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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Dual-Wavelength Simultaneous Patterning of Degradable Thermoset Supports for One-Pot Embedded 3D Printing

Vat photopolymerization (VP) techniques have enabled the fabrication of complex geometries while balancing high precision and fast processing times. 3D printed objects are traditionally built layer-by-layer with newly cured layers being structurally supported by previous ones. Fabricating unsupported features such as overhangs and arches risks misalignment and sagging, limiting the range of accessible designs. To overcome this issue, support structures are fabricated along with the primary object as temporary scaffolds that provide stability and conserve print fidelity. For VP specifically, patterning dissolvable sacrificial supports is attractive to avoid manual removal after printing. In this study, we demonstrate a base-degradable thermoset to pattern print supports in a one-pot formulation along with the primary structural material. Efficient printing is enabled using a dual-wavelength negative imaging (DWNI) DLP printer that patterns the degradable thermoset with visible light and the permanent network with UV light, which are simultaneously projected using a single digital micromirror device (DMD). Printed objects undergo thermal postprocessing to enhance the final conversion of the primary material, after which thermoset supports are degraded in a basic, aqueous solution. This approach provides a robust method for the dual-wavelength patterning of sacrificial thermoset supports, broadening the range of accessible 3D printable materials and geometries.

3D printing↗
NASA NTRS2017

Fractal Stiffening

A structural support having fractal-stiffening and method of fabricating the support is presented where an optimized location of at least three nodes is predetermined prior to fabricating the structural support where a first set of webs is formed on one side of the support and joined to the nodes to form a first pocket region. A second set of webs is formed within the first pocket region forming a second pocket region where the height of the first set of webs extending orthogonally from the side of the support is greater than the second set of webs extending orthogonally from the support.

Harper, David William↗
DOE OSTI2022

Development of a 120-mm Aperture Nb 3 Sn Dipole Coil With Stress Management

This paper describes a 120-mm aperture 2-layer dipole coil with stress management (SM) developed at Fermilab based on cos-theta coil geometry. A model of the coil support structure made of plastic was printed using additive manufacturing technology and used for practice coil winding. The real coil support structure was printed using the 316 stainless steel. The results of the SM structure size control and the key coil fabrication steps are reported in the paper. Finally, the design of coil SM structure and the coil FEA in the dipole mirror test configurations are presented and discussed.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1981

Low thermal conductance rigidizer for reducing torsional oscillations in cryogenic Dewars

A rigidizer, which provides greater rigidity against torsional oscillations, is highly resistant to radial motions, and has low thermal conductivity, has been developed to decrease vibrational levels affecting infrared detectors operated in cryostats (e.g., HD-3L Dewar) in aircraft such as NASA's Kuiper Airborne Observatory. The rigidizer is composed of two triangular elements and an intermediate support structure which joins them at the centers of their sides. The reentrant design provides a long heat path, while the triangular truss structure provides high rigidity in the horizontal plane. The structure is relatively compliant in the vertical direction, a desirable feature since the internal structure of the Dewar contracts as it cools. Rigidity in the vertical direction is provided by the neck tube. The support structure is quite compact. Several variants of the rigidizer have been fabricated, using flat sheets of G-10 fiberglass epoxy in thicknesses between 0.75-1.5 mm for the upper and lower truss assemblies, and either G-10 or stainless steel for the intermediate structure.

Harper, D. A.↗
DOE OSTI2020

Direct writing nozzle system for additive manufacturing

A nozzle apparatus used for extruding a material includes an internal spindle that imparts motion into the extruding material, the internal spindle having a base; a multiple degree-of-freedom pivot at the base of the internal spindle, and a drive mechanism that controls the motion of the internal spindle. In one embodiment the material is a semi-solid metal or alloy. In another embodiment the material is a shear thinning mixture or material. In yet embodiment the material is a thixotropic mixture or material. The nozzle apparatus can be used for making a three-dimensional object with the steps of providing a material; providing a nozzle that extrudes the material, the nozzle having an internal spindle that imparts motion into the material; positioning the nozzle above a support structure; and moving the nozzle in a three-dimensional pattern while extruding the material through the nozzle onto the support structure or onto the material previously deposited.

42 ENGINEERING↗
NASA NTRS1987

Dynamic analysis of the large deployable reflector

The Large Deployable Reflector (LDR) is to be an astronomical observatory orbiting above Earth's obscuring atmosphere and operating in the spectral range between 30 microns and 1000 microns wavelength. The LDR will be used to study such astronomical phenomena as stellar and galactic formation, cosmology, and planetary atmospheres. The LDR will be the first observatory to be erected and assembled in space. This distinction brings with it several major technological challenges such as the development of ultra-lightweight deployable mirrors, advanced mirror fabrication techniques, advanced structures, and control of vibrations due to various sources of excitation. The purpose of this analysis is to provide an assessment of the vibrational response due to secondary mirror chopping and LDR slewing. The dynamic response of two 20-m LDR configurations was studied. Two mirror support configurations were investigated for the Ames concept, the first employs a six-strut secondary mirror support structure, while the second uses a triple-bipod support design. All three configurations were modeled using a tetrahedral truss design for the primary mirror support structure. Response resulting from secondary mirror chopping was obtained for the two Ames configurations, and the response of the primary mirror from slewing was obtained for all three configurations.

Calleson, Robert E.↗
NASA NTRS1996

Lightweight, Thermally Insulating Structural Panels

Lightweight, thermally insulating panels that also serve as structural members developed. Honeycomb-core panel filled with low-thermal-conductivity, opacified silica aerogel preventing convection and minimizes internal radiation. Copper coating on face sheets reduces radiation. Overall thermal conductivities of panels smaller than state-of-art commercial non-structurally-supporting foam and fibrous insulations. On Earth, panels suitable for use in low-air-pressure environments in which lightweight, compact, structurally supporting insulation needed; for example, aboard high-altitude aircraft or in partially evacuated panels in refrigerators.

Eisen, Howard J.↗
NASA NTRS2008

Elastic Distribution of Microshutters, Measurements Obtainable on James Web Space Telescope

Spectrographic astronomy measurements in the near-infrared region will be done by functional two-dimensional microshutter arrays that are being fabricated at the NASA Goddard Space Flight Center for the James Webb Space Telescope (JWST). These micro-shutter arrays will represent the first mission-critical MEMS devices to be flown in space. JWST will use microshutter arrays to select focal plane object. 2-D programmable aperture masks of more than 200,000 elements select such space object. The use of silicon wafer material promises high efficiency and high contrast. Microshutter operation temperature is around 35K. Microshutter arrays are fabricated as close-packed silicon nitride membranes with a unit cell size of 105 x 204 micrometers. A layer of magnetic material is deposited onto each shutter. Individual shutters are equipped with a torsion flexure. Reactive ion etching (RIE) releases the shutters so they can open up to 90 degrees using the torsion flexure. Shutter rotation is initiated into a silicon support structure via an external magnetic field. Two electrically independent aluminum electrodes are deposited, one onto each shutter and another onto the support structure side-wall, permitting electrostatic latching and 2-D addressing to hold specific shutters open via external electronics.

Kletetschka, Gunther↗
NASA NTRS2019

System, Apparatus and Method for Pedal Control

An apparatus, method, and system for controlling motion in six degrees of freedom is described. The apparatus includes a support structure, a first pedal and a second pedal. A first set of three independent articulating mechanisms is operatively connected to the support structure and the first pedal. The first set of three independent articulating mechanisms, in combination, enable motion of the first pedal in three control axes corresponding to three discrete degrees of freedom. A second set of three independent articulating mechanisms, operatively connected to the second pedal, enable motion, in combination, in three control axes corresponding to a discrete second set of three degrees of freedom. The apparatus may also include first and second sensors configured to detect the motion of the first and second pedals.

Love, Stanley G.↗
NASA NTRS1990

Installing scientific instruments into a cold LHe dewar - The Gravity Probe B approach

Gravity Probe B is an orbital test of Einstein's general theory of relativity using gyroscopes. The precession of the gyroscopes will measure both the geodetic effect (6.6 arcsec/yr) through the curved space-time surrounding the earth and the motional effect (0.042 arcsec/yr) due to the rotating earth dragging space-time around with it. To achieve the extraordinary accuracies needed to measure these small precessions, it is necessary to have the gyroscopes operating in the following environments: a vacuum of less than 10 exp -10 torr; an acceleration level of less than 10 exp -10 g's; a magnetic field of less than 10 exp -7 gauss; and a temperature near 2 K. This paper discusses designs that allow scientific instruments to be installed into a dewar at 4.2 K. Methods for structurally supporting the instruments, transferring heat across joints at low temperature in vacuum, and excluding air during the insertion process are discussed. The structural support method is designed for Shuttle launch loads.

Parmley, Richard T.↗
NASA NTRS2002

Design, Development, and Integration of A Space Shuttle Orbiter Bay 13 Payload Carrier

Bay 13 of the Space Shuttle Orbiter has been limited to small sidewall mounted payloads and ballast. In order to efficiently utilize this space, a concept was developed for a cross-bay cargo carrier to mount Orbital Replacement Units (ORU's) for delivery to the International Space Station and provide additional opportunities for science payloads, while meeting the Orbiter ballast requirements. The Lightweight Multi-Purpose Experiment Support Structure (MPESS) Carrie (LMC) was developed and tested by NASA's Marshall Space Flight Center and the Boeing Company. The Multi-Purpose Experiment Support Structure (MPESS), which was developed for the Spacelab program was modified, removing the keel structure and relocating the sill trunnions to fit in Bay 13. Without the keel fitting, the LMC required a new and innovative concept for transferring Y loads into the Orbiter structure. Since there is no keel fitting available in the Bay 13 location, the design had to utilize the longeron bridge T-rail to distribute the Y loads. This concept has not previously been used in designing Shuttle payloads. A concept was developed to protect for Launch-On-Need ORU's, while providing opportunities for science payloads. Categories of potential ORU's were defined, and Get-Away Special (GAS) payloads of similar mass properties were provided by NASA's Goddard Space Flight Center. Four GAS payloads were manifest as the baseline configuration, preserving the capability to swap up to two ORU's for the corresponding science payloads, after installation into the Orbiter cargo bay at the pad, prior to closeout. Multiple configurations were considered for the analytical integration, to protect for all defined combinations of ORU's and GAS payloads. The first physical integration of the LMC war performed by Goddard Space Flight Center and Kennedy Space Center at an off-line facility at Kennedy Space Center. This paper will discuss the design challenges, structural testing, analytical and physical integration for the LMC's successful maiden flight on STS-108/ISS UF-1 mission in December 2001.

Spencer, Susan H.↗
NASA NTRS1998

Experimental flight test vibration measurements and nondestructive inspection on a USCG HC-130H aircraft

This paper presents results of experimental flight test vibration measurements and structural inspections performed by the Federal Aviation Administration's Airworthiness Assurance NDI Validation Center (AANC) at Sandia National Laboratories and the US Coast Guard Aircraft Repair and Supply Center (ARSC). Structural and aerodynamic changes induced by mounting a Forward Looking Infrared (FLIR) system on a USCG HC-130H aircraft are described. The FLIR adversely affected the air flow characteristics and structural vibration on the external skin of the aircraft's right main wheel well fairing. Upon initial discovery of skin cracking and visual observation of skin vibration in flight by the FLIR, a baseline flight without the FLIR was conducted and compared to other measurements with the FLIR installed. Nondestructive inspection procedures were developed to detect cracks in the skin and supporting structural elements and document the initial structural condition of the aircraft. Inspection results and flight test vibration data revealed that the FLIR created higher than expected flight loading and was the possible source of the skin cracking. The Coast Guard performed significant structural repair and enhancement on this aircraft, and additional in-flight vibration measurements were collected on the strengthened area both with and without the FLIR installed. After three months of further operational FLIR usage, the new aircraft skin with the enhanced structural modification was reinspected and found to be free of flaws. Additional US Coast Guard HC-130H aircraft are now being similarly modified to accommodate this FLIR system. Measurements of in- flight vibration levels with and without the FLIR installed, and both before and after the structural enhancement and repair were conducted on the skin and supporting structure in the aircraft's right main wheel fairing. Inspection results and techniques developed to verify the aircraft's structural integrity are discussed.

US COAST GUARD↗
DOE OSTI2022

Interpreting the Operando X-ray Absorption Near-Edge Structure of Supported Cu and CuPd Clusters in Conditions of Oxidative Dehydrogenation of Propane: Dynamic Changes in Composition and Size

Supported subnano-cluster catalysts are highly dynamic, developing true active sites only under the pressures and temperatures of reaction conditions. Operando X-ray absorption near-edge structure (XANES) spectroscopy can track changes in the oxidation state and the local environment of cluster atoms, providing insight into the development of these active sites. While bulk metal, oxide, and hydroxide standards are often used for fitting experimental XANES spectra to obtain average oxidation states, we recently showed that computed cluster standards of relevant compositions are a more suitable basis, producing more accurate fits. Here, we theoretically interpret the operando XANES of supported Cu 3 Pd and Cu 4 clusters during temperature-programmed reaction (TPRx) of oxidative dehydrogenation of propane. We use an expanded basis set including both globally optimized computed clusters and bulk standards. Not only can we track reversible composition/oxidation state change with temperature, but also the irreversible growth of the bulk fraction upon heating, which we attribute to cluster sintering. This has important implications for the mechanism of the catalyzed reaction and the nature of the available active sites. Here, we propose that operando XANES provides most significant insight into the nature of supported cluster catalysts in reaction conditions when interpreted using mixed computed cluster and bulk standards.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2015

Multi-Shock Shield Performance at 15 MJ for Catalogued Debris

While orbital debris of ten centimeters or more are tracked and catalogued, the difficulty of finding and accurately accounting for forces acting on the objects near the ten centimeter threshold results in both uncertainty of their presence and location. These challenges result in difficult decisions for operators balancing potential costly operational approaches with system loss risk. In this paper, the assessment of the feasibility of protecting a spacecraft from this catalogued debris is described using numerical simulations and a test of a multi-shock shield system against a cylindrical projectile impacting normal to the surface with approximately 15 MJ of kinetic energy. The hypervelocity impact test has been conducted at the Arnold Engineering Development Complex (AEDC) with a 598 g projectile at 6.905 km/s on a NASA supplied multi-shock shield. The projectile used is a hollow aluminum and nylon cylinder with an outside diameter of 8.6 cm and length of 10.3 cm. Figure 1 illustrates the multi-shock shield test article, which consisted of five separate bumpers, four of which are fiberglass fabric and one of steel mesh, and two rear walls, each consisting of Kevlar fabric. The overall length of the test article was 2.65 m. The test article was a 5X scaled-up version of a smaller multi-shock shield previously tested using a 1.4 cm diameter aluminum projectile for an inflatable module project. The distances represented by S1 and S1/2 in the figure are 61 cm and 30.5 cm, respectively. Prior to the impact test, hydrodynamic simulations indicated that some enhancement to the standard multi-shock system is needed to address the effects of the cylindrical shape of the projectile. Based on the simulations, a steel mesh bumper has been added to the shield configuration to enhance the fragmentation of the projectile. The AEDC test occurred as planned, and the modified NASA multi-shock shield successfully stopped 598 g projectile using 85.6 kg/m(exp 2). The fifth bumper layer remained in tact, although it was torn free from its support structure and thrown into the first rear wall. The outer Kevlar layer of the first rear wall tore likely from the impact of the fifth bumper's support structure, but the back of the rear wall was intact. No damage occurred to the second rear wall, or to the witness plate behind the target.

Miller, J. E.↗
NASA NTRS1982

Offset wrap rib antenna concept development

The demonstration of 50 to 150 m, STS compatible, offset antenna technology readiness is reported. Fabrication of a ground and flight testable partial 55 m reflector section and feed support structure is discussed. Reduction to practice through ground test verification is presently contained in the program. Key objectives for the program include the design of a compatible feed support structure and the fabrication and testing of critical components.

Woods, A. A., Jr.↗
DOE OSTI2023

Wind Loading on Parabolic Trough Collectors: Wind and Structural Loads Measurements at an Operational Powerplant

Concentrated Solar Power (CSP) is a promising method for using solar power for electricity generation with thermal energy storage for industrial applications. Solar collectors constitute almost 1/3 of the total cost of the power plant. One of the primary drivers of unrealiability of these collectors is wind-driven loading of mirrors, support structures, and drives. To date, the design of the solar collector structures has relied on data from wind tunnels that do not adequately capture the dynamic effects observed at scale. NREL initiated a field measurement campaign at the operational Nevada Solar One (NSO) parabolic trough powerplant. At this plant, parabolic trough solar collectors track the sun from east to west in the course of a day and face varying wind loads depending on the wind properties and the angle of the troughs. The aim of the project is a detailed characterization of prevailing wind and turbulence conditions and resulting operational loads on parabolic troughs, providing insights into structural dynamic response, and generating a comprehensive wind-loading dataset for validating simulations of wind loading on collector structures. The measurements at NSO consist of sonic anemometers on masts at different heights to characterize the incoming flow and conditions at four trough rows at the edge of the trough field. In addition, a Doppler Lidar scans the horizontal plane above the troughs. The wind measurements at NSO have been continuously collecting data since October 2021 and are combined with structural load measurements that started in November 2022. The load measurements were installed on the same four outermost trough rows and include support structure bending moments, drive torque moments, dynamic accelerations of the spaceframe, mirror displacement, and tilt angles. Measurements are planned to continue until May 2023, providing a first-of-a-kind, high-resolution multi-month dataset of combined wind and load measurements. In this presentation, we show first results of the measurement campaign. Based on the measurements, we identified three main factors altering the flow over the parabolic troughs: Wind speed, wind direction, and the angle of the parabolic troughs. Most interactions between incoming wind and the trough field are observed when the wind blows perpendicular to the trough rows. In this case, the first rows experience the highest wind speed and block the downwind rows, creating conditions with decreased wind speed and enhanced turbulence within the trough field. Also, turbulent length scales are smaller after the first row. This leads to the highest static loads (bending and torque moments) at the first row but potentially increased dynamic loads within the field. We illustrate our findings with case studies focused on different wind conditions and will present fatigue analysis to highlight the impact of wind-driven loads on collector structures.

CSP collectors↗
NASA NTRS2020

Repair of Sandwich Structure in Support of the Payload Adapter Fitting (PAF) Part II: Severe Damage Repair

As part of a program examining a Payload Adaptor Fitting (PAF) for NASA’s Space Launch System (SLS), a repair study of impact damage and misdrilled holes in composite sandwich structure was undertaken.1 In that study, it was shown that small holes and barely visible impact damage (BVID) could be repaired and all the measured undamaged in-plane compression strength recovered without removing the damaged material using a simple patch repair. It was noted that for more severe damage, either larger patches or removal of damage (or both) may be necessary to regain all of the measured undamaged compression strength. This Technical Memorandum (TM) presents the results of an experimental investigation into repair of more severely damaged sandwich structure than what was studied in reference 1.

Nettles, A. T.↗