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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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Temperature and material effects on high-velocity impact craters in phenolic-nylon and elastomeric ablative heat-shield materials
Interdisciplinary materials research including fundamental physics and chemistry of materials, environmental effects and related problems
Material property effects on ablative performance of silica phenolic, graphite phenolic, and graphite epoxy materials
NASA and the FAA established the Computational Materials (CM) for Qualification and Certification (Q&C) steering group comprised of representatives from industry, government regulatory and research organizations, and academia with the following goals: - Inform the research and development investments made by U.S. industry and the U.S. government toward maturation of CM-based approaches for Qualification and Certification (Q&C) of process intensive metallic materials (PIM) including additive manufacturing. - Identify key considerations and enablers required to increase airworthiness / certifying authorities’ acceptance of CM methods use for Q&C of structural or flight-critical parts produced with PIM technologies. - Identify key CM technology gaps and maturation paths (in the context of Q&C applications). - Increase dialogue among stakeholder organizations. This presentation will summarize the technology and regulatory considerations that motivate this national effort, discuss progress and provide a summary and status of a multi-year roadmap that is being developed to guide technology development in this important area.
Materials structures research within framework of mechanical constitutive equation, reviewing fiber reinforced composites from microscopic to macroscopic viewpoints
System fluids, boiler materials, condenser tube to tube sheet joint, turbine rotor and nozzle materials, and mercury corrosion loop program - SNAP-8
Plane elastic waves of finite amplitude in Hadamard materials and harmonic materials
Interdisciplinary materials research in inorganic nonmetallic materials, metallic solids, polymers, and solid state physics
The influence of strength, fracture toughness, and crack growth resistance on the design stress level has been determined from a mathematical model of crack growth and failure. The results show that to select materials properly, the operating parameters of desired life and initial flaw size must be considered simultaneously with the material properties. To do this, a method for constructing an operating surface is derived, discussed, and illustrated.
Procedures for determining fundamental properties of semiconductor materials, their performance as radiation detectors, and their service life as such detectors are given. Relationships were established between the minority carrier lifetime in the bulk of the material and the charge collection efficiency of the detector.
A general forced-vibration analysis is presented for laminated anisotropic rectangular plates including material damping. The theory used is the laminated version of the Mindlin plate theory and includes thickness-shear flexibility and rotatory and coupling inertia. A solution is obtained by the Rayleigh-Ritz method, extended to include the energy dissipated and the work done by the excitation. The analysis is applied to prediction of the resonant frequencies and associated nodal patterns and damping ratios of the first five modes for a series of rectangular plates with free edges. The plates considered consist of unidirectional boron-fiber/epoxy composite material with respective fiber orientations of 0, 10, 30, 45, 60, and 90 deg.
Cyclic creep response was investigated and design methods applicable to thermal protection system structures were developed. The steady-state (constant temperature and load) and cyclic creep response characteristics of four alloys were studied. Steady-state creep data were gathered through a literature survey to establish reference data bases. These data bases were used to develop empirical equations describing creep as a function of time, temperature, and stress and as a basis of comparison for test data. Steady-state creep tests and tensile cyclic tests were conducted. The following factors were investigated: material thickness and rolling direction; material cyclic creep response under varying loads and temperatures; constant stress and temperature cycles representing flight conditions; changing stresses present in a creeping beam as a result of stress redistribution; and complex stress and temperature profiles representative of space shuttle orbiter trajectories. A computer program was written, applying creep hardening theories and empirical equations for creep, to aid in analysis of test data. Results are considered applicable to a variety of structures which are cyclicly exposed to creep producing thermal environments.
The work described, while involving research in the broad field of materials processing, has two common features: the problems are closed related to space precessing of materials and have both practical and fundamental significance. An interesting and important feature of many of the projects is that the interdisciplinary nature of the problem mandates complementary analytical modeling/experimental approaches. An other important aspect of many of the projects is the increasing use of mathematical modeling techniques as one of the research tools. The predictive capability of these models, when tested against measurements, plays a very important role in both the planning of experimental programs and in the rational interpretation of the results. Many of the projects described have a space experiment as their ultimate objective. Mathematical models are proving to be extremely valuable in projecting the findings of ground - based experiments to microgravity conditions.
As a part of the investigation of the control system failure Inertial Upper Stage on IUS-1 flight to position a Tracking and Data Relay Satellite (TDRS) in geosynchronous orbit, the materials utilized in the techroll seal are evaluated for possible failure models. Studies undertaken included effect of temperature on the strength of the system, effect of fatigue on the strength of the system, thermogravimetric analysis, thermomechanical analysis, differential scanning calorimeter analysis, dynamic mechanical analysis, and peel test. The most likely failure mode is excessive temperature in the seal. In addition, the seal material is susceptible to fatigue damage which could be a contributing factor.
The objectives of the Silicon Materials Task and the Advanced Silicon Sheet Task are to identify the critical technical barriers to low-cost silicon purification and sheet growth that must be overcome to produce a PV cell substrate material at a price consistent with Flat-plate Solar Array (FSA) Project objectives and to overcome these barriers by performing and supporting appropriate R&D. Progress reports are given on silicon refinement using silane, a chemical vapor transport process for purifying metallurgical grade silicon, silicon particle growth research, and modeling of silane pyrolysis in fluidized-bed reactors.
The report concludes that an enhanced effort of earth materials research is necessary to advance the understanding of the processes that shape the planet. In support of such an effort, there are new classes of experiments, new levels of analytical sensitivity and precision, and new levels of theory that are now applicable in understanding the physical and chemical properties of geological materials. The application of these capabilities involves the need to upgrade and make greater use of existing facilities as well as the development of new techniques. A concomitant need is for a sample program involving their collection, synthesis, distribution, and analysis.
The values obtained for brightness ratios between contiguous bright and dark areas on Deimos from Viking Orbiter images, together with the lack of a significant wavelength dependence of these ratios in the 0.4-0.6-micron range, are presently noted to be consistent with particle size fraction measurements of the Murchison CM meteorite. These data, and a near-coincidence of Deimos absolute reflectances with those of laboratory samples, render the present data consistent with both brighter and darker materials on Deimos being akin to carbonaceous chondrites; the material with smaller average particle size is associated with the brighter patches.
The paper reviews nonlinear bulk compressional wave acoustic measurement systems and the applications of measurements from such systems to engineering materials. Preliminary measurements indicate that it is possible to determine percent second phase precipitates in aluminum alloys, while other measurements show promise in the determination of properties related to the fatigue states of metals. It is also shown that harmonic generation can be used for the study of crack opening loads in compact tension specimens, which in turn gives useful information about the fatigue properties of various engineering materials.