Great Hall: 1:00 – 2:00pm
Poster presentations are a great way to learn about a topic, and discuss it directly with the author. This year’s symposium has a fantastic line-up of presentations. Be sure to check them all out during our 1-2pm afternoon session in the Great Hall.
Zachary Warren – Integrated Kinetic Energy/Direct Energy Weapons.
|The U.S. Army is interested in implementing a combination of kinetic energy and direct energy (KE/DE) weapons to counter rocket, artillery, and mortar (RAM) threats. Lockheed Martin was tasked to simulate a worst-case scenario for a forward operating base (FOB). The U.S. Army specified a variety of different RAM threats to be fired at the FOB in a very short amount of time. Lockheed Martin set out to optimize the amount of KE/DE weapons to mitigate each threat and minimize damage to the FOB. The integrated KE/DE project utilized the Army’s Extended Air Defense (EADSIM) and the Air Force’s Architecture Framework for Simulation, Integration, and Modeling (AFSIM) simulation tools. Research was conducted on direct energy engagements and this information was implemented to convert an EADSIM scenario to an AFSIM scenario. The two simulation suites were compared to determine advantages and limitations. This presentation/poster will describe direct energy weapon technology, development of the simulations, and results of testing.
Anthony Cabri & Thomas Osheka – Impact of Humid, Salt-Water Environment on Steel’s Tensile Test Behavior
|Impact of Humid, Salt-Water Environment on Steel’s Tensile Test Behavior Ultra-High Strength Steels (UHSS) are the predominantly used materials on U.S. Air Force aircraft landing gear systems. The industry standard, AISI 4340, is extremely susceptible to corrosion from the surrounding environment. The Air force has been forced to make great expenditures on aircraft maintenance and corrosion prevention through hazardous procedures such as cadmium plating and painting. In this project, the corrosion resistance of a prototypic UHSS steel, S53, was analyzed – particularly for its resistance to hydrogen embrittlement, also known as hydrogen assisted cracking (HAC). Specifically, this material was studied in a long-term strained condition in a humid, marine environment. This environment is common for aircraft used near the coast or on aircraft carrier flight decks in hot climates. This environment was replicated by performing Slow Strain Rate Tests (SSRT) on specimens of S53, made from tested A-10 landing gear. During the test, simulated seawater solution was kept at temperatures of 21°C, 40°C, and 60°C just below the specimen and contained in an isolated container so that the specimen would have indirect contact with the seawater through humidity and condensation. As well as varying temperature, the strain rate on the samples varied from 10-5, 10-6, and 10-7 (mm/mm)/s. Open Circuit Potential (OCP) was used alongside the SSRT in order to measure the corrosive effects of the seawater. Scanning Electron Microscope (SEM) analysis and hydrogen composition results revealed that hydrogen assisted cracking was the primary cause of specimen failure. Data analysis also revealed that the specimens’ time under load until failure decreased with increased temperatures of the surrounding saltwater environment. Another test composed of a Devanthan cell setup measured the permeation of hydrogen across S53 at varying temperatures. S53 is more susceptible to HAC at elevated temperatures because hydrogen permeation occurs at greater rates with greater temperatures. The longer the material is exposed to a humid, marine environment and the slower the strain rate, the more brittle the material becomes without added strength. However, the results of both SSRT and permeation tests showed that S53 is much more resistant to all corrosive effects than the industry standard, AISI 4340, while providing similar strength properties. S53 is a very promising replacement for AISI 4340 as it may not require cadmium plating or paints in order to be used as effective landing gear for aircraft. More research needs to be done on the effects of real-world environments on its performance before being relied on for this role.
John Ferguson – Experimental Nonlinear Dynamics of a Post-Buckled Composite Laminate Plate
|Composite laminate materials are prevalent in the aerospace industry as programmable high-strength structural options. An increased focus on high-speed and space flight demands an understanding of composite materials subject to extreme combined thermal, aeroelastic and acoustic loading. Under such conditions constrained composite panels may buckle, thus exhibiting nonlinear behavior. This study focuses on a unidirectional carbon fiber epoxy composite laminate plate, a surrogate for more complex composite structures, with four stable static equilibria under fixed-fixed, free-free boundary conditions. The experiment includes pre- and post-buckled modal analysis as well as characterization of the nonlinear response due to transverse excitation. An electrodynamic shaker excites the plate at varying frequencies and loading amplitudes. The dynamic response of the post-buckled plate is measured with the 3D dynamic digital image correlation (DIC) technique combined with a laser vibrometer. The results show single-well and coexisting responses for the four stable equilibria along with chaotic snap through between equilibria. The experimental results of the pre-buckled plate modal analysis are compared to an analytical solution based on classical laminate plate theory (CLPT) and the equation of motion for transverse vibration of laminated plates. Future efforts include modeling and analyzing carbon fiber laminates with respect to damage initiation and material degradation due to high-stress snap through response.
Nick Campbell – Commercial Aerobreaking
| With the revelations that water ice can be found on nearby bodies like asteroids and our moon, commercial space advocates and industry heavyweights are now looking to new value pools in the space economy which could drive cislunar infrastructure development. Colorado’s own, United Launch Alliance, has recently announced that they would become the first customer of in-space propellants derived from space-sourced water. Doing so while providing much needed transportation infrastructure with a planned family of reusable upper stages which will be able to accumulate on orbit and act as freighters, ferrying mass between Earth and Lunar orbits. This possible increase in space activity provides far more opportunities to exploit our planet’s atmosphere for saving rocket propellant and thus increasing the viability of in-space resources. ULA recently teamed up with the University of Colorado to investigate this prospect using their planned, ACES upper stage. In this talk, results from the ACES aerobraking study will be presented and final takeaways will be discussed. It is shown that modest additions of thermal protection materials with the possibility of thermal modulation from hydrogen (which is otherwise vented as a loss) can provide feasible trajectories for the ACES in which significant delivered mass increases (around 200%) can be realized. On going work with newer spacecraft designs will also be included.
Dawson Beatty – Autonomous Ground Navigation (Project DRAGON)
|The field of autonomous ground navigation is prevalent in a variety of environments, from Martian deserts to battlefield urban canyons; as such, the availability of GPS is never guaranteed. For a rover in a GPS-denied environment, relative position determination is limited to small scale, high error, inertial/odometry dead-reckoning measurements; all of these methods rely on integration of previous position estimations, which results in unbounded increase in error over time. In contrast to relative navigation, absolute position estimates– such as measuring distance to landmarks or beacons– do not experience unbounded error growth, although these methods often require highly complicated visual-inertial systems. Project DRAGON (Deployed RF Antennas for GPS-denied Optimization and Environmental Navigation) seeks to demonstrate the ability to correct the error in proprioceptive measurements using a deployed network of RF-enabled pods. As a demonstration, a Clearpath Jackal rover will be tasked with traversing a route through a set of waypoints while avoiding obstacles. The rover will plan its route given its initial position and the terrain of the region, and will select beacon deployment locations to minimize error in trilaterated state estimation along the route. The rover shall host a deployment system to remotely deploy the pods up to distances of 20 meters to lay the groundwork for a localization network.
Emily Ranquest – Airborn sUAS gust observation techniques
|The use of small unmanned aircraft systems (sUAS) has grown exponentially over the past decade for a variety of atmospheric studies. Standard methods of airborne wind measurement, such as multi-hole probes, can be expensive in terms of size, weight, power, and financial cost for implementation on sUAS. A method of wind gust estimation using distributed acceleration sensing in the form of a “gust observer” is proposed that removes the difficulties imposed by other wind measurement and estimation techniques. To test the observer, an aircraft simulation was conducted using MATLAB and Simulink in which the aircraft was buffeted by translational and angular wind velocities. The gust velocity estimates showed convergence to the simulated gusts and less error than Kalman Filter estimates made without acceleration input. Future work includes experimental flight testing in varying gust conditions, analysis of the aircraft states most affected by gusts, and the development of a low altitude turbulence model.
Christopher A. Roseman and Brian Argrow – Targeted Weather Forecasts for small Unmanned Aircraft Systems
|With the rapid development of small Unmanned Aircraft System (sUAS) technology, the FAA predicts that there will be as many as 7 million sUAS flying over the United States by 2020. Safe sUAS operations depend on many factors including reliable communication, collision avoidance, and accurate weather predictions. Weather predictions for sUAS present a particular challenge because the important spatial and temporal forecasting scales are much finer than those of current weather forecasts. Most sUAS operations have less than a 1 hour duration and span a distance of ~ 1 km. The highest resolution forecast that is currently available over the United States is the High Resolution Rapid Refresh (HRRR) weather model. This is a 3 km resolution hourly forecast run by NOAA. Weather hazards not captured by the HRRR can be significant and potentially dangerous to sUAS operations. The present work couples high resolution forecasting with lower order aircraft models in order to develop a tool for sUAS operators to make weather-aware decisions about flight plans. Weather forecasts are calculated using the Weather Research and Forecasting Model (WRF) produced by NCAR and NOAA. The simulations are initialized with the HRRR data. The targeted forecasts performed to date have a spatial resolution of 1 km and a temporal resolution of 15 minutes. The spatial and temporal scale for these simulations allow the forecasts to be run with a reasonable amount of computing power that would be available to many sUAS users. The higher resolution forecasts can provide significantly more detail than the currently available HRRR data. Simple aircraft limitations such as maximum wind speed, gusts, temperature, or humidity allow for aircraft specific advisories to be given based on the flight plan and the weather forecast. The forecasts in this study were made using software that is freely available and require limited computational power. This work has demonstrated the possibility of performing targeted high resolution forecasts for a wide range of sUAS operations.
Joseph Pointer – In-Situ Measurements of Stratospheric Turbulence
|Renewed focus on sustained hypersonic flight in the middle stratosphere has prompted the need for further investigation and detailed modeling of this atmospheric region. Specifically, information on turbulence intensities and suspended particle concentrations is desired at these altitudes, both of which have the potential to disrupt the flight vehicle boundary layer and negatively impact vehicle performance. In 2016, the Hypersonic Flight In the Turbulent Stratosphere (HYFLITS) research team was formed through the Air Force Office of Scientific Research (AFOSR) to address this need. One of the team’s primary objectives is to perform direct measurements and modeling of turbulence intensities and particle concentrations in the altitude range between 20 and 40 km. These measurements will be taken across a variety of geographic locations and conditions to study the influence of Earth topology and convective storms throughout the year on the parameters of interest. With regard to in-situ turbulence measurements, the team has developed a custom fine-wire anemometer system for deployment as a high-altitude balloon payload. The need for sensor calibration to stratospheric pressure and temperature conditions has also led to the design of a custom High-altitude Calibration Wind Tunnel (HiCaT) at the University of Colorado Boulder. The HiCaT produces low velocity flow, between 2 m/s and 10 m/s, at pressure and temperature conditions corresponding to the 20 to 40 km altitude range. In addition to calibration of custom anemometers, HiCaT will be used to obtain new empirical relations of forced convection over fine wires, at low Reynolds numbers, for use in the broader field of anemometry.
Chris Gehrig, Mechanical Engineer, SEAKR Engineering, Inc. Iridium NEXT Processor: How manufacturing and heat pipes became mission critical for providing voice and data capabilities to the world via the largest satellite constellation to date.
|The reconfigurable processing capabilities of the Iridium NEXT mission’s processors present a demanding challenge for thermal management. Traditional conduction cooling techniques do not provide the necessary cooling capacity required for the processors in the critical communications role of the Iridium NEXT constellation. Without properly managing the device temperature, it would be prohibitive to create a system flexible enough for future on-orbit operational advancements during its lifetime. Addressing the problem, SEAKR® integrated and qualified copper water heat pipes – a traditional passive, two phase heat transfer device commonly used for terrestrial electronics systems.
Integrating this technology onto space-bound electronics successfully required significant development of engineering, manufacturing, quality, and test processes. Considerations abound not only for the manufacturing of a flight grade heat pipe but also for the simple attachment of a heat pipe to a device. Further, programs traditionally require production of 1-4 flight units at the culmination of an 18-24 month development cycle. The Iridium NEXT program’s demand for 81 flight units at the end of 24 months drove a rate of 3-4 units per month! Meeting the rigorous production demands, SEAKR® utilized a high volume technique, employing integrated work cells manned by personnel from multiple disciplines – manufacturing, quality assurance and test. This successfully reduced cycle times while still maintaining high quality flight hardware.
These efforts verified the viability of heat pipes within the environments the Iridium NEXT mission processors would be subjected to. The heat pipes continue to effectively manage the processors during the operation of the 65 satellites that have been deployed to date for the Iridium NEXT constellation. Attaining the ability to thermally manage the processing of the Iridium NEXT mission processors laid the foundation for further innovation of SEAKR’s® communication processor capabilities.
Carlos Pinedo – The Design of an International Lunar Village along the Gerlache Crater
Author(s): Carlos Pinedo, Kadambari Suri, Markus Peukert, Mario Maggio, Brendan Perry, Sarah Yenchik, Alexander Verbuch, Zachary
Richardson, Matthew Bair, and Uriel Cain
|This paper looks at determining the infrastructure and technology required to establish a permanent, international lunar village along the rim of one of the craters located at the lunar south pole, specifically de Gerlache Crater. This paper proposes establishing an outpost with provisions for an average occupancy of 10 individuals. Survey missions are scheduled to begin at the start of 2024, with the International lunar Village (ILV) becoming fully operational by the beginning of 2027. The initial setup mission consists of 33 total launches that will be required to survey and set up the ILV. Following missions will involve crews of 4 individuals completing overlapping 6-month rotations for an indefinite length of time, with the ultimate plan to establish a permanent human presence on the moon. Proposed trajectories and launch profiles were determined for optimal propellant expenditure for both manned and unmanned launches. Included in the document are proposed designs for exploration, utility, and crew transport rovers. An inflatable habitat to reside at the edge of the crater was designed with proposed life support and thermal control systems. An additional greenhouse was investigated as a means for self-sustainment and to reduce the amount of resupply required. The mission costs are further significantly decreased due to in-situ resource utilization of water extracted from ice and regolith excavated from within the crater’s permanently dark cold regions. Byproduct regolith would be used as part of the building material for the ILV as well. Lastly, the overall power expenditure to support the ILV is explored
Sean Cohen, Kevin Weed, and Jeremy Lambert of Ball Aerospace – Non-Dimensional Correlations for the Optimization of Micro Pin Fin Arrays
|As electrical systems become smaller and more powerful, they often output higher heat loads over smaller areas. One of the most common approaches to cooling these ever-shrinking electrical components is a micro pin fin array. Given its wide spread use in engineering, many researchers seek to effectively model these geometries so that performance can be predicted and optimized. Thus far, current literature on pin fin arrays has focused primarily on common scale 2D flow. This paper seeks to expand this work to micro 3D geometries, providing a set of non-dimensional correlations for 3D single phase flow over circular and diamond-shaped pin fins. In addition, for engineers without access to finite element software – or for those with access that desire a faster, rougher thermal solution – this paper provides a quasi-two-dimensional approximation for the temperature distribution throughout the fluid and pin fin array.