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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.

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At least 1,279 records · Page 71
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Multidisciplinary Dynamic Testing Challenges in Validating the NASA Artemis Architecture

NASA is in the midst of bold and exciting next steps in human exploration and spaceflight. The designs of the new Space Launch System (SLS), the Orion spacecraft and the Exploration Ground Systems (EGS) for vehicle processing and launch are essentially complete and there has been significant progress in manufacturing and assembly of specific hardware for the Artemis I and Artemis II missions. Equally as important, the program level and integrated system level testing and analyses are also well underway to support integrated verification, validation, and certificate of flight readiness (CoFR) for the first Artemis mission. Testing and analysis are key to addressing technical challenges that the Artemis missions offer. Building block approaches are required that provide the right balance between component, system, and/or element level testing that satisfies verification and validation objectives and where, uncertainties are quantified and minimized. Artemis I is a system of systems that requires a fusion of test and analysis that adeptly characterizes critical interfaces between major program elements. NASA is implementing new in-situ testing that fuse traditional aerospace structures with civil structures, such as the Integrated Modal Test for the Artemis I vehicle where the Mobile Launcher and Crawler Transporter serve as a support structure whose dynamics couple with that of the Artemis I vehicle. This new paradigm requires a closer inspection of structural behavior of the Crawler Transporter and the Mobile Launcher as they now serve multiple purposes. This requires a paradigm shift to look beyond experimental modal techniques and incorporates operational modal analysis techniques to validate dynamic models from data collected during rollout to the launch pad. A further complicating factor is the Crawler Transporter generated ground forces have numerous harmonics making extracting dynamic responses of the Artemis I, Mobile Launcher, and Crawler Transporter coupled system challenging. This discussion explores all these challenges with and attempts to understand how we best build confidence in systems and system-of-systems performance capabilities and margins and understand uncertainties.

Joel W Sills↗
NASA NTRS1977

Analysis of shock pulses for environmental tests

Specifications for shock testing of components that will be used on the Space Shuttle vehicles require very high acceleration levels. A special shock machine was built for testing of rocket components to determine if they can meet the specified accelerations. Calibrations of transducers and methods to monitor the shock tests raised several signature-analysis questions. In this report, calibration capabilities of shock accelerometers are found to be limited to 10,000g. Equivalency of the mechanical shock test and the rocket pyrotechnic shock are examined, and two simple relationships for equivalency are proposed. Five different pulse signature-analysis techniques are tested on analytical and experimental pulse data and recommendations are made for the signature technique which most clearly identifies the magnitude of the impulse applied to the test specimen.

Houghton, J. R.↗
NASA NTRS1998

Accelerometer Placement for the International Space Station Node Modal Test

Accelerometer location analysis for the modal survey test of the International Space Station Node is described. Three different approaches were utilized: (1) Guyan reduction; (2) Iterative Guyan reduction; and (3) The average driving point residue (ADPR) method. Both Guyan approaches worked well, but poor results were observed for the ADPR method. Although the iterative Guyan approach appears to provide the best set of sensor locations, it is intensive computationally, becoming impractical for large initial location sets. While this is computer dependent, it appears that initial sets larger than about 1500 degrees of freedom are impractical for the iterative technique.

Tinker, Michael L.↗
NASA NTRS2017

NASA-STD-6001B Test 7: Impact of Test Methodology and Detection Advancements on the Obsolescence of Historical Offgas Data

NASA-STD-6001B states "all nonmetals tested in accordance with NASA-STD-6001 should be retested every 10 years or as required by the responsible program/project." The retesting of materials helps ensure the most accurate data are used in material selection. Manufacturer formulas and processes can change over time, sometimes without an update to product number and material information. Material performance in certain NASA-STD-6001 tests can be particularly vulnerable to these changes, such as material offgas (Test 7). In addition, Test 7 analysis techniques at NASA White Sands Test Facility were dramatically enhanced in the early 1990s, resulting in improved detection capabilities. Low level formaldehyde identification was improved again in 2004. Understanding the limitations in offgas analysis data prior to 1990 puts into question the validity and current applicability of that data. Case studies on Super Koropon (Registered trademark) and Aeroglaze (Registered trademark) topcoat highlight the importance of material retesting.

Buchanan, Vanessa D.↗
NASA NTRS1980

Turbine blade structural dynamic analysis

The paper presents structural dynamic analysis and test results for the Space Shuttle Main Engine turbine blades. Athough these blades are designed to avoid coincidence of natural frequencies with harmonic excitation forces, the complexity of the turbine hardware, its nonlinearities and lack of information regarding the forcing function have led to fatigue failures. A comparison of single-blade analysis and test modal frequencies, shapes, and stresses is given; analysis techniques to describe the forcing function, compute dynamic responses, and incorporate the nonlinearities of Coulomb-friction dampers are presented. Recommendations are made for new research to improve forcing function computations and structural damping estimates used in the analysis.

Dickerson, E. O.↗
NASA NTRS2003

Evaluation of a Singular Value Decomposition Approach for Impact Dynamic Data Correlation

Impact dynamic tests are used in the automobile and aircraft industries to assess survivability of occupants during crash, to assert adequacy of the design, and to gain federal certification. Although there is no substitute for experimental tests, analytical models are often developed and used to study alternate test conditions, to conduct trade-off studies, and to improve designs. To validate results from analytical predictions, test and analysis results must be compared to determine the model adequacy. The mathematical approach evaluated in this paper decomposes observed time responses into dominant deformation shapes and their corresponding contribution to the measured response. To correlate results, orthogonality of test and analysis shapes is used as a criterion. Data from an impact test of a composite fuselage is used and compared to finite element predictions. In this example, the impact response was decomposed into multiple shapes but only two dominant shapes explained over 85% of the measured response

Horta, Lucas G.↗
NASA NTRS1986

COFS 3: Multibody dynamics and control technology

COFS 3 is the third project within the Control of Flexible Structures (COFS) program. It deals with developing multibody dynamics and control technology for large space structures. It differs from COFS 1 and 2 in two respects. First, it addresses a more complex class of structure, and second it is basically a scale model ground test and analysis program while COFS 1 and 2 feature Shuttle flight experiments. The specific technology thrusts within COFS 3 are model sensitivities, test methods, analysis validation, systems identification, and vibration suppression. The COFS 3 project will develop the methods for using dynamically scaled models and analysis to predict the structural dynamics of large space structures. The project uses the space station as a focus because it is typical of the structures of interest and provides the first opportunity to obtain full-scale on-orbit dynamics data.

Letchworth, Robert↗
NASA NTRS1977

Atmospheric model development in support of SEASAT. Volume 1: Summary of findings

Atmospheric analysis and prediction models of varying (grid) resolution were developed. The models were tested using real observational data for the purpose of assessing the impact of grid resolution on short range numerical weather prediction. The discretionary model procedures were examined so that the computational viability of SEASAT data might be enhanced during the conduct of (future) sensitivity tests. The analysis effort covers: (1) examining the procedures for allowing data to influence the analysis; (2) examining the effects of varying the weights in the analysis procedure; (3) testing and implementing procedures for solving the minimization equation in an optimal way; (4) describing the impact of grid resolution on analysis; and (5) devising and implementing numerous practical solutions to analysis problems, generally.

Kesel, P. G.↗
DOE OSTI2021

Review of Design Elements within Power Infrastructure Cyber–Physical Test Beds as Threat Analysis Environments

Cyber–physical systems (CPSs) are an integral part of modern society; thus, enhancing these systems’ reliability and resilience is paramount. Cyber–physical testbeds (CPTs) are a safe way to test and explore the interplay between the cyber and physical domains and to cost-effectively enhance the reliability and resilience of CPSs. Here a review of CPT elements, broken down into physical components (simulators, emulators, and physical hardware), soft components (communication protocols, network timing protocols), and user interfaces (visualization-dashboard design considerations) is presented. Various methods used to validate CPS performance are reviewed and evaluated for potential applications in CPT performance validation. Last, initial simulated results for a CPT design, based on the IEEE 33 bus system, are presented, along with a brief discussion on how model-based testing and fault–injection-based testing (using scaling and ramp-type attacks) may be used to help validate CPT performance.

14 SOLAR ENERGY↗
NASA NTRS1975

Laser geodynamic satellite thermal/optical/vibrational analyses and testing, volume 2, book 1 technical report

The results are presented of a retroreflector performance improvement program. The following areas of the program are discussed: retroreflector dimensional verification, initial optical performance analysis, LAGEOS test retroreflector rework, final optical performance analysis, optical performance tests, evaluations and conclusions, and laser wavelength evaluation and dihedral angle selection. Data tables, diagrams, graphs, and photographs are included.

Source record↗
NASA NTRS1994

Static stability of a three-dimensional space truss

Space station requirements for power have resulted in a need for photovoltaic solar arrays possessing large blanket surface area. However, due to the limited shuttle payload volume solar array designers have been driven to a deployable concept that by nature is extremely flexible. The principal support for this array system is the Folding Articulating Square Truss Mast (FASTMast). In order to accomodate service loads the FASTMast is expected to exhibit nonlinear behavior which could possibly result in structural instability. Presented herein are the results of the Lewis Research Center test and analysis efforts performed in an effort to characterize the FASTMast structural behavior in terms of stability. Results include those obtained from recent nonlinear testing and analysis involving a 1/10 segment of the FASTMast flight article. Implications of these results as they relate to expected behavior of the flight unit will also be discussed.

Shaker, John F.↗
NASA NTRS1994

Static Stability of a Three-Dimensional Space Truss

Space Station requirements for power have resulted in a need for photovoltaic solar arrays possessing large blanket surface area. However, due to the limited Shuttle payload volume solar array designers have been driven to a deployable concept that by nature is extremely flexible. The principal support for this array system is the Folding Articulating Square Truss Mast (FASTMast). In order to accommodate service loads the FASTMast is expected to exhibit nonlinear behavior which could possibly result in structural instability. Presented herein are the results of the Lewis Research Center test and analysis efforts performed in an effort to characterize the FASTMast structural behavior in terms of stability. Results include those obtained from recent nonlinear testing and analysis involving a 1/10 segment of the FASTMast flight article. Implications of these results as they relate to expected behavior of the flight unit will also be discussed.

Shaker, John F.↗
DOE OSTI2020

Manufacturing of magnesium/aluminum bimetallic ring components by friction stir assisted simultaneous forging and solid-state joining

Here, a bimetallic ring component is forged by a friction stir assisted forging (FS-forging). A cylindrical bimetallic blank, magnesium AZ31 cylinder (Mg core) tightly fitted inside an aluminum 6061-T6 tube (Al skin), is used. In the FS-forging, the frictional heat and stirring of rotating tool forge the blank into a desired shape, while simultaneously generate a solid-state joint between the Mg core and the Al skin, without additional external heating, as confirmed by the microstructural analysis and mechanical tests. The microstructural analysis also shows that the characteristics of the solid-state joint can be different depending on the process parameters.

42 ENGINEERING↗
DOE OSTI2022

Conversion kinetics during melting of simulated nuclear waste glass feeds measured by dissolution of silica

In this work, we experimentally investigated the batch-to-glass conversion kinetics of two low-activity and two high-level nuclear waste melter feeds that represent widely different behavior during melting; tests comprised thermogravimetric analysis, the feed expansion test, evolved gas analysis, and x-ray diffraction. Our study indicates that the conversion processes, which include gas-evolving reactions, dissolution of crystalline phases, and primary foam expansion and collapse, are interconnected and influenced by the feed’s thermal history. The fraction of dissolved silica was adopted as a measure of the extent of conversion inside the cold cap—the floating layer of feed material on the top surface of the melt in an electric melter. The interface between the cold cap and the free-flowing melt below was associated with a constant fraction of dissolved silica. The estimated viscosity of glass-forming melt at this interface lies within a narrow range for the feeds studied.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

FIC Vulnerability Profile

The FIC team is engaged with Pacific Northwest National Laboratory’s (PNNL’s) Shamrock Cyber Team to provide cybersecurity analyses of the FIC software. Shamrock offers both Threat-Based Analysis services and Secure Software Development services. These services are ultimately used to understand and mitigate threats against software and to reduce vulnerabilities in software, thus improving overall cybersecurity and informing decision makers. Shamrock’s Secure Software Development services, specifically Static Analysis Security Testing (SAST) and Open-Source Analysis (OSA), produced this Vulnerability Profile.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1974

Space shuttle maneuvering engine reusable thrust chamber program. Task 11: Stability analyses and acoustic model testing data dump

The combustion stability characteristics of engines applicable to the Space Shuttle Orbit Maneuvering System and the adequacy of acoustic cavities as a means of assuring stability in these engines were investigated. The study comprised full-scale stability rating tests, bench-scale acoustic model tests and analysis. Two series of stability rating tests were made. Acoustic model tests were made to determine the resonance characteristics and effects of acoustic cavities. Analytical studies were done to aid design of the cavity configurations to be tested and, also, to aid evaluation of the effectiveness of acoustic cavities from available test results.

Oberg, C. L.↗