Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Stack Design”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 829 records · Page 46

Cross slip of extended dislocations in face-centered cubic metals through phase-field modeling

Cross slip is a dislocation mechanism that significantly impacts the mechanical behavior of engineering alloys. Here, in this work, we advance a 3D phase-field dislocation dynamics (PFDD) mesoscale technique to simulate cross slip across a broad range of face-centered cubic (FCC) metals. The formulation incorporates elastic anisotropy, an FCC numerical grid, and a high-fidelity representation of the entire γ -surface from density functional theory for eight FCC metals and no adjustable parameters or rules. The relaxed core structures under zero stress for all metals are predicted to extend in plane. The analytical model for stacking fault width agrees well with the PFDD result under the assumption of elastic isotropy but overestimates it under elastic anisotropy, when the degree of anisotropy is large. The dynamic simulations are designed to elucidate the material parameters that influence the propensity for cross slip. Whether cross slip occurs under a non-Schmid stress or to bypass a hard obstacle, the critical stress to cross slip scales strongly with the anisotropic energy coefficient for a screw dislocation.

36 MATERIALS SCIENCE↗

Test and analysis of Celion 3000/PMR-15, graphite/polyimide bonded composite joints: Data report

Standard single lap, double lap and symmetric step lap bonded joints of Celion 3000/PMR-15 graphite/polyimide composite were evaluated. Composite to composite and composite to titanium joints were tested at 116 K (-250 F), 294 K (70 F) and 561 K (550 F). Joint parameters evaluated are lap length, adherend thickness, adherend axial stiffness, lamina stacking sequence and adherend tapering. Advanced joint concepts were examined to establish the change in performance of preformed adherends, scalloped adherends and hybrid systems. The material properties of the high temperature adhesive, designated A7F, used for bonding were established. The bonded joint tests resulted in interlaminar shear or peel failures of the composite and there were very few adhesive failures. Average test results agree with expected performance trends for the various test parameters. Results of finite element analyses and of test/analysis correlations are also presented.

Cushman, J. B.↗

Oscillating flow loss test results in Stirling engine heat exchangers

The results are presented for a test program designed to generate a database of oscillating flow loss information that is applicable to Stirling engine heat exchangers. The tests were performed on heater/cooler tubes of various lengths and entrance/exit configurations, on stacked and sintered screen regenerators of various wire diameters and on Brunswick and Metex random fiber regenerators. The test results were performed over a range of oscillating flow parameters consistent with Stirling engine heat exchanger experience. The tests were performed on the Sunpower oscillating flow loss rig which is based on a variable stroke and variable frequency linear drive motor. In general, the results are presented by comparing the measured oscillating flow losses to the calculated flow losses. The calculated losses are based on the cycle integration of steady flow friction factors and entrance/exit loss coefficients.

Koester, G.↗

Weaves as an Interconnection Fabric for ASIM's and Nanosatellites

Many of the micromachines under consideration require computer support, indeed, one of the appeals of this technology is the ability to intermix mechanical, optical, analog, and digital devices on the same substrate. The amount of computer power is rarely an issue, the sticking point is the complexity of the software required to make effective use of these devices. Micromachines are the nano-technologist's equivalent of 'golden screws'. In other words, they will be piece parts in larger assemblages. For example, a nano-satellite may be composed of stacked silicon wafers where each wafer contains hundreds to thousands of micromachines, digital controllers, general purpose computers, memories, and high-speed bus interconnects. Comparatively few of these devices will be custom designed, most will be stock parts selected from libraries and catalogs. The novelty will lie in the interconnections. For example, a digital accelerometer may be a component part in an adaptive suspension, a monitoring element embedded in the wrapper of a package, or a portion of the smart skin of a launch vehicle. In each case, this device must inter-operate with other devices and probes for the purposes of command, control, and communication. We propose a software technology called 'weaves' that will permit large collections of micromachines and their attendant computers to freely intercommunicate while preserving modularity, transparency, and flexibility. Weaves are composed of networks of communicating software components. The network, and the components comprising it, may be changed even while the software, and the devices it controls, are executing. This unusual degree of software plasticity permits micromachines to dynamically adapt the software to changing conditions and allows system engineers to rapidly and inexpensively develop special purpose software by assembling stock software components in custom configurations.

Gorlick, Michael M.↗

Proton Exchange Membrane (PEM) fuel Cell for Space Shuttle

Development of a PEM fuel cell powerplant (PFCP) for use in the Space Shuttle offers multiple benefits to NASA. A PFCP with a longer design life than is delivered currently from the alkaline fuel will reduce Space Shuttle Program maintenance costs. A PFCP compatible with zero-gravity can be adapted for future NASA transportation and exploration programs. Also, the commercial PEM fuel cell industry ensures a competitive environment for select powerplant components. Conceptual designs of the Space Shuttle PFCP have resulted in identification of key technical areas requiring resolution prior to development of a flight system. Those technical areas include characterization of PEM fuel cell stack durability under operational conditions and water management both within and external to the stack. Resolution of the above issues is necessary to adequately control development, production, and maintenance costs for a PFCP.

Hoffman, William C., III↗

Design, Prototyping, and Testing of a Novel Flowpath with an Array of Six 3D Matrix Vitvo Bioreactors for the NASA Bioculture System

The NASA Bioculture System is an advanced cell culture closed-loop system containing highly automated flowpaths designed to conduct long term biology experiments on ISS with earth remote controllable medium flow, temperature, gas composition, medium exchange, cell sampling and fixation. This technology was already demonstrated with successful cardiomyocyte and osteocyte cultures experiments onboard the ISS and is now supporting NASA PI science. The Bioculture System, however, can only support 10 cassettes with disposable flowpaths, each containing a single hollow fiber bioreactor with a culture capacity of about 2ml. This constraint not only severely limits the number of investigators that can conduct experiments in space, but also subjects the experiments to limitations in the number of replicates and conditions that can be studied. To address these limitations, we sought a novel design solution to maximize the number of separate bioreactor cultures and volume that can be conducted simultaneously. To this end we designed, prototyped, and are now testing a six-Vitvo 3D Matrix 2ml bioreactor insert that replaces the conventional Bioculture System hollow fiber bioreactor. This design will allow the Bioculture System to support up to 60 different bioreactors and samples at once. Specifically, the novel gas-tight containment housing insert contains six COTS Rigenerand VITVO bioreactors stacked on each side of a heat sink powered by the existing heating element and pair of temperature sensors. Medium will be distributed into each bioreactor's cell-free chamber via its built-in Luer connector, then across the 3D matrix to the cell chamber, dissipating laminar flow and limiting fluid shear stresses that might mechanostimulate cell cultures. Gas (5% CO2 in air) will be supplied directly to the bioreactor gas-tight housing for exchange via the bioreactor flat-surface gas-permeable membranes, eliminating the need for the existing Bioculture System cassette oxygenator. If successfully implemented on ISS, this new multi-bioreactor insert for the Bioculture System has the potential to make real-time cell science experimentation in space more efficient and accessible to more investigators.

Ma, Kristin R.↗

Automated Ply-By-Ply Lamination and in-Situ Consolidation of Dry Carbon Fiber Non-Crimp Fabrics for High-Rate Aircraft Manufacturing of Structural Aircraft Components

NASA’s Hi-Rate Composites Aircraft Manufacturing (HiCAM) program addresses market needs to advance structural aircraft composite manufacturing technologies to significantly increase production rates. Dry, non-crimp fabric (NCF) carbon materials infused with advanced resin systems offer a promising solution to these manufacturing demands. Northrop Grumman’s Automated Stiffener Forming (ASF) technology has been adapted for ply-by-ply, in-situ processing of NCF materials. The modular ASF process accommodates flexibility in the laminate stacking, while allowing for ply drops, ply additions, and yaw, pitch, and roll in the laminate geometry. To adapt the ASF process for NCF materials, heating technologies and roller compaction processes were designed and tested on representative structural aircraft part geometries. Key success criteria for the ASF process with NCF materials is forming quality and preform compaction. Trials were performed with multiple NCF materials: unidirectional up to quad-axial formats. The NCF constituents, veils, stitching, and binders, were evaluated with the ASF process. The material performance in the ASF process and the resulting preform quality are presented.

dry carbon fiber materials↗

Automated Ply-By-Ply Lamination and in-Situ Consolidation of Dry Carbon Fiber Non-Crimp Fabrics for High-Rate Aircraft Manufacturing of Structural Aircraft Components

NASA’s Hi-Rate Composites Aircraft Manufacturing (HiCAM) program addresses market needs to advance structural aircraft composite manufacturing technologies to significantly increase production rates. Dry, non-crimp fabric (NCF) carbon materials infused with advanced resin systems offer a promising solution to these manufacturing demands. Northrop Grumman’s Automated Stiffener Forming (ASF) technology has been adapted for ply-by-ply, in-situ processing of NCF materials. The modular ASF process accommodates flexibility in the laminate stacking, while allowing for ply drops, ply additions, and yaw, pitch, and roll in the laminate geometry. To adapt the ASF process for NCF materials, heating technologies and roller compaction processes were designed and tested on representative structural aircraft part geometries. Key success criteria for the ASF process with NCF materials is forming quality and preform compaction. Trials were performed with multiple NCF materials: unidirectional up to quad-axial formats. The NCF constituents, veils, stitching, and binders, were evaluated with the ASF process. The material performance in the ASF process and the resulting preform quality are presented.

dry carbon fiber materials↗

Numerical Simulations of A Conceptual MSR-EES Shoulder Recession

The present study demonstrates our in-house material response solver, Icarus's capability to simulate the ablative conditions, including pyrolysis effects due to the interaction between hypersonic boundary layers and the thermal protection system (TPS). A conceptual aeroshell shoulder design, which undergoes mission-relevant flow and material conditions, is selected for the demonstration purpose. LAURA, a structured flow solver, is used to solve flow around the shoulder at several trajectory points of a flight path. The aerothermal dataset obtained from LAURA is used to enforce boundary conditions on the aeroshell wall to simulate ablation processes. The two-layered material system is stacked with HEEET (TPS) and Aluminum (actual material). A set of base parameters, such as the angle of material orientation with respect to the flow direction, convective heat-transfer co-efficient, and aerothermal boundary conditions on the rear end of the HEEET material layer, is selected to conduct a base-case simulation. A small amount of recession was observed, indicating that the design should be fine to go through the selected flow and material conditions. Furthermore, the parameters mentioned above are individually altered and are observed to affect the shoulder design's recession compared to the base case. Verification of our Icarus setup was also carried out using a one-dimensional grid and FIAT, a one-dimensional material-response solver, to build credibility for our results. As the current work is an uncoupled fluid-material-response simulation, a local sharp mesh deformation in the recessed surface near the shoulder corner is observed.

Prakash Shrestha↗

Overview of the Space Launch System Ascent Aeroacoustic Environment Test Program

Characterization of accurate flight vehicle unsteady aerodynamics is critical for component and secondary structure vibroacoustic design. The Aerosciences Branch at the National Aeronautics and Space Administration (NASA) Marshall Space Flight Center has conducted a test at the NASA Ames Research Center (ARC) Unitary Plan Wind Tunnels (UPWT) to determine such ascent aeroacoustic environments for the Space Launch System (SLS). Surface static pressure measurements were also collected to aid in determination of local environments for venting, CFD substantiation, and calibration of the flush air data system located on the launch abort system. Additionally, this test supported a NASA Engineering and Safety Center study of alternate booster nose caps. Testing occurred during two test campaigns: August - September 2013 and December 2013 - January 2014. Four primary model configurations were tested for ascent aeroacoustic environment definition. The SLS Block 1 vehicle was represented by a 2.5% full stack model and a 4% truncated model. Preliminary Block 1B payload and manned configurations were also tested, using 2.5% full stack and 4% truncated models respectively. This test utilized the 11 x 11 foot transonic and 9 x 7 foot supersonic tunnel sections at the ARC UPWT to collect data from Mach 0.7 through 2.5 at various total angles of attack. SLS Block 1 design environments were developed primarily using these data. SLS Block 1B preliminary environments have also been prepared using these data. This paper discusses the test and analysis methodology utilized, with a focus on the unsteady data collection and processing.

Herron, Andrew J.↗

Energy Storage Financing: Operations & Market Strategy

This study investigates the impact that operations and market strategy have on the design and value of an energy storage system on three levels of the facility: the cell level, the system level, and the project level. The study provides insights for developers, capital providers, customers and policy makers into the impact different operational strategies have on effectiveness of energy storage system in today's emerging market. Energy storage systems can be used for a variety of usage profiles, with the choice having a profound impact on their performance, lifespan, and revenue potential. Most evaluations of application stacking only look at the possible revenue potential without understanding the increased costs and potential for major damage to the cells. Evaluating the impact of operational choices is critical to understanding the risk adjusted return from energy storage project investment. This is the fifth study in the Energy Storage Financing Study series, which is designed to investigate challenges surrounding the financing of energy storage projects in the U.S., promoting greater technology and project risk transparency, reducing project transaction costs, and supporting a level playing field for innovative energy storage technologies.

25 ENERGY STORAGE↗

Deformation mechanisms in single crystal Ni-based concentrated solid solution alloys by nanoindentation

Nanoindentation is a critical technique to probe mechanical properties at the micrometer and sub-micrometer scales, accompanied by challenges from indentation size effect, pile-up/sink-in effect, and strain rate sensitivity. In this work, different nanoindentation techniques have been employed to explore Ni-based concentrated solid solution alloys (CSAs) with the addition of 3d transition metal elements including Co, Cr, Mn, and Fe, including unique single-crystal Ni, NiCo, NiFe, Ni 80 Cr 20 , and NiCoFeCr samples with (100) surfaces. A procedure of nanoindentation tests and data analysis/correction have been developed, and a data set of hardness, elastic modulus, strain rate sensitivity, and activation volume for Ni-based CSAs are provided, including the less explored binary alloys such as Ni 80 Cr 20 and Ni 80 Mn 20 . The results show that the type of alloying elements is more critical than the number of elements in strengthening: Co does not provide strengthening in NiCo, while Cr, Mn, and Fe are effective strengthening elements. Cr is the most effective among all the 3d transition metal elements. Furthermore, atomic-level lattice distortion is responsible for the strengthening and the role of stacking fault energy is insignificant in Ni-based CSAs at room temperature. In summary, nanoindentation shows increasing promise as a reliable and fast tool to provide comprehensive mechanical information for new alloy design and development.

36 MATERIALS SCIENCE↗

Fuel Cell Stack Model for Real-Time Simulation of Grid-Connected Applications

Fuel cell stacks coupled with electrolyzers and hydrogen storage sites can be a promising category of distributed energy resources for both grid-connected and stand-alone power systems. However, because of high costs, at-scale hardware testing of fuel cell stacks for grid-connected applications is not economically viable at present. A model-based system that can accurately captures the steady-state and dynamic response of fuel cell stacks over long time periods (hours), is needed. This paper demonstrate a real-time electromagnetic transient model of a megawatt-scale, grid-connected proton exchange membrane fuel cell stack, coupled with a mass-based hydrogen storage system. This model can emulate the electrical steady-state and dynamic response of grid-connected fuel cell stacks. We validate the model using the response of commercial hardware fuel cell stacks and analytical models in the literature - using a digital real-time simulator (RSCAD). The proposed real-time model is then used to simulate cases spanning different time horizons and to design controller-hardware-in-the-loop experiments to evaluate controllers for hydrogen stations.

activation potential↗

Erectable/deployable concepts for large space system technology

Erectable/deployable space structure concepts particularly relating to the development of a science and applications space platform are presented. Design and operating features for an automatic coupler clevis joint, a side latching detent joint, and a module-to-module auto lock coupler are given. An analysis of the packaging characteristics of stacked subassembly, single fold, hybrid, and double fold concepts is given for various platform structure configurations. Payload carrier systems and assembly techniques are also discussed.

Agan, W. E.↗

The Ares I-1 Flight Test--Paving the Road for the Ares I Crew Launch Vehicle

In accordance with the U.S. Vision for Space Exploration and the nation's desire to again send humans to explore beyond Earth orbit, NASA has been tasked to send human beings to the moon, Mars, and beyond. It has been 30 years since the United States last designed and built a human-rated launch vehicle. NASA is now building the Ares I crew launch vehicle, which will loft the Orion crew exploration vehicle into orbit, and the Ares V cargo launch vehicle, which will launch the Lunar Surface Access Module and Earth departure stage to rendezvous Orion for missions to the moon. NASA has marshaled unique resources from the government and private sectors to perform the technically and programmatically complex work of delivering astronauts to orbit early next decade, followed by heavy cargo late next decade. Our experiences with Saturn and the Shuttle have taught us the value of adhering to sound systems engineering, such as the "test as you fly" principle, while applying aerospace best practices and lessons learned. If we are to fly humans safely aboard a launch vehicle, we must employ a variety of methodologies to reduce the technical, schedule, and cost risks inherent in the complex business of space transportation. During the Saturn development effort, NASA conducted multiple demonstration and verification flight tests to prove technology in its operating environment before relying upon it for human spaceflight. Less testing on the integrated Shuttle system did not reduce cost or schedule. NASA plans a progressive series of demonstration (ascent), verification (orbital), and mission flight tests to supplement ground research and high-altitude subsystem testing with real-world data, factoring the results of each test into the next one. In this way, sophisticated analytical models and tools, many of which were not available during Saturn and Shuttle, will be calibrated and we will gain confidence in their predictions, as we gain hands-on experience in operating the first of two new launch vehicle systems. The Ares I-1 flight test vehicle (FTV) will incorporate a mix of flight and mockup hardware, reflecting a configuration similar in mass, weight, and shape (outer mold line or OML) to the operational vehicle. It will be powered by a four-segment reusable solid rocket booster (RSRB), which is currently in Shuttle inventory, and will be modified to include a fifth, inert segment that makes it approximately the same size and weight as the five segment RSRB, which will be available for the second flight test in 2012. The Ares I-1 vehicle configuration is shown. Each test flight has specific objectives appropriate to the design analysis cycle in progress. The Ares I-1 demonstration test, slated for April 2009, gives NASA its first opportunity to gather critical data about the flight dynamics of the integrated launch vehicle stack, understand how to control its roll during flight, and other characterize the severe stage separation environment that the upper stage will experience during future operational flights. NASA also will begin the process of modifying the launch infrastructure and fine-tuning ground and mission operational scenarios, as NASA transitions from the Shuttle to the Ares/Orion system.

Davis, Stephan R.↗

Deep Drilling and Sampling via the Wireline Auto-Gopher Driven by Piezoelectric Percussive Actuator and EM Rotary Motor

The ability to penetrate subsurfaces and perform sample acquisition at depths of meters is critical for future NASA in-situ exploration missions to bodies in the solar system, including Mars and Europa. A corer/sampler was developed with the goal of acquiring pristine samples by reaching depths on Mars beyond the oxidized and sterilized zone. To developed rotary-hammering coring drill, called Auto-Gopher, employs a piezoelectric actuated percussive mechanism for breaking formations and an electric motor rotates the bit to remove the powdered cuttings. This sampler is a wireline mechanism that is incorporated with an inchworm mechanism allowing thru cyclic coring and core removal to reach great depths. The penetration rate is being optimized by simultaneously activating the percussive and rotary motions of the Auto-Gopher. The percussive mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) mechanism that is driven by piezoelectric stack and that was demonstrated to require low axial preload. The Auto-Gopher has been produced taking into account the a lessons learned from the development of the Ultrasonic/Sonic Gopher that was designed as a percussive ice drill and was demonstrated in Antarctica in 2005 to reach about 2 meters deep. A field demonstration of the Auto-Gopher is currently being planned with objective of reaching as deep as 3 to 5 meters in tufa subsurface.

Auto-Gopher↗

Status of the Advanced Oxygen Generation Assembly Design

Future Exploration missions will require an Oxygen Generation Assembly (OGA) to electrolyze water to supply oxygen for crew metabolic consumption. The system design will be based on the International Space Station (ISS) OGA but with added improvements based on lessons learned during ISS operations and technological advances since the original OGA was designed and built. The goal of these improvements will be to reduce system weight, crew maintenance time and spares mass while increasing reliability. Over the past year, the team has performed additional design reviews, testing and analysis in an effort to optimize upgrade efforts and achieve the best value that meets Exploration mission requirements. Upgrades that will be incorporated include: redesign of the electrolysis cell stack, redesign of the hydrogen dome, replacement of the hydrogen sensors, redesign of the recirculation loop deionizing bed, and incorporation of recirculation loop nitrogen purging and water flushing. The ISS OGA will be upgraded to an Advanced OGA (AOGA) configuration and its operation demonstrated in a relevant flight environment.

Oxygen Generation Assembly↗

Status of the Advanced Oxygen Generation Assembly Design

Future Exploration missions will require an Oxygen Generation Assembly (OGA) to electrolyze water to supply oxygen for crew metabolic consumption. The system design will be based on the International Space Station (ISS) OGA but with added improvements based on lessons learned during ISS operations and technological advances since the original OGA was designed and built. The goal of these improvements will be to reduce system weight, crew maintenance time and spares mass while increasing reliability. Over the past year, the team has performed additional design reviews, testing and analysis in an effort to optimize upgrade efforts and achieve the best value that meets Exploration mission requirements. Upgrades that will be incorporated include: redesign of the electrolysis cell stack, redesign of the hydrogen dome, replacement of the hydrogen sensors, redesign of the recirculation loop deionizing bed, and incorporation of recirculation loop nitrogen purging and water flushing. The ISS OGA will be upgraded to an Advanced OGA (AOGA) configuration and its operation demonstrated in a relevant flight environment.

Oxygen Generation Assembly↗