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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 1,441 records · Page 80

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NASA NTRS1972

A technique for position sensing and improved momentum evaluation of microparticle impacts in space.

The design of a three element piezoelectric microparticle impact sensing diaphragm is described which is sensitive to the detection of momentum propagated by the bending wave. The design achieves a sensitivity of .03 microdyn/sec and optimizes the detection of the direct-path pulse from impact relative to secondary reflections and interference from discontinuities. Measurement of the relative arrival times and the maximum amplitudes of the outputs from the three piezoelectric sensors leads to the determination of the impact position and the normally resolved impact momentum exchange. Coincidence of the signals and a partial redundancy of data leads to a very high noise discrimination.

Mcdonnell, J. A. M.↗

NASA NTRS1972

An 810 ft/sec soil impact test of a 2-foot diameter model nuclear reactor containment system

A soil impact test was conducted on a 880-pound 2-foot diameter sphere model. The impact area consisted of back filled desert earth and rock. The impact generated a crater 5 feet in diameter by 5 feet deep. It buried itself a total of 15 feet - as measured to the bottom of the model. After impact the containment vessel was pressure checked. No leaks were detected nor cracks observed.

Puthoff, R. L.↗

NASA NTRS1973

Factors affecting miniature Izod impact strength of tungsten-fiber-metal-matrix

The miniature Izod and Charpy impact strengths of copper, copper-nickel, and nickel-base superalloy uniaxially reinforced with continuous tungsten fibers were studied. In most cases, impact strength was increased by increasing fiber or matrix toughness, decreasing fibermatrix reaction, increasing test temperature, hot working, or heat treating. Notch sensitivity was reduced by increasing fiber content or matrix toughness. An equation relating impact strength to fiber and matrix properties and fiber content was developed. Program results imply that tungsten alloy-fiber/superalloy matrix composites can be made with adequate impact resistance for turbine blade or vane applications.

Winsa, E. A.↗

NASA NTRS1973

Reactivity change in a fast-spectrum space power reactor due to a 328-meter-per-second (1075-ft/sec) impact

Application of nuclear reactors in space will present operational problems. One such problem is the possibility of an earth impact at velocities in excess of 305 m/sec (1000 ft/sec). This report shows the results of an impact against concrete at 328 m/sec (1075 ft/sec) and examines the deformed core to estimate the range of activity inserted as a result of the impact. The results of this examination are that the deformation of the reactor core within the containment vessel left only an estimated 2.7 percent void in the core and that the reactivity inserted due to this impact deformation could be from 4.0 to 10.25 dollars.

Peoples, J. A., Jr.↗

NASA NTRS1973

Lunar and terrestrial impact crater spherules.

Comparisons between the chemistry of impact debris, especially spherical droplets of impact-formed material, are made for lunar samples and for soil samples taken from terrestrial impact sites. Differences are assigned to differences in the chemistry of impacting bodies and in the surface rocks, and to the influence of the atmosphere in the terrestrial cases.

Hodge, P. W.↗

NASA NTRS1973

Impact resistance of composite fan blades

The resistance of current-design Pratt and Whitney Aircraft low aspect ratio advanced fiber reinforced epoxy matrix composite fan blades to foreign object damage (FOD) at STOL operating conditions was investigated. Five graphite/epoxy and five boron/epoxy wide chord fan blades with nickel plated stainless steel leading edge sheath protection were fabricated and impact tested. The fan blades were individually tested in a vacuum whirlpit under FOD environments. The FOD environments were typical of those encountered in service operations. The impact objects were ice balls, gravel, stralings and gelatin simulated birds. Results of the damage sustained from each FOD impact are presented for both the graphite boron reinforced blades. Tests showed that the present design composite fan blades, with wrap around leading edge protection have inadequate FOD impact resistance at 244 m/sec (800 ft/sec) tip speed, a possible STOL operating condition.

Premont, E. J.↗

NASA NTRS1973

Application of the Collision-Imparted Velocity Method for Analyzing the Responses of Containment and Deflector Structures to Engine Rotor Fragment Impact

An approximate analysis, termed the Collision Imparted Velocity Method (CIVM), was employed for predicting the transient structural responses of containment rings or deflector rings which are subjected to impact from turbojet-engine rotor burst fragments. These 2-d structural rings may be initially circular or arbitrarily curved and may have either uniform or variable thickness; elastic, strain hardening, and strain rate material properties are accommodated. This approximate analysis utilizes kinetic energy and momentum conservation relations in order to predict the after-impact velocities of the fragment and the impacted ring segment. This information is then used in conjunction with a finite element structural response computation code to predict the transient, large deflection responses of the ring. Similarly, the equations of motion for each fragment are solved in small steps in time. Also, some comparisons of predictions with experimental data for fragment-impacted free containment rings are presented.

Collins, T. P.↗

NASA NTRS1973

Water impact studies

An investigation has begun into the potential impact of using modern remote sensing techniques as an aid in managing, even on a day-to-day basis, the storage, flow, and delivery of water made available through the California Water Project. It is obvious that the amount of this impact depends upon the extent to which remote sensing is proven to be useful in improving predictions of both the amount of water that will be available and the amount that will be needed. It is also proposed to investigate the potential impact of remote sensing techniques as an aid in monitoring, and perhaps even in directing, changes in land use and life style being brought about through the increased availability of water in central and southern California as a result of the California Water Project. The impact of remote sensing can be of appreciable significance only if: (1) the induced changes are very substantial ones; (2) remote sensing is found, in this context, to be very useful and potentially very cost effective; and (3) resource managers adopt this new technology. Analyses will be conducted of the changing economic bases and the new land use demands resulting from increased water availability in central and southern California.

Colwell, R. N.↗

NASA NTRS1973

Impact resistance of current design composite fan blades tested under short-haul operating conditions

Boron/epoxy and graphite/epoxy composite blades were impacted in a rotating whirligig facility with conditions closely simulating those which might be experienced by a STOL engine impacted with various foreign objects. The tip speed of the rotating blades was 800 feet per second. The blades were impacted with simulated birds, real birds, ice balls, and gravel. The results of composite blade impact tests were compared with a titanium blade tested under similar conditions. Neither composite material indicated a clear superiority over the other. Blades made from both composite materials showed more damage than the titanium blades.

Steinhagen, C. A.↗

NASA NTRS1973

Conical scan impact study. Volume 1: General central data processing facility

The impact of a conical scan versus a linear scan multispectral scanner (MSS) instrument was studied in terms of: (1) design modifications required in framing and continuous image recording devices; and (2) changes in configurations of an all-digital precision image processor. A baseline system was defined to provide the framework for comparison, and included pertinent spacecraft parameters, a conical MSS, a linear MSS, an image recording system, and an all-digital precision processor. Lateral offset pointing of the sensors over a range of plus or minus 20 deg was considered. The study addressed the conical scan impact on geometric, radiometric, and aperture correction of MSS data in terms of hardware and software considerations, system complexity, quality of corrections, throughput, and cost of implementation. It was concluded that: (1) if the MSS data are to be only film recorded, then there is only a nomial concial scan impact on the ground data processing system; and (2) if digital data are to be provided to users on computer compatible tapes in rectilinear format, then there is a significant conical scan impact on the ground data processing system.

Ebert, D. H.↗

NASA NTRS1973

Igneous vs impact processes for the origin of the Mare lavas

The respective role of external vs internal processes is considered. The inner Orientale basin was formed by the explosive impact of an asteroidal body. Within minutes after the impact, the concentric fracture system developed as an adjustment to the stresses generated by the shock wave. Examples are presented to illustrate that the upwelling of lava in the center of Mare Orientale and several craters on its ejecta blanket occurred well after the asteroidal collision which generated the bulls-eye structure. Thus, the lavas were not strictly impact melts. However, a close relationship may have existed between the impact and subsequent volcanism.

Gornitz, V.↗

NASA NTRS1974

Impact resistance of composite fan blades

Results are presented of a program to determine the impact resistance of composite fan blades subjected to foreign object damage (FOD) while operating under conditions simulating a short take-off and landing (STOL) engine at takeoff. The full-scale TF39 first-stage fan blade was chosen as the base design for the demonstration component since its configuration and operating tip speeds are similar to a typical STOL fan blade several composite configurations had already been designed and evaluated under previous programs. The first portion of the program was devoted toward fabricating and testing high impact resistant, aerodynamically acceptable composite blades which utilized only a single material system in any given blade. In order to increase the blade impact capability beyond this point, several mixed material (hybrid) designs were investigated using S-glass and Kevlar as well as boron and graphite fibers. These hybrid composite blades showed a marked improvement in resistance to bird impact over those blades made of a single composite material. The work conducted under this program has demonstrated substantial improvement in composite fan blades with respect to FOD resistance and has indicated that the hybrid design concept, which utilizes different types of fibers in various portions of a fan blade design depending on the particular requirements of the different areas and the characteristics of the different fibers involved, shows a significant improvement over those designs utilizing only one material system.

Source record↗

NASA NTRS1974

Analysis of edge impact stresses in composite plates

The in-plane edge impact of composite plates, with or without a protection strip, is investigated. A computational analysis based on the Fast Fourier Transform technique is presented. The particular application of the present method is in the understanding of the foreign object damage problem of composite fan blades. The method is completely general and may be applied to the study of other stress wave propagation problems in a half space. Results indicate that for the protective strip to be effective in reducing impact stresses in the composite the thickness must be equal or greater than the impact contact dimension. Large interface shear stresses at the strip - composite boundary can be induced under impact.

Moon, F. C.↗

NASA NTRS1974

Glass production differences for equal-diameter impact craters

A thermodynamic model of meteorite impact is used to investigate the possibility that the creation of two impact craters of the same apparent diameter may have been accompanied by dissimilar shock heating regimes. For small craters, the idea may be concisely represented by the question of which event produces more glass, a large slow meteorite or a small fast one, if the resulting craters are of the same diameter. So that the results may be most apparent, the only parameters varied in this study are meteorite size and impact velocity. Identical basaltic material is assumed for meteorite and target. For impact velocities between 10 and 70 km/sec, an available model determines the radius of a spherical meteorite which would produce a crater diameter of 20 cm.

Rehfuss, D. E.↗

NASA NTRS1975

Impact response of graphite-epoxy flat laminates using projectiles that simulate aircraft engine encounters

An investigation of the response of a graphite-epoxy material to foreign object impact was made by impacting spherical projectiles of gelatin, ice, and steel normally on flat panels. The observed damage was classified as transverse (stress wave delamination and cracking), penetrative, or structural (gross failure): the minimum, or threshold, velocity to cause each class of damage was established as a function of projectile characteristics. Steel projectiles had the lowest transverse damage threshold, followed by gelatin and ice. Making use of the threshold velocities and assuming that the normal component of velocity produces the damage in nonnormal impacts, a set of impact angles and velocities was established for each projectile material which would result in damage to composite fan blades. Analysis of the operating parameters of a typical turbine fan blade shows that small steel projectiles are most likely to cause delamination and penetration damage to unprotected graphite-epoxy composite fan blades.

Preston, J. L., Jr.↗

NASA NTRS1975

Impact fracture of composite sandwich structures

An experimental investigation of impact-initiated failures in high-strength graphite/epoxy and Kevlar-49/epoxy sandwich structures has been conducted. The tests consisted of firing small diameter aluminum projectiles with a velocity range of 16-67 meters/second (52-220 ft/sec) at preloaded sandwich specimens. These tests were intended to be representative of service conditions on materials and structures which might be used as secondary aircraft components. The preload and impact energy necessary to initiate catastrophic failure were determined. The residual strength of impact-damaged specimens was also measured. The results of these tests indicate that catastrophic failures in sandwich structures can be initiated at relatively low preloads by impact projectiles at energy levels well below that required to initiate visible damage.

Rhodes, M. D.↗

NASA NTRS1975

Rocks 60618 and 65785 - Evidence for admixture of KREEP in lunar impact melts

We present evidence to support the hypothesis that the fine-grained, basaltic-textured portions of rocks 60618 and 65785 were produced by impact melting of the coarse-grained spinel-olivine anorthosite (60618) and spinel troctolite (65785) portions, coupled with admixture of approximately 33% and 63%, respectively, material of alkalic high-alumina basalt (KREEP) composition. The abundance of impact-modified rocks at the Apollo 16 site with compositional similarities to the impact melts reported here, suggests that the relations observed in these rocks are indicative of widespread impact mixing with KREEP in rocks of the lunar highlands.

Keil, K.↗

NASA NTRS1976

The economic impact of NASA R and D spending: Executive summary

An evaluation of the economic impact of NASA research and development programs is made. The methodology and the results revolve around the interrelationships existing between the demand and supply effects of increased research and development spending, in particular, NASA research and development spending. The INFORUM Inter-Industry Forecasing Model is used to measure the short-run economic impact of alternative levels of NASA expenditures for 1975. An aggregate production function approach is used to develop the data series necessary to measure the impact of NASA research and development spending, and other determinants of technological progress, on the rate of growth in productivity of the U. S. economy. The measured relationship between NASA research and development spending and technological progress is simulated in the Chase Macroeconometric Model to measure the immediate, intermediate, and long-run economic impact of increased NASA research and development spending over a sustained period.

Evans, M. K.↗