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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Fracture analysis of surface and through-cracks in cylindrical pressure vessels

A previously developed fracture criterion was applied to surface- and through-cracked cylindrical pressure vessels to see how well the criterion can correlate fracture data. Fracture data from the literature on surface cracks in aluminum alloy, steel, and epoxy vessels and on through cracks in aluminum alloy, titanium alloy, steel, and brass vessels were analyzed using the fracture criterion. The criterion correlated the failure stresses to within + or - 10 percent for either surface or through cracks over a wide range of crack size and vessel diameter. The fracture criterion was also found to correlate failure stresses from flat plates (center-crack or double-edge-crack tension specimens) and cylindrical pressure vessels containing through - cracks within + or - 10 percent.

Newman, J. C., Jr.↗
NASA NTRS1977

Considerations for acoustic emission monitoring of spherical Kevlar/epoxy composite pressure vessels

We are continuing to research the applications of acoustic emission testing for predicting burst pressure of filament-wound Kevlar 49/epoxy pressure vessels. This study has focused on three specific areas. The first area involves development of an experimental technique and the proper instrumentation to measure the energy given off by the acoustic emission transducer per acoustic emission burst. The second area concerns the design of a test fixture in which to mount the composite vessel so that the acoustic emission transducers are held against the outer surface of the composite. Included in this study area is the calibration of the entire test setup including couplant, transducer, electronics, and the instrument measuring the energy per burst. In the third and final area of this study, we consider the number, location, and sensitivity of the acoustic emission transducers used for proof testing composite pressure vessels.

Hamstad, M. A.↗
NASA NTRS1996

Performance features of 22-cell, 19Ah single pressure vessel nickel hydrogen battery

Two 22-cells 19Ah Nickel-Hydrogen (Ni-H2) Single Pressure Vessel (SPV) Qual batteries, one each from EPI/Joplin and EPI/Butler, were designed and procured. The two batteries differ in the cell encapsulation technology, stack preload, and activation procedure. Both the Butler and Joplin batteries met the specified requirements when subjected to qualification testing and completed 2100 and 1300 LEO cycles respectively, with nominal performance. This paper discusses advantages, design features, testing procedures, and results of the two single pressure vessel Ni-H2 batteries.

Rao, Gopalakrishna M.↗
NASA NTRS1971

High performance filament wound composites for pressure vessel applications.

A new high modulus fiber was evaluated as a reinforcement for filament wound pressure vessels. Based on preliminary data it offers significant specific strength and modulus improvements over an S-glass reinforcement. Winding parameters and design data were established for the fiber with two different epoxy resin systems. NOL composite rings were evaluated for tensile strength, modulus and interlaminar shear strength at +70 F, -320 F and -423 F. Results showed that the fiber reinforced composite exhibited a specific strength of 4,100,000 inches and a specific modulus of 290,000,000 inches compared to 3,260,000 inches and 110,000,000 inches respectively for S-glass. Utilizing this data to design small filament wound pressure vessels, a performance factor of 806,000 inches was obtained experimentally with PRD 49-1 fiber compared to values of 632,000 inches and 501,000 inches for S-glass and high modulus graphite vessels, respectively.

Hoggatt, J. T.↗
NASA NTRS1975

Fatigue life of organic fiber/epoxy pressure vessels

The cyclic fatigue life of 10.2-cm-diam cylindrical pressure vessels has been studied. The vessels were made of an organic fiber/epoxy composite. To determine the typical strength distribution of the vessels, 25 of them were internally pressurized until they burst. Twenty-five vessels were then tested under sinusoidal cycling at 1 Hz between 4% and 91% of the mean burst strength. An additional twenty-five vessels were tested between 4% and 91% with a rectangular pressure pulse at 1/3 Hz. A limited number of vessels were tested for stress rupture at the 91% level. Cyclic life was found to depend on time at peak load as well as the number of stress cycles.

Hamstad, M. A.↗
NASA NTRS2010

Composite Overwrapped Pressure Vessel (COPV) Stress Rupture Testing

This paper reports stress rupture testing of Kevlar(TradeMark) composite overwrapped pressure vessels (COPVs) at NASA White Sands Test Facility. This 6-year test program was part of the larger effort to predict and extend the lifetime of flight vessels. Tests were performed to characterize control parameters for stress rupture testing, and vessel life was predicted by statistical modeling. One highly instrumented 102-cm (40-in.) diameter Kevlar(TradeMark) COPV was tested to failure (burst) as a single-point model verification. Significant data were generated that will enhance development of improved NDE methods and predictive modeling techniques, and thus better address stress rupture and other composite durability concerns that affect pressure vessel safety, reliability and mission assurance.

Greene, Nathanael J.↗
NASA NTRS1973

Design Guide for glass fiber reinforced metal pressure vessel

Design Guide has been prepared for pressure vessel engineers concerned with specific glass fiber reinforced metal tank design or general tank tradeoff study. Design philosophy, general equations, and curves are provided for safelife design of tanks operating under anticipated space shuttle service conditions.

Landes, R. E.↗
NASA NTRS2022

Analysis of Base Metal Microstructures and Mechanical Properties of a Single-Piece, Spin-Formed Forward Pressure Vessel Bulkhead

In 2012, a pathfinder forward pressure vessel bulkhead (FPVBH) for the Orion Multi-Purpose Crew Vehicle (MPCV) was fabricated using aluminum (Al) alloy 2219. The demonstration article was offered as a replacement for the baseline configuration, which at that time was a multi-piece welded construction using aluminum-lithium (Al-Li) alloy 2195. In 2014, the NASA Engineering and Safety Center (NESC) funded a Phase I effort to explore spin-forming as a manufacturing method to produce a complex-shaped, single-piece FPVBH for the crew module (CM) [1]. The primary focus of the NESC effort was to expand spin-forming technology to the fabrication of an Al-Li 2195 FPVBH. As a result, limited testing and analysis was performed on the original Al 2219 article. In this study, a sufficiently large plate of Al 2219 was not available for the fabrication of a FPVBH. Therefore, the forming blank comprised two plates (from different lots) butt welded together using a single friction stir weld. The welded forming blank was then spin formed into the FPVBH configuration and heat treated to the T62 temper. Mechanical property testing of the spin-formed 2219-T62 FPVBH revealed that the tensile properties were comparable to the Metallic Material Properties Development and Standardization (MMPDS) A-basis allowable for Al 2219-T6 wrought products. However, post-spin forming application of the standard heat treatment produced large, recrystallized grains in the material. The response varied within the two plates; one plate lot exhibited nearly complete recrystallization, while the other lot contained bands of recrystallization. Although no reduction in tensile properties was observed due to these microstructural variations, a more detailed investigation was recommended to better understand the effect of spin forming on the recrystallization mechanism and the impact on other material properties. The current study examined the microstructure and mechanical properties of the fully processed Al 2219-T62 FPVBH with emphasis on comparing differences between the two plates. Testing was limited to the cone region of the FPVBH. The two specific tasks in this study were: a) Characterization of the microstructure and mechanical properties in the two plates used in the FPVBH. b) Isolation of the impact of each step in the thermo-mechanical processing (TMP) sequence of the FPVBH on recrystallization and grain growth. Mechanical property testing sampled regions containing both large, recrystallized and small, unrecrystallized grains. Tensile strengths and elongations were equivalent in both regions and exceeded MMPDS A-basis allowables. Fracture toughness was equivalent in both regions and fracture morphology was typical of aluminum alloys. The fatigue precrack region of the fracture toughness specimens appeared more faceted in the recrystallized plate. This suggests that property testing that is more sensitive to grain size, such as fatigue crack growth rate and stress corrosion cracking, may be warranted. Alcoa reviewed the production records for the two plate lots and confirmed that composition of both plates was within the allowable range for Al 2219 and that plate processing steps were all performed within production limits. However, the Fe content was notably higher in the fully recrystallized plate, resulting in a greater volume fraction of large Fe-bearing inclusions and Al-Cu constituent particles. Alcoa did not provide details regarding plate processing variables for the two plate lots. It was surmised that deformation by hot rolling was the most accurate TMP simulation of commercial spin forming within a laboratory setting. Both hot rolling and spin forming comprise combinations of shear and compressive deformation. The through-thickness strain caused by hot rolling is symmetrical about the mid-plane, as the rollers contact both sides of the material. Shear strains are maximum at the inner and outer surfaces and trend toward zero at the mid-thickness. In contrast, spin forming utilizes a single roller on the outer surface, producing a gradient in shear stress through the thickness. Shear strains in spin-formed material are highest at the outer surface due to direct contact with the roller, and trend toward zero at the inner surface. Consequently, there will undoubtedly be some discrepancies in the mechanical response of hot-rolled and spin-formed products in the through-thickness direction. Interrupted TMP simulations were performed on remnant plate from the FPVBH forming blank in order to isolate the effects of a post-weld anneal, spin-forming deformation/thermal cycling, and solution heat treatment (SHT) on development of the recrystallized microstructures. Analysis confirmed that large, recrystallized grains formed exclusively during SHT and only after a certain deformation level was exceeded. Remnant plate from both lots that received thermal processing only did not exhibit recrystallization but exhibited fully recrystallized microstructures when processed by hot rolling. This indicates that (1) the level of deformation exceeded the critical level for recrystallization in both plates and (2) that the level of deformation during hot rolling was greater than that which accumulated during spin forming of the FPVBH. Comparison of the hot-rolled plate with the spin-formed material showed that the recrystallized grain size was larger in the FPVBH, providing further evidence that deformation levels were lower in the FPVBH. The most plausible explanation for the differing degrees of recrystallization in the two plates is particle stimulated nucleation (PSN) at the Fe-bearing inclusions and large Al-Cu constituent particles. In the plate with higher solute content, the greater volume fraction of these particles reduces the deformation level required to promote recrystallization. During spin forming the critical deformation level was likely exceeded for the higher Fe content plate resulting in a fully recrystallized microstructure. The lower Fe content plate developed a microstructure that exhibited bands of recrystallization due to the combination of a non-uniform distribution of particles and deformation. The critical deformation required for recrystallization was likely only exceeded during spin forming in regions of higher particle content. While there were differences in Fe content between these lots of Al 2219 plate, the composition of both was within defined alloy limits and Alcoa reported no anomalies during plate production. The observed differences in recrystallization after spin forming may reflect the inherent variability between these two lots of plate. The spin-forming vendor, Spincraft, reported that similar variations in recrystallized microstructures have been observed during examination of multiple spin-forming trials of a different 2xxx series aluminum alloy. Hence, tighter chemical specification limits on impurity levels in Al 2219 plate may help ensure uniform, predictable microstructures. Finally, the tensile and fracture toughness properties were not affected by the microstructural variations noted.

single-piece↗
NASA NTRS1975

Fatigue performance of metal-lined graphite/epoxy pressure vessels

Using an ultrahigh-strength graphite fiber, a program was started to develop a thin metal-lined fiber/epoxy pressure vessel that would have a fatigue life of over 1000 cycles. First, the performance factor of the fiber/epoxy composite was found to be 351 kN m/kg from the average of 18 rubber-lined pressure vessels. Then, both aluminum- and titanium-lined vessels were filament wound with the graphite fiber in an epoxy matrix. Several of these metal-lined vessels were subjected to hydraulic fatigue testing to about 50% of their expected burst pressures. The average fatigue life of the aluminum-lined vessels was 462 cycles; the average for the titanium-lined vessels was 2190 cycles.

Hamstad, M. A.↗
NASA NTRS2022

Spacecraft Passivation - An Overview of Requirements, Principles, and Practices as Applied to Spacecraft Pressure Vessels

Explosions, collisions, and other catastrophic breakups of launch vehicle orbital stages and satellites continue to be major contributors to the generation of orbital debris. Both launch vehicles and payload satellites typically have several types of stored energy sources on board, any of which might result in energetic breakups and the creation of debris after their mission has ended. These energy sources include propulsion systems, pressure vessels, reaction wheels, control moment gyros, heat pipes, and power systems. NASA, ESA, JAXA and other space-faring organizations have requirements in place to limit the growth of the orbital debris population by passivating space vehicles that remain in orbit after their missions have ended. In this paper, we review current spacecraft passivation philosophies and principles, as well as how those principles have been applied in practice. In particular, we focus on how NASA programs have addressed spacecraft passivation. We begin by considering and reviewing general passivation requirements, with specific emphasis on pressure vessel passivation. We then discuss passivation approaches used in several recent NASA missions as well as some practical considerations in spacecraft passivation, and conclude by providing some summary guidelines regarding what may be considered acceptable (reduced) pressure level targets (depending on the tank commodity and the type of propulsion system) that could allow the pressure vessel to be considered in a passivated state.

Scott Hull↗
NASA NTRS2021

Astro-biological Exploration of Ocean Worlds, Enabled by an RPS Inside a Pressure Vessel

Exploring Ocean and Ice Worlds could help us to understand the origin and evolution of life in the universe. In our solar system we have identified six Ocean and Ice Worlds, namely Earth, Europa, Ganymede, Callisto, Enceladus, and Titan. Other potential targets include Dione, Triton, and Pluto. As documented in the Planetary Decadal Survey [1] and the NASA Roadmap to Ocean Worlds [2], these worlds are compelling science destinations, with oceans situated below their tens of kilometers thick ice shells. To reach them we need a new exploration paradigm with novel technological solutions. Key technological challenges revolve around the power for the probe and for melting, as well as protecting the payload against the extreme environments, including high pressure, low temperature, corrosion, and radiation. Far away from the Sun, and melted into the ice, we may only rely on long-lived internal power generation. Radioisotope Power Systems (RPS) with either static or dynamic conversion, utilizing the heat of decaying Plutonium-238, could be good candidates. We need suitable payloads that are protected and could survive the extreme environments, as well as enabling power and thermal systems for melting through the ice shield and to swim in the ocean below the ice. RPS could support the probe’s instruments and sub-systems, as well as provide a heat source for melting the ice while keeping the components at operating temperatures. Mitigating the external pressure while immersing inside the ice shell, and in the ocean, would require a new RPS design that operates inside a Pressure Vessel. In our paper, we will discuss general mission architecture trades and the sizing of a next generation RPS housed in a pressure vessel, broadly applicable to any of the Ocean Worlds satellites of interest. Through a technology focused approach, we address interconnected design and mission architecture aspects, including considerations for: the RPS and the Pressure Vessel; extreme environmental constraints; g-load tolerance; power and thermal systems sizing for science measurements; spacecraft operations through all mission phases; subsurface mobility; and planetary protection. The findings will inform the science community on instrument accommodation possibilities; the mission planning community on possible mission concepts; and the RPS development community on the science driven technology considerations.

Donitz, Benjamin P.↗