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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2016

Non-Axisymmetric Inflatable Pressure Structure (NAIPS) Concept that Enables Mass Efficient Packageable Pressure Vessels with Sealable Openings

Achieving minimal launch volume and mass are always important for space missions, especially for deep space manned missions where the costs required to transport mass to the destination are high and volume in the payload shroud is limited. Pressure vessels are used for many purposes in space missions including habitats, airlocks, and tank farms for fuel or processed resources. A lucrative approach to minimize launch volume is to construct the pressure vessels from soft goods so that they can be compactly packaged for launch and then inflated en route or at the final destination. In addition, there is the potential to reduce system mass because the packaged pressure vessels are inherently robust to launch loads and do not need to be modified from their in-service configuration to survive the launch environment. A novel concept is presented herein, in which sealable openings or hatches into the pressure vessels can also be fabricated from soft goods. To accomplish this, the structural shape is designed to have large regions where one principal stress is near zero. The pressure vessel is also required to have an elongated geometry for applications such as airlocks.

Doggett, William R.↗
NASA NTRS1974

Polymer-lined filament-wound pressure vessels for nitrogen containment

A program has been started to develop fatigue-resistant polymeric liners for a filament-wound pressure vessel to contain nitrogen gas at room temperature. First, nitrogen permeation of butyl rubber sheet coated with Saran and Parylene C was studied in flat specimens. Then four 10-cm-diam cylindrical pressure vessels were prepared with chlorobutyl rubber liners coated with the same materials. These vessels were valved off after nitrogen gas pressurization to approximately 65% (approximately 11.7 MPa or 1700 psig) of their expected failure pressure. One vessel leaked. The other three vessels showed an average pressure loss of less than 1% per month. These pressure vessels have an average performance factor of approximately 370 kPa-cu m/kg (1,500,000 in.) based on composite mass.

Hamstad, M. A.↗
NASA NTRS1974

Polymer-lined filament-wound pressure vessels for nitrogen containment

A program has been started to develop fatigue-resistant polymeric liners for a filament-wound pressure vessel to contain nitrogen gas at room temperature. First, nitrogen permeation of butyl rubber sheet coated with Saran and Parylene C was studied in flat specimens. Then four 10-cm-diam cylindrical pressure vessels were prepared with chlorobutyl rubber liners coated with the same materials. These vessels were valved off after nitrogen gas pressurization to approximately 65% of their expected failure pressure. One vessel leaked. The other three vessels showed an average pressure loss of less than 1% per month. These pressure vessels have an average performance factor of about 370 kPa x cu m/kg based on composite mass.

Hamstad, M. A.↗
NASA NTRS1993

J-integral patch for finite element analysis of dynamic fracture due to impact of pressure vessels

Prediction of whether a pressurized cylinder will fail catastrophically when impacted by a projectile has important applications ranging from perforation of an airplane's skin by a failed turbine blade to meteorite impact of a space station habitation module. This report summarizes the accomplishment of one task for a project whose aim is to simulate numerically the outcome of a high velocity impact of pressure vessels. A finite element patch covering the vicinity of a growing crack has been constructed to estimate the J-integral (crack driving force) during the impact. Explicit expressions for the J-integral through the nodal values of displacement, strain, and stress have been written. The patch is to be used repeatedly to estimate the amount of crack growth during the time of the impact. The resulting crack size is to be compared to an estimated critical crack size for the pressurized cylinder.

Kunin, Boris I.↗
NASA NTRS1977

Recent advances in lightweight, filament-wound composite pressure vessel technology

A review of recent advances is presented for lightweight, high-performance composite pressure vessel technology that covers the areas of design concepts, fabrication procedures, applications, and performance of vessels subjected to single-cycle burst and cyclic fatigue loading. Filament-wound fiber/epoxy composite vessels were made from S-glass, graphite, and Kevlar 49 fibers and were equipped with both structural and nonstructural liners. Pressure vessel structural efficiencies were attained which represented weight savings, using different liners, of 40 to 60 percent over all-titanium pressure vessels. Significant findings in each area are summarized including data from current NASA-Lewis Research Center contractual and in-house programs.

Lark, R. F.↗
NASA NTRS1973

Improved fireman's compressed air breathing system pressure vessel development program

Prototype high pressure glass filament-wound, aluminum-lined pressurant vessels suitable for use in a fireman's compressed air breathing system were designed, fabricated, and acceptance tested in order to demonstrate the feasibility of producing such high performance, lightweight units. The 4000 psi tanks have a 60 standard cubic foot (SCF) air capacity, and have a 6.5 inch diamter, 19 inch length, 415 inch volume, weigh 13 pounds when empty, and contain 33 percent more air than the current 45 SCF (2250 psi) steel units. The current steel 60 SCF (3000 psi) tanks weigh approximately twice as much as the prototype when empty, and are 2 inches, or 10 percent shorter. The prototype units also have non-rusting aluminum interiors, which removes the hazard of corrosion, the need for internal coatings, and the possibility of rust particles clogging the breathing system.

King, H. A.↗
NASA NTRS2017

Some Observations on Damage Tolerance Analyses in Pressure Vessels

AIAA standards S080 and S081 are applicable for certification of metallic pressure vessels (PV) and composite overwrap pressure vessels (COPV), respectively. These standards require damage tolerance analyses with a minimum reliable detectible flaw/crack and demonstration of safe life four times the service life with these cracks at the worst-case location in the PVs and oriented perpendicular to the maximum principal tensile stress. The standards require consideration of semi-elliptical surface cracks in the range of aspect ratios (crack depth a to half of the surface length c, i.e., (a/c) of 0.2 to 1). NASA-STD-5009 provides the minimum reliably detectible standard crack sizes (90/95 probability of detection (POD) for several non-destructive evaluation (NDE) methods (eddy current (ET), penetrant (PT), radiography (RT) and ultrasonic (UT)) for the two limits of the aspect ratio range required by the AIAA standards. This paper tries to answer the questions: can the safe life analysis consider only the life for the crack sizes at the two required limits, or endpoints, of the (a/c) range for the NDE method used or does the analysis need to consider values within that range? What would be an appropriate method to interpolate 90/95 POD crack sizes at intermediate (a/c) values? Several procedures to develop combinations of a and c within the specified range are explored. A simple linear relationship between a and c is chosen to compare the effects of seven different approaches to determine combinations of aj and cj that are between the (a/c) endpoints. Two of the seven are selected for evaluation: Approach I, the simple linear relationship, and a more conservative option, Approach III. For each of these two Approaches, the lives are computed for initial semi-elliptic crack configurations in a plate subjected to remote tensile fatigue loading with an R-ratio of 0.1, for an assumed material evaluated using NASGRO (registered 4) version 8.1. These calculations demonstrate that for this loading, using Approach I and the initial detectable crack sizes at the (a/c) endpoints in 5009 specified for the ET and UT NDE methods, the smallest life is not at the two required limits of the (a/c) range, but rather is at an intermediate configuration in the range (a/c) of 0.4 to 0.6. Similar analyses using both Approach I and III with the initial detectable crack size at the (a/c) endpoints in 5009 for PT NDE showed the smallest life may be at an (a/c) endpoint or an intermediate (a/c), depending upon which Approach is used. As such, analyses that interrogate only the two (a/c) values of 0.2 and 1 may result in unconservative life predictions. The standard practice may need to be revised based on these results.

Raju, Ivatury S.↗
NASA NTRS2015

Multipurpose Pressure Vessel Scanner and Photon Doppler Velocimetry

Critical flight hardware typically undergoes a series of nondestructive evaluation methods to screen for defects before it is integrated into the flight system. Conventionally, pressure vessels have been inspected for flaws using a technique known as fluorescent dye penetrant, which is biased to inspector interpretation. An alternate method known as eddy current is automated and can detect small cracks better than dye penetrant. A new multipurpose pressure vessel scanner has been developed to perform internal and external eddy current scanning, laser profilometry, and thickness mapping on pressure vessels. Before this system can be implemented throughout industry, a probability of detection (POD) study needs to be performed to validate the system's eddy current crack/flaw capabilities. The POD sample set will consist of 6 flight-like metal pressure vessel liners with defects of known size. Preparation for the POD includes sample set fabrication, system operation, procedure development, and eddy current settings optimization. For this, collaborating with subject matter experts was required. This technical paper details the preparation activities leading up to the POD study currently scheduled for winter 2015/2016. Once validated, this system will be a proven innovation for increasing the safety and reliability of necessary flight hardware. Additionally, testing of frangible joint requires Photon Doppler Velocimetry (PDV) and Digital Image Correlation instrumentation. There is often noise associated with PDV data, which necessitates a frequency modulation (FM) signal-to-noise pre-test. Generally, FM radio works by varying the carrier frequency and mixing it with a fixed frequency source, creating a beat frequency which is represented by audio frequency that can be heard between about 20 to 20,000 Hz. Similarly, PDV reflects a shifted frequency (a phenomenon known as the Doppler Effect) from a moving source and mixes it with a fixed source frequency, which results in a beat frequency. However, for PDV, discerning the signal from the noise is difficult without a moving source to induce the modulation. A rotating wheel is currently being used as the moving source but its configuration is impractical and has cumbersome placement inside the current frangible joint test cell. As a way to combat this problem and verify a satisfactory signal-to-noise ratio, a reflective moving crystal piezo will be used to modulate a beat frequency, and an absorptive target will be used to block the signal in order to determine any back reflection coming from the probe and discern the true signal-to-noise ratio. The piezo will be mounted and inserted onto the test table on an extendable telescopic antenna grounded by a magnetic base in the test zone. This piezo configuration will be more compatible within the test zone and allow for easy removal of the disk following acceptable signal verification and prior to frangible joint tests.

Ellis, Tayera↗
NASA NTRS2015

Multipurpose Pressure Vessel Scanner and Photon Doppler Velocimetry

Critical flight hardware typically undergoes a series of nondestructive evaluation methods to screen for defects before it is integrated into the flight system. Conventionally, pressure vessels have been inspected for flaws using a technique known as fluorescent dye penetrant, which is biased to inspector interpretation. An alternate method known as eddy current is automated and can detect small cracks better than dye penetrant. A new multipurpose pressure vessel scanner has been developed to perform internal and external eddy current scanning, laser profilometry, and thickness mapping on pressure vessels. Before this system can be implemented throughout industry, a probability of detection (POD) study needs to be performed to validate the system’s eddy current crack/flaw capabilities. The POD sample set will consist of 6 flight-like metal pressure vessel liners with defects of known size. Preparation for the POD includes sample set fabrication, system operation, procedure development, and eddy current settings optimization. For this, collaborating with subject matter experts was required. This technical paper details the preparation activities leading up to the POD study currently scheduled for winter 2015/2016. Once validated, this system will be a proven innovation for increasing the safety and reliability of necessary flight hardware.Additionally, testing of frangible joint requires Photon Doppler Velocimetry (PDV) and Digital Image Correlation instrumentation. There is often noise associated with PDV data, which necessitates a frequency modulation (FM) signal-to-noise pre-test. Generally, FM radio works by varying the carrier frequency and mixing it with a fixed frequency source, creating a beat frequency which is represented by audio frequency that can be heard between about 20 to 20,000 Hz. Similarly, PDV reflects a shifted frequency (a phenomenon known as the Doppler Effect) from a moving source and mixes it with a fixed source frequency, which results in a beat frequency. However, for PDV, discerning the signal from the noise is difficult without a moving source to induce the modulation. A rotating wheel is currently being used as the moving source but its configuration is impractical and has cumbersome placement inside the current frangible joint test cell. As a way to combat this problem and verify a satisfactory signal-to-noise ratio, a reflective moving crystal piezo will be used to modulate a beat frequency, and an absorptive target will be used to block the signal in order to determine any back reflection coming from the probe and discern the true signal-to noise ratio. The piezo will be mounted and inserted onto the test table on an extendable telescopic antenna grounded by a magnetic base in the test zone. This piezo configuration will be more compatible within the test zone and allow for easy removal of the disk following acceptable signal verification and prior to frangible joint tests.Additionally, topics of what was learned and smaller tasks given at White Sands Test Facility (WSTF) will be discussed. All statements in this paper are newly gained knowledge of what I have learned, observed, and have done while at WSTF.

Ellis, Tayera↗
NASA NTRS1999

Quantification of Processing Effects on Filament Wound Pressure Vessels

A computational simulation procedure is described which is designed specifically for the modeling and analysis of filament wound pressure vessels. Cylindrical vessels with spherical or elliptical end caps can be generated automatically. End caps other than spherical or elliptical may be modeled by varying circular sections along the x-axis according to the C C! end cap shape. The finite element model generated is composed of plate type quadrilateral shell elements on the entire vessel surface. This computational procedure can also be sued to generate grid, connectivity and material cards (bulk data) for component parts of a larger model. These bulk data are assigned to a user designated file for finite element structural/stress analysis of composite pressure vessels. The procedure accommodates filament would pressure vessels of all types of shells-of-revolution. It has provisions to readily evaluate initial stresses due to pretension in the winding filaments and residual stresses due to cure temperature.

Aiello, Robert A.↗
NASA NTRS2002

Quantification of Processing Effects on Filament Wound Pressure Vessels

A computational simulation procedure is described which is designed specifically for the modeling and analysis of filament wound pressure vessels. Cylindrical vessels with spherical or elliptical end caps can be generated automatically. End caps other than spherical or elliptical may be modeled by varying circular sections along the x-axis according to the end cap shape. The finite element model generated is composed of plate type quadrilateral shell elements on the entire vessel surface. This computational procedure can also be used to generate grid, connectivity and material cards (bulk data) for component parts of a larger model. These bulk data are assigned to a user designated file for finite element structural/stress analysis of composite pressure vessels. The procedure accommodates filament wound pressure vessels of all types of shells-of -revolution. It has provisions to readily evaluate initial stresses due to pretension in the winding filaments and residual stresses due to cure temperature.

Aiello, Robert A.↗
NASA NTRS1977

High-pressure cryogenic seals for pressure vessels

This investigation of the problems associated with reliably containing gaseous helium pressurized to 1530 bars (22 500 psi) between 4.2 K and 150 K led to the following conclusions: (1) common seal designs used in existing elevated-temperature pressure vessels are unsuitable for high-pressure cryogenic operation, (2) extrusion seal-ring materials such as Teflon, tin, and lead are not good seal materials for cryogenic high-pressure operation; and (3) several high-pressure cryogenic seal systems suitable for large-pressure vessel applications were developed; two seals required prepressurization, and one seal functioned repeatedly without any prepressurization. These designs used indium seal rings, brass or 304 stainless-steel anvil rings, and two O-rings of silicone rubber or Kel-F.

Buggele, A. E.↗
NASA NTRS1990

Offset Joint For Segmented Pressure Vessel

Concept for increasing reliability of segmented pressure vessel proposed. Inward offset of tang and clevis bands of encircling joint between segments reduces or eliminates gap opening between tang and inner leg of clevis in response to pressure in vessel.

Moore, Carleton J.↗