Search NASA⌕ Search

SEARCH · Search NASA

Results for “MAGNETOSTRICTION”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Universal approach to analysis of cavitation and liquid-impingement erosion data

Cavitation erosion experimental data was analyzed by using normalization and curve-fitting techniques. Data were taken from experiments on several materials tested in both a rotating disk device and a magnetostriction apparatus. Cumulative average volume loss rate and time data were normalized relative to the peak erosion rate and the time to peak erosion rate, respectively. From this process a universal approach was derived that can include data on specific materials from different test devices for liquid impingement and cavitation erosion studies.

Rao, P. V.↗
NASA NTRS1983

A comprehensive analysis of cavitation and liquid impingement erosion data

Cavitation-erosion experimental data previously covering several materials tested in a rotating disk device and a magnetostriction apparatus were analyzed using new normalization and curve-fitting techniques. From this process a universal approach is derived which can include data from cavitation and liquid impingement studies for specific materials from different test devices.

Rao, P. V.↗
NASA NTRS1983

Cavitation Erosion of Copper, Brass, Aluminum and Titanium Alloys in Mineral Oil

The variations of the mean depth of penetration, the mean depth rate of penetration, MDRP, the pit diameter 2a and depth h due to cavitation attack on Al 6061-T6, Cu, brass of composition Cu-35Zn-3Pb and Ti-5A1-2.5Sn are presented. The experiments are conducted in a mineral oil of viscosity 110 CS using a magnetostrictive oscillator of 20 kHz frequency. Based on MDRP on the materials, it is found that Ti-5Al-2.5Sn exhibits cavitation erosion resistance which is two orders of magnitude higher than the other three materials. The values of h/a are the largest for copper and decreased with brass, titanium, and aluminum. Scanning electron microscope studies show that extensive slip and cross slip occurred on the surface prior to pitting and erosion. Twinning is also observed on copper and brass.

Rao, B. C. S.↗
NASA NTRS1984

Empirical relations for cavitation and liquid impingement erosion processes

A unified power-law relationship between average erosion rate and cumulative erosion is presented. Extensive data analyses from venturi, magnetostriction (stationary and oscillating specimens), liquid drop, and jet impact devices appear to conform to this relation. A normalization technique using cavitation and liquid impingement erosion data is also presented to facilitate prediction. Attempts are made to understand the relationship between the coefficients in the power-law relationships and the material properties.

Rao, P. V.↗
NASA NTRS1984

Characterization of erosion of metallic materials under cavitation attack in a mineral oil

Cavitation erosion and erosion rates of eight metallic materials representing three crystal structures were studied using a 20-kHz ultrasonic magnetostrictive oscillator in viscous mineral oil. The erosion rates of the metals with an fcc matrix were 10 to 100 times higher than that of an hcp-matrix titanium alloy. The erosion rates of iron and molybdenum, with bcc matrices, were higher than that of the titanium alloy but lower than those of the fcc metals. Scanning electron microscopy indicates that the cavitation pits are initially formed at the grain boundaries and precipitates and that the pits that formed at the triple points grew faster than the others. Transcrystalline craters formed by cavitation attack over the surface of grains and roughened the surfaces by multiple slip and twinning. Surface roughness measurements show that the pits that formed over the grain boundaries deepended faster than other pits. Computer analysis revealed that a geometric expression describes the nondimensional erosion curves during the time period 0.5 t(0) t 2.5 t(0), where t(0) is the incubation period. The fcc metals had very short incubation periods; the titanium alloy had the longest incubation period.

Rao, B. C. S.↗
NASA NTRS1985

Characterization of erosion of metallic materials under cavitation attack in a mineral oil

Cavitation erosion and erosion rates of eight metallic materials representing three crystal structures were studied. The erosion experiments were conducted with a 20-kHz ultrasonic magnetostrictive oscillator in a viscous mineral oil. The erosion rates of the metals with an fcc matrix were 10 to 100 times higher than that of an hop-matrix titanium alloy. The erosion rates of iron and molybdenum, with bcc matrices, were higher than that of the titanium alloy but lower than those of those of the fcc materials. Studies with scanning electron microscopy indicated that the cavitation pits were initially formed at the grain boundaries and precipitates and that the pits formed at the junction of grain boundaries grew faster than the others. Transcrystalline craters formed by cavitation attack over the surface of grains and roughened the surfaces by multiple slip and twinning. Surface roughness measurements showed that the pits that formed over the grain boundaries deepened faster than pits. Computer analysis revealed that a geometric expression describes the nondimensional erosion curves during the time period 0.5 t (sub 0) t 2.5 t (sub 0), where t (sub 0) is the incubation period. The fcc metals had very short incubation periods; the titanium alloy had the longest incubation period.

Rao, B. C. S.↗
NASA NTRS1984

A unified relation for cavitation erosion

A power-law relationship between the average erosion rate and cumulative erosion is presented. Data analyses from Venturi, magnetostriction, and liquid-impingement devices conform to this unified relation. A normalization technique is also suggested for prediction purposes.

Veerabhadra Rao, P.↗
NASA NTRS1987

Deformation and fracture of single-crystal and sintered polycrystalline silicon carbide produced by cavitation

An investigation was conducted to examine the deformation and fracture behavior of single-crystal and sintered polycrystalline SiC surfaces exposed to cavitation. Cavitation erosion experiments were conducted in distilled water at 25 C by using a magnetostrictive oscillator in close proximity (1 mm) to the surface of SiC. The horn frequency was 20 kHz, and the double amplitude of the vibrating disk was 50 microns. The results of the investigation indicate that the SiC (0001) surface could be deformed in a plastic manner during cavitation. Dislocation etch pits were formed when the surface was chemically etched. The number of defects, including dislocations in the SiC (0001) surface, increased with increasing exposure time to cavitation. The presence of intrinsic defects such as voids in the surficial layers of the sintered polycrystalline SiC determined the zones at which fractured grains and fracture pits (pores) were generated. Single-crystal SiC had superior erosion resistance to that of sintered polycrystalline SiC.

Miyoshi, Kazuhisa↗
NASA NTRS1987

Invar and Elinvar type amorphous Fe-Cr-B alloys with high corrosion resistance

Amorphous (Fe(1-x)Cr(x))85B15 alloys (x = 0 to 0.15) were prepared from the melts by rapid quenching using a single roller techinque, and their Invar and Elinvar characteristics and corrosion resistance were investigated. With an increase in chromium content the Curie temperature and the saturation magnetic moment per iron atom decreased monotonically, while the crystallization temperature incresed gradually. The thermal expansion coefficient alpha around room temperature became slightly larger with increasing chromium content. Nevertheless, these amorphous alloys exhibited excellent Invar characteristics below the Curie temperature. The value of Young's modulus increased remarkably in a relatively low magnetic field and then saturated at a field of about 80 kA/m, showing a large delta E effect. Its value as well as a longitudinal linear magnetostriction became smaller with an increase in chromium content. The temperature coefficient of Young's modulus changed from postive to negative, and the temperature range showing the Elinvar characteristics became narrower with chromium content. The temperature coefficient of delay time determined from the values of alpha and e was very small. The corrosion resistance of these alloys was extremely improved by chromium addition.

Kikuci, M.↗
NASA NTRS1986

Plastic deformation of a magnesium oxide 001-plane surface produced by cavitation

An investigation was conducted to examine plastic deformation of a cleaved single-crystal magnesium oxide 001-plane surface exposed to cavitation. Cavitation damage experiments were carried out in distilled water at 25 C by using a magnetostrictive oscillator in close proximity (2 mm) to the surface of the cleaved specimen. The dislocation-etch-pit patterns induced by cavitation were examined and compared with that of microhardness indentations. The results revealed that dislocation-etch-pit patterns around hardness indentations contain both screw and edge dislocations, while the etch-pit patterns on the surface exposed to cavitation contain only screw dislocations. During cavitation, deformation occurred in a thin surface layer, accompanied by work-hardening of the ceramic. The row of screw dislocations underwent a stable growth, which was analyzed crystallographically.

Hattori, S.↗
NASA NTRS1989

Deformation and fracture of single-crystal and sintered polycrystalline silicon carbide produced by cavitation

An investigation was conducted to examine the deformation and fracture behavior of single-crystal and sintered polycrystalline SiC surfaces exposed to cavitation. Cavitation erosion experiments were conducted in distilled water at 25 C by using a magnetostrictive oscillator in close proximity (1 mm) to the surface of SiC. The horn frequency was 20 kHz, and the double amplitude of the vibrating disk was 50 microns. The results of the investigation indicate that the SiC (0001) surface could be deformed in a plastic manner during cavitation. Dislocation etch pits were formed when the surface was chemically etched. The number of defects, including dislocations in SiC (0001) surface, increased with increasing exposure time to cavitation. The presence of intrinsic defects such as voids in the surficial layers of the sintered polycrystalline SiC determined the zones at which fractured grains and fracture pits (pores) were generated. Single-crystal SiC had superior erosion resistance to that of sintered polycrystalline SiC.

Miyoshi, Kazuhisa↗
NASA NTRS1989

Recent advances in engineering science; Proceedings of the A. Cemal Eringen Symposium, University of California, Berkeley, June 20-22, 1988

Various papers on recent advances in engineering science are presented. Some individual topics addressed include: advances in adaptive methods in computational fluid mechanics, mixtures of two medicomorphic materials, computer tests of rubber elasticity, shear bands in isotropic micropolar elastic materials, nonlinear surface wave and resonator effects in magnetostrictive crystals, simulation of electrically enhanced fibrous filtration, plasticity theory of granular materials, dynamics of viscoelastic media with internal oscillators, postcritical behavior of a cantilever bar, boundary value problems in nonlocal elasticity, stability of flexible structures with random parameters, electromagnetic tornadoes in earth's ionosphere and magnetosphere, helicity fluctuations and the energy cascade in turbulence, mechanics of interfacial zones in bonded materials, propagation of a normal shock in a varying area duct, analytical mechanics of fracture and fatigue.

Koh, Severino L.↗
NASA NTRS1991

Stabilization of large space structures by linear reluctance actuators

Application of magnetic forces are considered for stabilization of vibrations of flexible space structures. Three electromagnetic phenomena are studied, such as: (1) magnetic body force; (2) reluctance torque; and (3) magnetostriction, and their application is analyzed for stabilization of a beam. The magnetic body force actuator uses the force that exists between poles of magnets. The reluctance actuator is configured in such a way that the reluctance of the magnetic circuit will be minimum when the beam is straight. Any bending of the beam increases the reluctance and hence generates a restoring torque that reduces bending. The gain of the actuator is controlled by varying the magnetizing current. Since the energy density of a magnetic device is much higher compared to piezoelectric or thermal actuators, it is expected that the reluctance actuator will be more effective in controlling the structural vibrations.

Biswas, Saroj K.↗
NASA NTRS1991

Effects of ultravacuum and space environment on contact ohmic resistance (AO 138-11)

The experiment was aimed at checking compatibility of the aluminum conductors with conventional conductors and contacts under different conditions of manufacturing (mechanical or magnetostrictive crimping) and storage in laboratory or in long-duration space environment. The electrical characteristics of connections built from nickel-plated conductors and glided copper contacts were noted to vary over the duration of the experiment. These variations are unrelated with the crimping or storage conditions or with metal pairing (nickel-plated aluminum/tinned or silver copper). Such evolutions, even slight, are detrimental to connection quality. The same observations hold for some like connections subjected to long-duration thermal cycles. Therefore, work on aluminum technology was reoriented toward a silver aluminum conductor/ golded aluminum contact solution. The first evaluation test performed according to this definition have yielded satisfactory results.

Assie, Jean Pierre↗
NASA NTRS1992

A state-of-the-art assessment of active structures

A state-of-the-art assessment of active structures with emphasis towards the applications in aeronautics and space is presented. It is felt that since this technology area is growing at such a rapid pace in many different disciplines, it is not feasible to cover all of the current research but only the relevant work as relates to aeronautics and space. Research in smart actuation materials, smart sensors, and control of smart/intelligent structures is covered. In smart actuation materials, piezoelectric, magnetostrictive, shape memory, electrorheological, and electrostrictive materials are covered. For sensory materials, fiber optics, dielectric loss, and piezoelectric sensors are examined. Applications of embedded sensors and smart sensors are discussed.

Source record↗
NASA NTRS1992

Structures that adapt to space

It is shown that by allowing adjustments in space, designs that incorporate adaptive structures can reduce initial precision requirements and lower costs. Present and future spacecraft structures will need enhancements in performance, reliability, testability, and cost-effectiveness; unless a structural system meets these demands, it probably will never be implemented operationally. Attention is given to the ASTREX test facility at Edwards AFB that includes embedded piezoelectric, in-line piezoelectric actuator, and magnetostrictive active members whose testbed rapidly slews the spacecraft through large angles and then points it quickly and accurately.

Wada, Ben K.↗
NASA NTRS1992

Advanced mechanisms for robotics

An overview of applied research and development at NASA-Goddard (GSFC) on mechanisms and the collision avoidance skin for robots is presented. First the work on robot end effectors is outlined, followed by a brief discussion on robot-friendly payload latching mechanisms and compliant joints. This, in turn, is followed by the collision avoidance/management skin and the GSFC research on magnetostrictive direct drive motors. Finally, a new project, the artificial muscle, is introduced. Each of the devices is described in sufficient detail to permit a basic understanding of its purpose, fundamental principles of operation, and capabilities. In addition, the development status of each is reported along with descriptions of breadboards and prototypes and their test results. In each case, the implications of the research for commercialization is discussed. The chronology of the presentation will give a clear idea of both the evolution of the R&D in recent years and its likely direction in the future.

Vranish, John M.↗
NASA NTRS1993

Fiber optic and laser sensors X; Proceedings of the Meeting, Boston, MA, Sept. 8-11, 1992

Topics addressed include acoustic and pressure sensors; fiber optic gyros; electric and magnetic field sensors; bend, strain, and temperature sensors; industrial applications of sensors; and processing techniques. Particular attention is given to fiber optic interferometric acoustic sensors for wind tunnel applications, polished coupler and resonator fabrication, second-harmonic detection for rotation sensing in fiber optic gyros, simplified control theory in closed-loop fiber optic gyroscopes, and a Fabry-Perot sensor with digital signal processing for the measurement of magnetostriction. Also discussed are a Bragg fiber laser sensor, commercialization of fiber optic strain gauge systems, thermal ignition in hazardous environments due to stray light from optical fibers, a system for absolute measurements by interferometric sensors, and high-performance interferometric demodulation techniques.

Udd, Eric↗