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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS2015

Design Process of Flight Vehicle Structures for a Common Bulkhead and an MPCV Spacecraft Adapter

Design and manufacturing space flight vehicle structures is a skillset that has grown considerably at NASA during that last several years. Beginning with the Ares program and followed by the Space Launch System (SLS); in‐house designs were produced for both the Upper Stage and the SLS Multipurpose crew vehicle (MPCV) spacecraft adapter. Specifically, critical design review (CDR) level analysis and flight production drawing were produced for the above mentioned hardware. In particular, the experience of this in‐house design work led to increased manufacturing infrastructure for both Marshal Space Flight Center (MSFC) and Michoud Assembly Facility (MAF), improved skillsets in both analysis and design, and hands on experience in building and testing (MSA) full scale hardware. The hardware design and development processes from initiation to CDR and finally flight; resulted in many challenges and experiences that produced valuable lessons. This paper builds on these experiences of NASA in recent years on designing and fabricating flight hardware and examines the design/development processes used, as well as the challenges and lessons learned, i.e. from the initial design, loads estimation and mass constraints to structural optimization/affordability to release of production drawing to hardware manufacturing. While there are many documented design processes which a design engineer can follow, these unique experiences can offer insight into designing hardware in current program environments and present solutions to many of the challenges experienced by the engineering team.

Aggarwal, Pravin↗
NASA NTRS2015

Adjustable Grazing-Incidence X-Ray Optics

With its unique subarcsecond imaging performance, NASA's Chandra X-ray Observatory illustrates the importance of fine angular resolution for x-ray astronomy. Indeed, the future of x-ray astronomy relies upon x-ray telescopes with comparable angular resolution but larger aperture areas. Combined with the special requirements of nested grazing-incidence optics, mass, and envelope constraints of space-borne telescopes render such advances technologically and programmatically challenging. The goal of this technology research is to enable the cost-effective fabrication of large-area, lightweight grazing-incidence x-ray optics with subarcsecond resolution. Toward this end, the project is developing active x-ray optics using slumped-glass mirrors with thin-film piezoelectric arrays for correction of intrinsic or mount-induced distortions.

O'Dell, Stephen L.↗
NASA NTRS2016

Toward Large-Area Sub-Arcsecond X-Ray Telescopes II

In order to advance significantly scientific objectives, future x-ray astronomy missions will likely call for x-ray telescopes with large aperture areas (approx. = 3 sq m) and fine angular resolution (approx. = 1"). Achieving such performance is programmatically and technologically challenging due to the mass and envelope constraints of space-borne telescopes and to the need for densely nested grazing-incidence optics. Such an x-ray telescope will require precision fabrication, alignment, mounting, and assembly of large areas (approx. = 600 sq m) of lightweight (approx. = 2 kg/sq m areal density) high-quality mirrors, at an acceptable cost (approx. = 1 M$/sq m of mirror surface area). This paper reviews relevant programmatic and technological issues, as well as possible approaches for addressing these issues-including direct fabrication of monocrystalline silicon mirrors, active (in-space adjustable) figure correction of replicated mirrors, static post-fabrication correction using ion implantation, differential erosion or deposition, and coating-stress manipulation of thin substrates.

Shi Ye↗
NASA NTRS2010

Propulsion Design With Freeform Fabrication (PDFF)

The nation is challenged to decrease the cost and schedule to develop new space transportation propulsion systems for commercial, scientific, and military purposes. Better design criteria and manufacturing techniques for small thrusters are needed to meet current applications in missile defense, space, and satellite propulsion. The requirements of these systems present size, performance, and environmental demands on these thrusters that have posed significant challenges to the current designers and manufacturers. Designers are limited by manufacturing processes, which are complex, costly, and time consuming, and ultimately limited in their capabilities. The PDFF innovation vastly extends the design opportunities of rocket engine components and systems by making use of the unique manufacturing freedom of solid freeform rapid prototype manufacturing technology combined with the benefits of ceramic materials. The unique features of PDFF are developing and implementing a design methodology that uses solid freeform fabrication (SFF) techniques to make propulsion components with significantly improved performance, thermal management, power density, and stability, while reducing development and production costs. PDFF extends the design process envelope beyond conventional constraints by leveraging the key feature of the SFF technique with the capability to form objects with nearly any geometric complexity without the need for elaborate machine setup. The marriage of SFF technology to propulsion components allows an evolution of design practice to harmonize material properties with functional design efficiency. Reduced density of materials when coupled with the capability to honeycomb structure used in the injector will have significant impact on overall mass reduction. Typical thrusters in use for attitude control have 60 90 percent of its mass in the valve and injector, which is typically made from titanium. The combination of material and structure envisioned for use in an SFF thruster design could reduce thruster weight by a factor of two or more. The thrust-to-weight ratios for such designs can achieve 1,000:1 or more, depending on chamber pressure. The potential exists for continued development in materials, size, speed, accuracy of SFF techniques, which can lead to speculative developments of PDFF processes such as fabrication of custom human interface devices like masks, chairs, and clothing, and advanced biomedical application to human organ reconstruction. Other potential applications are: higher fidelity lower cost test fixtures for probes and inspection, disposable thrusters, and ISRU (in situ resource utilization) for component production in space or on Lunar and Martian missions, and application for embedding MEMS (microelectromechanical systems) during construction process of form changing aerostructure/dynamic structures.

Barnes, Daudi↗
DOE OSTI2022

Machine learning with knowledge constraints for process optimization of open-air perovskite solar cell manufacturing

Perovskite photovoltaics (PV) have achieved rapid development in the past decade in terms of power conversion efficiency of small-area lab-scale devices; however, successful commercialization still requires further development of low-cost, scalable, and high-throughput manufacturing techniques. One of the critical challenges of developing a new fabrication technique is the high-dimensional parameter space for optimization, but machine learning (ML) can readily be used to accelerate perovskite PV scaling. Herein, we present an ML-guided framework of sequential learning for manufacturing process optimization. We apply our methodology to the Rapid Spray Plasma Processing (RSPP) technique for perovskite thin films in ambient conditions. With a limited experimental budget of screening 100 process conditions, we demonstrated an efficiency improvement to 18.5% as the best-in-our-lab device fabricated by RSPP, and we also experimentally found 10 unique process conditions to produce the top-performing devices of more than 17% efficiency, which is 5 times higher rate of success than the control experiments with pseudo-random Latin hypercube sampling. Our model is enabled by three innovations: (a) flexible knowledge transfer between experimental processes by incorporating data from prior experimental data as a probabilistic constraint; (b) incorporation of both subjective human observations and ML insights when selecting next experiments; (c) adaptive strategy of locating the region of interest using Bayesian optimization first, and then conducting local exploration for high-efficiency devices. Furthermore, in virtual benchmarking, our framework achieves faster improvements with limited experimental budgets than traditional design-of-experiments methods (e.g., one-variable-at-a-time sampling). This framework shows the capability of incorporating researchers’ domain knowledge into the ML-guided optimization loop; therefore, it has the potential to facilitate the wider adoption of ML in scaling to perovskite PV manufacturing.

14 SOLAR ENERGY↗
NASA NTRS1979

Development of crashworthy passenger seats for general-aviation aircraft

Two types of energy absorbing passenger seat concepts suitable for installation in light twin-engine fixed wing aircraft were developed. An existing passenger seat for such an aircraft was used to obtain the envelope constraints. Ceiling suspended and floor supported seat concept designs were developed. A restraint system suitable for both concepts was designed. Energy absorbing hardware for both concepts was fabricated and tension and compression tests were conducted to demonstrate the stroking capability and the force deflection characteristics. Crash impact analysis was made and seat loads developed. The basic seat structures were analyzed to determine the adequacy of their strength under impact loading.

Reilly, M. J.↗
NASA NTRS2016

Silicon Micromachined Modulated Metasurface Antennas in the Terahertz Range

This paper explores the capabilities of a class of metasurface (MTS), which consists of metalized cylinders on a ground plane, for the realization of modulated MTS antennas at terahertz (THz) frequencies. The proposed structure is particularly appropriate for being micromachined out of a silicon wafer by means of deep reactive ion etching (DRIE). The constraints that DRIE imposes in the design of the MTS unit cell are discussed, along with the advantages of silicon micromachined modulated MTSs with respect to other fabrication approaches in the THz range.

deep-reactive ion etching↗
NASA NTRS2020

Hybrid AFP/Hand Layup Optimized Blades to Enhance Wind Tunnel Capability Summary of PREDICT 2018 Efforts

A project spanning four-months in 2018 was conducted at the NASA Langley Research Center (LaRC) to advance the state of the art in Automated Fiber Placement (AFP) fabrication of complex carbon fiber wind tunnel blades for NASA wind tunnels. This effort was the first step in developing a methodology for fabricating these complex parts. An AFP robotic system was used to explore whether manufacturing time and cost for production of wind tunnel blades could be reduced. Computer aided design models of the blade surfaces were created, and AFP process planning and programming was employed to study the manufacturability of the shapes. A manufacturing demonstration unit was fabricated to demonstrate a methodology to fabricate a complex shape representative of a wind tunnel blade. The present study revealed that the heater configuration on the LaRC AFP robotic system was the primary constraint that limited its ability to use AFP for wind tunnel blade manufacturing.

carbon-epoxy↗
DOE OSTI2020

Poly(lactic acid)-Based Ink for Biodegradable Printed Electronics With Conductivity Enhanced through Solvent Aging

Biodegradable electronics is a rapidly growing field, and the development of controllably biodegradable, high-conductivity materials suitable for additive manufacturing under ambient conditions remains a challenge. Here, printable conductive pastes that employ poly(lactic acid) (PLA) as a binder and tungsten as a conductor are demonstrated. These composite conductors can provide enhanced stability in applications where moisture may be present, such as environmental monitoring or agriculture. Post-processing the printed traces using a solvent-aging technique increases their conductivity by up to 2 orders of magnitude, with final conductivities approaching 5000 S/m. Such techniques could prove useful when thermal processes including heating or laser sintering are limited by the temperature constraints of typical biodegradable substrates. Finally, both accelerated oxidative and hydrolytic degradation of the printed composite conductors are examined, and a fully biodegradable capacitive soil moisture sensor is fabricated and tested.

36 MATERIALS SCIENCE↗
NASA NTRS1993

Laser-based firing systems for prompt initiation of secondary explosives

Motivated by issues of weapon safety and security, laser based firing systems for promptly initiating secondary explosives have been under active development at Sandia National Laboratories for more than four years. Such a firing system consists of miniaturized, Q-switched, solid-state laser, optical detonators, optical safety switches, and elements for splitting, coupling, and transmitting the laser output. Potential system applications pose significant challenges in terms of server mechanical and thermal environments and packaging constraints, while requiring clear demonstration of safety enhancements. The Direct Optical Initiation (DOI) Program at Sandia is addressing these challenges through progress development phases during which the design, fabrication, and testing of prototype hardware is aimed at more difficult application requirements. A brief history of the development program, and a summary of current and planned activities, will be presented.

Meeks, Kent D.↗
NASA NTRS1987

Advanced radiator concepts utilizing honeycomb panel heat pipes

The feasibility of fabricating and processing moderate temperature range vapor chamber type heat pipes in a low mass honeycomb panel configuration for highly efficient radiator fins for potential use on the space station was investigated. A variety of honeycomb panel facesheet and core-ribbon wick concepts were evaluated within constraints dictated by existing manufacturing technology and equipment. Concepts evaluated include type of material, material and panel thickness, wick type and manufacturability, liquid and vapor communication among honeycomb cells, and liquid flow return from condenser to evaporator facesheet areas. A thin-wall all-welded stainless steel design with methanol as the working fluid was the initial prototype unit. It was found that an aluminum panel could not be fabricated in the same manner as a stainless steel panel due to diffusion bonding and resistance welding considerations. Therefore, a formed and welded design was developed. The prototype consists of ten panels welded together into a large panel 122 by 24 by 0.15 in., with a heat rejection capability of 1000 watts and a fin efficiency of essentially 1.0.

Fleischman, G. L.↗
NASA NTRS1993

A Microseismometer for Terrestrial and Extraterrestrial Applications

The scientific and technical requirements of extraterrestrial seismology place severe demands on instrumentation. Performance in terms of sensitivity, stability, and frequency band must match that of the best terrestrial instruments, at a fraction of the size, mass, and power. In addition, this performance must be realized without operator intervention in harsh temperature, shock, and radiation environments. These constraints have forced us to examine some fundamental limits of accelerometer design in order to produce a small, rugged, sensitive seismometer. Silicon micromachined sensor technology offers techniques for the fabrication of monolithic, robust, compact, low-power and -mass accelerometers. However, currently available sensors offer inadequate sensitivity and bandwidth. Our implementation of an advanced silicon micro machined seismometer is based on principles developed at JPL for high-sensitivity position sensor technology. The use of silicon micro machining technology with these new principles should enable the fabrication of a 10(exp -11) g sensitivity seismometer with a bandwidth of at least 0.01 to 20 Hz. The low Q properties of pure single-crystal silicon are essential in order to minimize the Brownian thermal noise limitations generally characteristic of seismometers with small proof masses. A seismometer consists of a spring-supported proof mass and a transducer for measuring its motion. For long period motion a position sensor is generally used, for which the displacement is proportional to the ground acceleration. The mechanical sensitivity can be increased either by increasing the proof mass or decreasing the spring stiffness, neither of which is desirable for planetary applications. Our approach has been to use an ultra sensitive capacitive position sensor with a sensitivity of better than 10(exp -13) m/Hz(exp 1/2). This allows the use of a stiffer suspension and a smaller proof mass. We have built several prototypes using these principles, and tests show that these devices can exhibit performance comparable to state-of-the-art instruments.

Banerdt, W.↗
NASA NTRS2017

Computational Assessment of a 3-Stage Axial Compressor Which Provides Airflow to the NASA 11- by 11-Foot Transonic Wind Tunnel, Including Design Changes for Increased Performance

A 24 foot diameter 3-stage axial compressor powered by variable-speed induction motors provides the airflow in the closed-return 11- by 11-Foot Transonic Wind Tunnel (11-Foot TWT) Facility at NASA Ames Research Center at Moffett Field, California. The facility is part of the Unitary Plan Wind Tunnel, which was completed in 1955. Since then, upgrades made to the 11-Foot TWT such as flow conditioning devices and instrumentation have increased blockage and pressure loss in the tunnel, somewhat reducing the peak Mach number capability of the test section. Due to erosion effects on the existing aluminum alloy rotor blades, fabrication of new steel rotor blades is planned. This presents an opportunity to increase the Mach number capability of the tunnel by redesigning the compressor for increased pressure ratio. Challenging design constraints exist for any proposed design, demanding the use of the existing driveline, rotor disks, stator vanes, and hub and casing flow paths, so as to minimize cost and installation time. The current effort was undertaken to characterize the performance of the existing compressor design using available design tools and computational fluid dynamics (CFD) codes and subsequently recommend a new compressor design to achieve higher pressure ratio, which directly correlates with increased test section Mach number. The constant cross-sectional area of the compressor leads to highly diffusion factors, which presents a challenge in simulating the existing design. The CFD code APNASA was used to simulate the aerodynamic performance of the existing compressor. The simulations were compared to performance predictions from the HT0300 turbomachinery design and analysis code, and to compressor performance data taken during a 1997 facility test. It was found that the CFD simulations were sensitive to endwall leakages associated with stator buttons, and to a lesser degree, under-stator-platform flow recirculation at the hub. When stator button leakages were modeled, pumping capability increased by over 20 of pressure rise at design point due to a large reduction in aerodynamic blockage at the hub. Incorporating the stator button leakages was crucial to matching test data. Under-stator-platform flow recirculation was thought to be large due to a lack of seals. The effect of this recirculation was assessed with APNASA simulations recirculating 0.5, 1, and 2 of inlet flow about stators 1 and 2, modeled as axisymmetric mass flux boundary conditions on the hub before and after the vanes. The injection of flow ahead of the stators tended to re-energize the boundary layer and reduce hub separations, resulting in about 3 increased stall margin per 1 of inlet flow recirculated. In order to assess the value of the flow recirculation, a mixing plane simulation of the compressor which gridded the under-stator cavities was generated using the ADPAC CFD code. This simulation indicated that about 0.65 of the inlet flow is recirculated around each shrouded stator. This collective information was applied during the redesign of the compressor. A potential design was identified using HT0300 which improved overall pressure ratio by removing pre-swirl into rotor 1, replacing existing NASA 65 series rotors with double circular arc sections, and re-staggering rotors and the existing stators. The performance of the new design predicted by APNASA and HT0300 is compared to the existing design.

Turbomachinery↗
NASA NTRS2010

Corrosion-Resistant Container for Molten-Material Processing

In a carbothermal process, gaseous methane is passed over molten regolith, which is heated past its melting point to a temperature in excess of 1,625 C. At this temperature, materials in contact with the molten regolith (or regolith simulant) corrode and lose their structural properties. As a result, fabricating a crucible to hold the molten material and providing a method of contact heating have been problematic. Alternative containment approaches use a large crucible and limit the heat zone of the material being processed, which is inefficient because of volume and mass constraints. Alternative heating approaches use non-contact heating, such as by laser or concentrated solar energy, which can be inefficient in transferring heat and thus require higher power heat sources to accomplish processing. The innovation is a combination of materials, with a substrate material having high structural strength and stiffness and high-temperature capability, and a coating material with a high corrosion resistance and high-temperature capability. The material developed is a molybdenum substrate with an iridium coating. Creating the containment crucible or heater jacket using this material combination requires only that the molybdenum, which is easily processed by conventional methods such as milling, electric discharge machining, or forming and brazing, be fabricated into an appropriate shape, and that the iridium coating be applied to any surfaces that may come in contact with the corrosive molten material. In one engineering application, the molybdenum was fashioned into a container for a heat pipe. Since only the end of the heat pipe is used to heat the regolith, the container has a narrowing end with a nipple in which the heat pipe is snugly fit, and the external area of this nipple, which contacts the regolith to transfer heat into it, is coated with iridium. At the time of this reporting, no single material has been found that can perform the functions of this combination of materials, and other combinations of materials have not proven to be survivable to the corrosiveness of this environment. High-temperature processing of materials with similar constituencies as lunar regolith is fairly common. The carbo-thermal process is commonly used to make metallurgical-grade silicon for the semiconductor and solar-cell industries.

Stern, Theodore G.↗
NASA NTRS1973

Design, fabrication, and performance of foil journal bearing for the brayton rotating unit

Foil bearings were designed and manufactured to replace pivoted-shoe journal bearings in an existing Brayton Cycle turbo-alternator-compressor. The design of this unconventional rotor support was accomplished within the constraints and space limitations imposed by the present machine, and the substitution of foil bearings was effected without changes or modification other machine components. A housing and a test rig were constructed to incorporate the new foil-bearing support into a unified assemble with an air-driven rotor and the gimbal-mounted thrust bearing, seals, and shrouds of an actual Brayton Rotating Unit. The foil bearing required no external pressure source, and stable self-acting rotation was achieved at all speeds up to 43,200 rpm. Excellent wipe-wear characteristics of the foil bearing permitted well over 1000 start-stop cycles with no deterioriation of performance in the entire speed range.

Licht, L.↗
NASA NTRS1978

Study of low-cost fabrication methods for aerospace composite materials

Flat and hat section specimens of graphite/epoxy composite materials have been fabricated by the resin bath or wet pultrusion process. This demonstrated the feasibility of incorporating crossplied graphite fiber reinforcements in conjunction with epoxy resin systems in the wet pultrusion process. However, the thickness constraints of the pultrusion process, the lack of dimensional stability of the crossply materials and equipment limitations affect the quality of the hat section pultrusions. The wet pultrusion process shows promise of being a low cost method for producing composite parts with constant cross section along the length. A cost analysis showed at least 80 percent cost reduction for the hat section and 40 percent for flat panel by pultrusion over the conventional manual and automated lay-up.

Chung, H. H.↗
NASA NTRS1994

Optical surface contouring for non-destructive inspection of turbomachinery

Detection of stress cracks and other surface defects during maintenance and in-service inspection of propulsion system components, including turbine blades and combustion compartments, is presently performed visually. There is a need for a non-contact, miniaturized, and fully fieldable instrument that may be used as an automated inspection tool for inspection of aircraft engines. During this SBIR Phase 1 program, the feasibility of a ruggedized optical probe for automatic and nondestructive inspection of complex shaped objects will be established. Through a careful analysis of the measurement requirements, geometrical and optical constraints, and consideration of issues such as manufacturability, compactness, simplicity, and cost, one or more conceptual optical designs will be developed. The proposed concept will be further developed and a prototype will be fabricated during Phase 2.

Modarress, Dariush↗
NASA NTRS2007

Larger, Lighter Space Telescopes by Implementing In-Space Manufacturing Concepts

There is a continuous demand for larger, lighter, and higher quality telescopes from both the astronomical and global surveillance communities one looking up and the other down. Enabling technologies must be developed and implemented that will allow this goal to be financially and technically feasible. The optical systems needed far high spatial resolution surveillance and astronomical applications require large optical, apertures with mention of future systems up to 150 meter in diameter. With traditional optical manufacturing technologies, large optical aperture means high mass and long fabrication lead times with associated high costs. Completely new approaches to optical fabrication must be developed to enable the fabrication of such optical systems. The cost and lead time associated with the fabrication of lightweight, high quality optical systems limits the feasible size of the optics. A primary factor in the launch cost of space optical systems is volume and mass. To minimize the mass of the high quality optics, optical fabricators implement materials with high specific stiffness and use honeycomb, or other structural minimization patterns, to support the optical surface; however, the structure must still be designed to survive launch loads. This sigmficantly adds to the fabrication difficulty and dramatically increases launch costs. One approach to minimizing launch volume and negating the need for the design to survive launch loads is to send the manufacturing facility and raw materials into space and perform the fabrication in-situ. We, are currently performing feasibility studies of initial concepts for inspace manufacturing of optical systems. By utilizing the micro-gravity and vacuum environment of space while eliminating the constraints defined by high launch forces and limited volume of the launch vehicle, the development of large, high quality glass membrane mirrors may be feasible. Several concepts were investigated to address the manufacturing of both optical surfaces and telescope structure. We will describe one of the primary approaches to utilize the space environment for optical manufacturing and describe initial results.

Mooney, James t.↗