from new advances in geometric mechanics Udwadia-Kalaba, adaptive control, learning, sensor fusion, computer vision and data communication. These efforts aim to equip future enterprises with the ability to perform in-space servicing and maintenance (ISAM) and on-orbit servicing and maintenance (OSAM) of failed or damaged space assets, as well as in-space manufacturing and platform assembly. However, the ability to validate individual hardware and software components of these technologies on a large scale is still in its early stages. Thus, the goal of this research is to establish an effective experimental testbed for the validation of autonomous ISAM/OSAM systems.Categories: Faculty-Staff
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Flexible Body Control Using Fiber Optic Sensors, Florida Space Grant Consortium
PI Morad Nazari
CO-I Daewon Kim
This project would build on previous research that developed the dynamics formulation and control of a rigid-flexible system.
This project would build on previous research that developed the dynamics formulation and control of a rigid-flexible system. A cantilevered beam attached to a rotating central body is considered and analyzed through the finite element method. A set of matrix differential equations are obtained to describe the dynamic behavior of the system, and a control law based on a Lyapunov function is obtained and applied to the system. The development of this dynamics formulation and control also considers the rigid-flexible coupling present in the system. The control law is designed such that the system can achieve and maintain a set of desired states for the central rigid body and flexible structure. The experimental measurements obtained from the implementation of FOS sensors on the flexible body and inertial sensors on the rigid body will be utilized as the input in this control design. The research portion of the project is anticipated to require one or two graduate student research assistants and a part-time academic advisor over a one-year period.
Categories: Faculty-Staff
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Reconfigurable Guidance and Control Systems for Emerging On-Orbit Servicing, Assembly and Manufacturing (OSAM) Space Vehicles
PI Morad Nazari
CO-I Kadriye Merve Dogan
In this project, the ControlX team with ERAU partnership will develop agile, reconfigurable, and resilient dynamics and G&C algorithms for on-orbit servicing to capture a broad set of OSAM applications such as remediation of resident space object (RSO) (e.g., via de-orbiting, recycle, end-of-life servicing, satellite refueling, etc.) using effective tools and methods involving geometric mechanics, constrained G&C synthesis, and reconfigurable robotic manipulators (RRMs).
Dynamic response to emergent situations is a necessity in the on-orbit servicing, assembly and manufacturing (OSAM) field because traditional on-orbit guidance and control (G&C) cannot respond efficiently and effectively to such dynamic situations (i.e., they are based on either constant mass or diagonal matrix of inertia). In these circumstances, the current challenge is to develop modeling strategies and control systems that exhibit intelligence, robustness and adaptation to the environment changes and disturbances (e.g., uncertainties, constraints and flexible dynamics). Note that the current state-of-the-art methods do not offer a reliable, accurate framework for real-time, optimal accommodation of constraints in the system dynamics that account for orbital-attitude coupling in the motion of the bodies without encountering singularity or non-uniqueness issues. In this project, the ControlX team with ERAU partnership will develop agile, reconfigurable, and resilient dynamics and G&C algorithms for on-orbit servicing to capture a broad set of OSAM applications such as remediation of resident space object (RSO) (e.g., via de-orbiting, recycle, end-of-life servicing, satellite refueling, etc.) using effective tools and methods involving geometric mechanics, constrained G&C synthesis, and reconfigurable robotic manipulators (RRMs).
The proposed work in this Phase I includes reconfigurable systems for on-orbit servicing, assembly and manufacturing with learning control methods that minimize tracking error of the end-effector of the RRM in the presence of uncertainties, optimize configuration and accommodate constraint-changing scenarios. Our developments will avoid singularity; not rely on the concept of costates or Lagrange multipliers that are restrictive; handle system uncertainties while enforcing the constraints; use RRMs in different tasks (recycle, debris removing, maintenance, etc.); not need in sensors or exact model knowledge for robotic arms. Specifically, constrained space vehicle control (predicated on Udwadia and Kalaba (UK) formalism) will offer not only accurate and resilient design but also reconfigurability in that G&C algorithms can easily be modified to suit a wide spectrum of OSAM applications. ControlX team will also consider the feasibility of hardware implementation. The selection of sensors, actuators and onboard computers will be an important trade-off between among size, weight, and power (SWaP) constraints, reliability, and computing performance. A real-time operating system (RTOS) is planned to meet timing and memory management constraints, partitioning hardware resources to control software application interactions. An analysis suite for the autonomous system implementation, based on system modeling and learning techniques, will provide onboard analysis, enabling decision-making as to whether the system can continue to meet mission requirements.
Categories: Faculty-Staff
21-30 of 35 results