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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Mechanical energy output of the 5 September 1973 flare

The mechanical energy flux of observed macroscopic mass plasma motions in the solar flare of Sept. 5, 1973, is estimated. Consideration is given to the cool eruptive material in the eruptive filament and large surge as revealed by H alpha observations, the moving emission front seen in Ca II as well as H alpha, the piston-driven shock and mass ejection coronal transient observed in radio spectra and flare core motions, and mechanical energy estimates of 5.6 x 10 to the 29th to 8.9 x 10 to the 30th, 9.0 x 10 to the 29th, 2 x 10 to the 30th (thermal) and 10 to the 31st (magnetic), and 9 x 10 to the 24th erg are obtained, respectively, in agreement with previous estimates. It is concluded that the mechanical energy of large-scale mass motions dominates the radiative output of the flare by more than two orders of magnitude, and that a significant portion of the mechanical energy is in the form of magnetic flux delivered to interplanetary space.

Webb, D. F.↗
NASA NTRS1999

A mechanical energy analysis of gait initiation

The analysis of gait initiation (the transient state between standing and walking) is an important diagnostic tool to study pathologic gait and to evaluate prosthetic devices. While past studies have quantified mechanical energy of the body during steady-state gait, to date no one has computed the mechanical energy of the body during gait initiation. In this study, gait initiation in seven normal male subjects was studied using a mechanical energy analysis to compute total body energy. The data showed three separate states: quiet standing, gait initiation, and steady-state gait. During gait initiation, the trends in the energy data for the individual segments were similar to those seen during steady-state gait (and in Winter DA, Quanbury AO, Reimer GD. Analysis of instantaneous energy of normal gait. J Biochem 1976;9:253-257), but diminished in amplitude. However, these amplitudes increased to those seen in steady-state during the gait initiation event (GIE), with the greatest increase occurring in the second step due to the push-off of the foundation leg. The baseline level of mechanical energy was due to the potential energy of the individual segments, while the cyclic nature of the data was indicative of the kinetic energy of the particular leg in swing phase during that step. The data presented showed differences in energy trends during gait initiation from those of steady state, thereby demonstrating the importance of this event in the study of locomotion.

Leg/physiology↗
NASA NTRS1977

Mechanical energy storage device for hip disarticulation

An artificial leg including a trunk socket, a thigh section hingedly coupled to the trunk socket, a leg section hingedly coupled to the thigh section and a foot section hingedly coupled to the leg section is outlined. A mechanical energy storage device is operatively associated with the artificial leg for storage and release of energy during the normal walking stride of the user. Energy is stored in the mechanical energy storage device during a weight-bearing phase of the walking stride when the user's weight is on the artificial leg. Energy is released during a phase of the normal walking stride, when the user's weight is removed from the artificial leg. The stored energy is released from the energy storage device to pivot the thigh section forwardly about the hinged coupling to the trunk socket.

Vallotton, W. C.↗
NASA NTRS1992

Mechanical energy flow models of rods and beams

It has been proposed that the flow of mechanical energy through a structural/acoustic system may be modeled in a manner similar to that of flow of thermal energy/in a heat conduction problem. If this hypothesis is true, it would result in relatively efficient numerical models of structure-borne energy in large built-up structures. Fewer parameters are required to approximate the energy solution than are required to model the characteristic wave behavior of structural vibration by using traditional displacement formulations. The energy flow hypothesis is tested in this investigation for both longitudinal vibration in rods and transverse flexural vibrations of beams. The rod is shown to behave approximately according to the thermal energy flow analogy. However, the beam solutions behave significantly differently than predicted by the thermal analogy unless locally-space-averaged energy and power are considered. Several techniques for coupling dissimilar rods and beams are also discussed. Illustrations of the solution accuracy of the methods are included.

Wohlever, J. C.↗
NASA NTRS1992

Temperature rise due to mechanical energy dissipation in undirectional thermoplastic composites(AS4/PEEK)

The history of temperature rise due to internal dissipation of mechanical energy in insulated off-axis uniaxial specimens of the unidirectional thermoplastic composite (AS4/PEEK) has been measured. The experiment reveals that the rate of temperature rise is a polynomial function of stress amplitude: It consists of a quadratic term and a sixth power term. This fact implies that the specific heat of the composite depends on the stretching its microstructure undergoes during deformation. The Einstein theory for specific heat is used to explain the dependence of the specific heat on the stretching of the microstructure.

Georgious, I. T.↗
NASA NTRS1980

Mechanical energy transport

The properties, generation, and dissipation mechanisms of acoustic, gravity and Alfven waves are described, whose restoring forces are pressure, buoyancy, and magnetic tension, respectively. For acoustic waves, generation by turbulent convective motions and by the Eddington Valve thermal overstability is discussed, considering the 'five-minute' oscillation; dissipation is possible either by radiation or shocks. Generation of gravity waves by penetrative convective motions and by shear arising from supergranule motions is reviewed, and dissipation due to wave breaking, interaction with the mean horizontal fluid flow, and very severe radiative damping is considered. Attention is given to Alfven wave generation by convective motions and thermal overstability, and to dissipation by mode coupling, wave decay, current dissipation, and particle collisions producing Joule or viscous heating.

Stein, R. F.↗
NASA NTRS1979

Penrose photoproduction processes - A high efficiency energy mechanism for active galactic nuclei and quasars

Recent observations of NGC 4151 and 3C273 suggest that the nuclei of active galaxies have very high gamma ray efficiencies. In addition, optical studies of M87 have indicated the possibility of a massive black hole in its central region. The above facts have led to study of a new physical mechanism, Penrose Photoproduction Processes, in the ergospheres of massive Kerr black holes, as a way to account for the fluctuating, high efficiency, energy production associated with active galaxies and quasars. Observational signatures, associated with this mechanism, occur in the form of approximately 2 MeV and approximately 2 GeV gamma ray cutoffs which might be corroborated by the observed spectra of NGC 4151 and 3C273, respectively.

Leiter, D.↗
NASA NTRS1993

Mechanical energy absorber

An energy absorbing system for controlling the force where a moving object engages a stationary stop and where the system utilized telescopic tubular members, energy absorbing diaphragm elements, force regulating disc springs, and a return spring to return the telescoping member to its start position after stroking is presented. The energy absorbing system has frusto-conical diaphragm elements frictionally engaging the shaft and are opposed by a force regulating set of disc springs. In principle, this force feedback mechanism serves to keep the stroking load at a reasonable level even if the friction coefficient increases greatly. This force feedback device also serves to desensitize the singular and combined effects of manufacturing tolerances, sliding surface wear, temperature changes, dynamic effects, and lubricity.

Wesselski, Clarence J.↗
NASA NTRS2015

Compliant Electrode and Composite Material for Piezoelectric Wind and Mechanical Energy Conversions

A thin film device for harvesting energy from wind. The thin film device includes one or more layers of a compliant piezoelectric material formed from a composite of a polymer and an inorganic material, such as a ceramic. Electrodes are disposed on a first side and a second side of the piezoelectric material. The electrodes are formed from a compliant material, such as carbon nanotubes or graphene. The thin film device exhibits improved resistance to structural fatigue upon application of large strains and repeated cyclic loadings.

Chen, Bin↗
NASA NTRS2005

Bringing Thunder and Lightning Indoors

Piezoelectric materials convert mechanical energy into electrical energy and electrical energy into mechanical energy. They generate electrical charges in response to mechanical stress and generate mechanical displacement and/or force when subjected to an electric current. Scientists at Langley Research Center have developed a piezoelectric device that is superior in many ways to those that used to be the only ones commercially available. It is tougher, has far greater displacement and greater mechanical load capacity for a comparative voltage operation, can be easily produced at a relatively low cost, and lends itself well to mass production. The NASA-developed piezoelectric device is also unique in that it is more efficient in extracting electrical energy from the mechanical energy that goes in. It works on a simple principle. A thin ceramic piezoelectric wafer is sandwiched between an aluminum sheet and a steel sheet and held together with LaRC-SI, an amorphous thermoplastic adhesive with special properties created by NASA at Langley. The sandwich is heated in an autoclave, and the adhesive melts. When the sandwich cools, the adhesive bonds the parts together into one piezoelectric element. While they cool, the components of the element contract at different rates, since they are made of different materials. This differential shrinkage causes the element to warp in either a convex or concave shape, depending on which way it is oriented. The shrinking of the outside metal layers places the inside piezoelectric ceramic under mechanical stress. If the element is cantilevered by clamping one side and then plucked, it reverberates like a diving board that has just ejected a diver. This way, a small amount of mechanical energy can result in a relatively long period of electrical generation. When the piezoelectric element is used for the creation of electricity, it is called Lightning. This same sandwiched piezoelectric wafer can also convert electrical energy into mechanical energy. Then, it is called Thunder. Electricity goes in, excites the element, and then, mechanical energy in the form of movement is generated.

Source record↗
NASA NTRS1993

Specification list and function structure for a full-body dynamometer to be used aboard Space Station Freedom

NASA has a need for a machine which can be used as an exercise device and as an instrument to measure an astronaut's muscle performance. The purpose of the exercise device is to work various muscle groups of the astronaut to prevent muscle atrophy, the loss of muscle strength and mass from prolonged exposure to a microgravity environment. The measurement part of the machine will be used to collect data on the strength and power of the astronaut's muscle groups to be used in studies examining the effects of prolonged space inhabitation. The principle device used in this machine to both exercise and measure muscle performance is the dynamometer. The dynamometer converts electrical energy to mechanical energy and mechanical energy to electrical energy or signals. The task of the designer will be to incorporate a dynamometer into a device which can meet all of the needs discussed above. This memorandum has two sections which clarify the design task of producing a full-body dynamometer. The first section is a specification list. The specification list provides the requirements that the designer must meet in his/her design. The second part is a function structure. The function structure shows graphically the flow of material, energy, and information through the machine. These two items will be used by the designer in the design process for the full-body dynamometer.

Mcmahan, Robert↗
NASA NTRS1983

Impact resistance of fiber composites: Energy absorbing mechanisms and environmental effects

Energy absorbing mechanisms were identified by several approaches. The energy absorbing mechanisms considered are those in unidirectional composite beams subjected to impact. The approaches used include: mechanic models, statistical models, transient finite element analysis, and simple beam theory. Predicted results are correlated with experimental data from Charpy impact tests. The environmental effects on impact resistance are evaluated. Working definitions for energy absorbing and energy releasing mechanisms are proposed and a dynamic fracture progression is outlined. Possible generalizations to angle-plied laminates are described.

Chamis, C. C.↗
NASA NTRS1985

Impact resistance of fiber composites - Energy-absorbing mechanisms and environmental effects

Energy absorbing mechanisms were identified by several approaches. The energy absorbing mechanisms considered are those in unidirectional composite beams subjected to impact. The approaches used include: mechanic models, statistical models, transient finite element analysis, and simple beam theory. Predicted results are correlated with experimental data from Charpy impact tests. The environmental effects on impact resistance are evaluated. Working definitions for energy absorbing and energy releasing mechanisms are proposed and a dynamic fracture progression is outlined. Possible generalizations to angle-plied laminates are described.

Chamis, C. C.↗
NASA NTRS1982

Study of laser heated propulsion devices. Part 1: Evaluation of laser devices, fuels and energy coupling mechanisms

Closed cycle, CW waveform and short wavelength laser devices are desirable characteristics for laser propulsion. The choice of specific wavelengths for hydrogen fuel affects the operational conditions under which a laser supported absorption (LSA) wave is initiated and maintained. The mechanisms of initiating and maintaining LSA waves depend on the wavelength of the laser. Consequently, the shape and size of the hot core plasma is also dependent on wavelength and pressure. Detailed modeling of these mechanisms must be performed before their actual significance can be ascertained. Inverse bremsstrahlung absorption mechanism is the dominant mechanism for coupling energy into the plasma, but other mechanisms which are wavelength dependent can dictate the LSA wave plasma initiation and maintenance conditions. Multiphoton mechanisms become important at visible or shorter wavelengths. These are important mechanisms in creating the initial H2 gas breakdown and supplying the precursor electrons required to sustain the plasma.

Hofer, O. C.↗
NASA NTRS1979

Energy budget of the volcano Stromboli, Italy

The results of the analyses of movies of eruptions at Stromboli, Italy, and other available data are used to discuss the question of its energy partitioning among various energy transport mechanisms. Energy is transported to the surface from active volcanoes in at least eight modes, viz. conduction (and convection) of the heat through the surface, radiative heat transfer from the vent, acoustical radiation in blast and jet noise, seismic radiation, thermal energy of ejected particles, kinetic energy of ejected particles, thermal energy of ejected gas, and kinetic energy of ejected gas. Estimated values of energy flux from Stromboli by these eight mechanisms are tabulated. The energy budget of Stromboli in its normal mode of activity appears to be dominated by heat conduction (and convection) through the ground surface. Heat carried by eruption gases is the most important of the other energy transfer modes. Radiated heat from the open vent and heat carried by ejected lava particles also contribute to the total flux, while seismic energy accounts for about 0.5% of the total. All other modes are trivial by comparison.

Mcgetchin, T. R.↗
NASA NTRS1974

Solid medium thermal engine

A device is described which uses a single phase metallic working substance to convert thermal energy directly into mechanical energy. The device consists of a cylindrical metal tube which is free to rotate about its axis while being subjected to continuous bending moment stresses along the longitudinal axis of rotation. The stressing causes portions of the tube to be under compression while other parts are under tension which in turn causes the tube to rotate and provide mechanical energy.

Jedlicka, J. R.↗