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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Development of lightweight reinforced plastic laminates for spacecraft interior applications

Lightweight, Kevlar - reinforced laminating systems that are non-burning, generate little smoke in the space shuttle environment, and are physically equivalent to the fiberglass/polyimide system used in the Apollo program for non-structural cabin panels, racks, etc. Resin systems representing five generic classes were screened as matrices for Kevlar 49 reinforced laminates. Of the systems evaluated, the polyimides were the most promising with the phenolics a close second. Skybond 703 was selected as the most promising resin candidate. With the exception of compression strength, all program goals of physical and mechanical properties were exceeded. Several prototype space shuttle mobility and translation handrail segments were manufactured using Kevlar/epoxy and Kevlar-graphite/epoxy. This application shows significant weight savings over the baseline aluminum configuration used previous. The hybrid Kevlar-graphite/epoxy is more suitable from a processing standpoint.

Hertz, J.↗
NASA NTRS1979

Weld bead reinforcement removal: A method of improving the strength and ductility of peaked welds in 2219-T87 aluminum alloy plate

The results of a study to determine the degree to which the ductility and tensile properties of peaked welds could be enhanced by removing the reinforcing bead and fairing the weld nugget into the adjacent parent metal are presented. The study employed 2219-T87 aluminum alloy plate, tungsten inert gas (TIG) welding, and 2319 filler wire. The study concluded that significant improvements in peak weld, ultimate strength, and ductility can be obtained through removal and fairing of the weld reinforcing bead. The specimens so treated and tested in this program exhibited ultimate strength improvements of 2 to 3 percent for peak angles of 5.8 to 10 degrees and 10 to 22 percent for welds with peak angles of 11.7 to 16.9 degrees. It was also determined that removal of the weld bead enhanced the ability of peaked welds to straighten when exposed to cyclic loading at stress levels above the yield strength.

Lovoy, C. V.↗
NASA NTRS1979

Fatigue behavior of SiC reinforced titanium composites

The low cycle axial fatigue properties of 25 and 44 fiber volume percent SiC/Ti(6Al-4V) composites were measured at room temperature and at 650 deg C. The S-N curves for the composites showed no anticipated improvement over bulk matrix behavior at room temperature. Although axial and transverse tensile strength results suggest a degradation in SiC fiber strength during composite fabrication, it appears that the poor fatigue life of the composites was caused by a reduced fatigue resistance of the reinforced Ti(6Al-4V) matrix. The reduced matrix behavior was due, to the presence of flawed and fractured fibers created near the specimen surfaces by preparation techniques and to the large residual tensile stresses that can exist in fiber reinforced matrices. The effects of fatigue testing at high temperature are discussed.

Bhatt, R. T.↗
NASA NTRS1978

Glass matrix composites. I - Graphite fiber reinforced glass

An experimental program is described in which graphite fibers of Hercules HMS and HTS, Thornel 300, and Celanese DG-12 were used to reinforce, both uniaxially and biaxially, borosilicate pyrex glass. Composite flexural strength distribution, strength as a function of test temperature, fracture toughness and oxidative stability were determined and shown to be primarily a function of fiber type and the quality of fiber-matrix bond formed during composite fabrication. It is demonstrated that the graphite fiber reinforced glass system offers unique possibilities as a high performance structural material.

Prewo, K. M.↗
NASA NTRS1979

Tungsten fiber reinforced FeCrAlY - A first generation composite turbine blade material

General and composite turbine blade material requirements are examined to identify a specific tungsten fiber reinforced superalloy (TFRS) having, in addition to strength, the desired combination of other material properties needed in turbine blades. Experimental data indicated that a thoriated tungsten fiber reinforced FeCrAlY matrix composite should have the stress-rupture, creep, tensile, fatigue, and impact strengths required for turbine blades operating from 1250 to 1370 K. Fabrication and design concepts are developed to demonstrate the feasibility of fabricating a hollow TFRS turbine blade at reasonable cost.

Petrasek, D. W.↗
NASA NTRS1979

Material characteristics of Space Shuttle reinforced carbon-carbon

Reinforced carbon-carbon with an oxidation-resistant coating is used as the thermal protection system for the Space Shuttle Orbiter high-temperature wing leading edge and nose cap surfaces. The reinforced carbon-carbon system is capable of multimission reuse, and, in addition, provides a smooth external moldline while transmitting aerodynamic loads to the fuselage forward bulkhead and wing spar through mechanical attachments. This paper describes the material and processes developed, strength and thermal/physical properties which characterize performance.

Curry, D. M.↗
NASA NTRS1979

Optimization of reinforced concrete slabs

Reinforced concrete cells composed of concrete slabs and used to limit the effects of accidental explosions during hazardous explosives operations are analyzed. An automated design procedure which considers the dynamic nonlinear behavior of the reinforced concrete of arbitrary geometrical and structural configuration subjected to dynamic pressure loading is discussed. The optimum design of the slab is examined using an interior penalty function. The optimization procedure is presented and the results are discussed and compared with finite element analysis.

Ferritto, J. M.↗
NASA NTRS1980

Fire test method for graphite fiber reinforced plastics

A potential problem in the use of graphite fiber reinforced resin matrix composites is the dispersal of graphite fibers during accidential fires. Airborne, electrically conductive fibers originating from the burning composites could enter and cause shorting in electrical equipment located in surrounding areas. A test method for assessing the burning characteristics of graphite fiber reinforced composites and the effectiveness of the composites in retaining the graphite fibers has been developed. The method utilizes a modified rate of heat release apparatus. The equipment and the testing procedure are described. The application of the test method to the assessment of composite materials is illustrated for two resin matrix/graphite composite systems.

Bowles, K. J.↗
NASA NTRS1980

Methods for an investigation of the effect of material components on the mechanical characteristics of glass-fiber-reinforced plastics

The materials used in the production of glass reinforced plastics are discussed. Specific emphasis is given to matrix polyester materials, the reinforcing glass materials, and aspects of specimen preparation. Various methods of investigation are described, giving attention to optical impregnation and wetting measurements and the gravimetric determination of the angle of contact. Deformation measurements and approaches utilizing a piezoelectric device are also considered.

Willax, H. O.↗
NASA NTRS1980

Research on graphite reinforced glass matrix composites

High levels of mechanical performance in tension, flexure, fatigue, and creep loading situations of graphite fiber reinforced glass matrix composites are discussed. At test temperatures of up to 813 K it was found that the major limiting factor was the oxidative instability of the reinforcing graphite fibers. Particular points to note include the following: (1) a wide variety of graphite fibers were found to be comparable with the glass matrix composite fabrication process; (2) choice of fiber, to a large extent, controlled resultant composite performance; (3) composite fatigue performance was found to be excellent at both 300 K and 703 K; (4) composite creep and stress rupture at temperatures of up to 813 K was limited by the oxidative stability of the fiber; (5) exceptionally low values of composite thermal expansion coefficient were attributable to the dimensional stability of both matrix and fiber; and (6) component fabricability was demonstrated through the hot pressing of hot sections and brazing using glass and metal joining phases.

Prewo, K. M.↗
NASA NTRS1980

Computational models for the nonlinear analysis of reinforced concrete plates

A finite element computational model for the nonlinear analysis of reinforced concrete solid, stiffened and cellular plates is briefly outlined. Typically, Mindlin elements are used to model the plates whereas eccentric Timoshenko elements are adopted to represent the beams. The layering technique, common in the analysis of reinforced concrete flexural systems, is incorporated in the model. The proposed model provides an inexpensive and reasonably accurate approach which can be extended for use with voided plates.

Hinton, E.↗
NASA NTRS1979

Fatigue behavior of SiC reinforced titanium composites

The low cycle axial fatigue properties of 25 and 44 fiber volume percent SiC/Ti(6Al-4V) composites were measured at room temperature and at 650 C. At room temperature, the S-N curves for the composites showed no anticipated improvement over bulk matrix behavior. Although axial and transverse tensile strength results suggest a degradation in SiC fiber strength during composite fabrication, it appears that the poor fatigue life of the composites was caused by a reduced fatigue resistance of the reinforced Ti(6Al-4V) matrix. Microstructural studies indicate that the reduced matrix behavior was due, in part, to the presence of flawed and fractured fibers created near the specimen surfaces by preparation techniques. Another possible contributing factor is the large residual tensile stresses that can exist in fiber-reinforced matrices. These effects, as well as the effects of fatigue testing at high temperature, are discussed.

Bhatt, R. T.↗
NASA NTRS1980

Fire test method for graphite fiber reinforced plastics

A potential problem in the use of graphite fiber reinforced resin matrix composites is the dispersal of graphite fibers during accidental fires. Airborne, electrically conductive fibers originating from the burning composites could enter and cause shorting in electrical equipment located in surrounding areas. A test method for assessing the burning characteristics of graphite fiber reinforced composites and the effectiveness of the composites in retaining the graphite fibers has been developed. The method utilizes a modified Ohio State University Rate of Heat Release apparatus. The equipment and the testing procedure are described. The application of the test method to the assessment of composite materials is illustrated for two resin matrix/graphite composite systems.

Bowles, K. J.↗
NASA NTRS1979

Glass fiber reinforced concrete for terrestrial photovoltaic arrays

The use of glass-fiber-reinforced concrete (GRC) as a low-cost structural substrate for terrestrial solar cell arrays is discussed. The properties and fabrication of glass-reinforced concrete structures are considered, and a preliminary design for a laminated solar cell assembly built on a GRC substrate is presented. A total cost for such a photovoltaic module, composed of a Korad acrylic plastic film front cover, an aluminum foil back cover, an ethylene/vinyl acetate pottant/adhesive and a cotton fabric electrical isolator in addition to the GRC substrate, of $9.42/sq m is projected, which is less than the $11.00/sq m cost goal set by the Department of Energy. Preliminary evaluations are concluded to have shown the design capabilities and cost effectiveness of GRC; however, its potential for automated mass production has yet to be evaluated.

Maxwell, H.↗
NASA NTRS1982

Designing with figer-reinforced plastics (planar random composites)

The use of composite mechanics to predict the hygrothermomechanical behavior of planar random composites (PRC) is reviewed and described. These composites are usually made from chopped fiber reinforced resins (thermoplastics or thermosets). The hygrothermomechanical behavior includes mechanical properties, physical properties, thermal properties, fracture toughness, creep and creep rupture. Properties are presented in graphical form with sample calculations to illustrate their use. Concepts such as directional reinforcement and strip hybrids are described. Typical data that can be used for preliminary design for various PRCs are included. Several resins and molding compounds used to make PRCs are described briefly. Pertinent references are cited that cover analysis and design methods, materials, data, fabrication procedures and applications.

Chamis, C. C.↗
NASA NTRS1982

Fuselage structure using advanced technology fiber reinforced composites

A fuselage structure is described in which the skin is comprised of layers of a matrix fiber reinforced composite, with the stringers reinforced with the same composite material. The high strength to weight ratio of the composite, particularly at elevated temperatures, and its high modulus of elasticity, makes it desirable for use in airplane structures.

Robinson, R. K.↗
NASA NTRS1982

Reinforcing aluminum alloys with high strength fibers

A study is made of the possibility of reinforcing aluminum and aluminum based alloys with fibers made of high strength steel wire. The method of introducing the fibers is described in detail. Additional strengthening by reinforcement of the high alloy system Al - An - Mg was investigated.

Kolpashnikov, A. I.↗
NASA NTRS1982

Prospects of increasing the strength of aluminum by reinforcing it with stainless steel wire (a review)

The theoretical and experimental strength of aluminum reinforced with stainless steel wire is analyzed. Various methods of producing the composite material and it's static and cyclical strengths are considered. The reinforcement of aluminum with stainless steel wire was accomplished from the perspective of increasing the specific strength of aluminum and it's alloys, increasing the strength of the material with respect to high and low temperatures, as well as increasing the cyclical strength. The production of the composite aluminum-stainless steel wire material with approximated or calculated strengthening is possible by any of the considered methods. The selection of the proper production technology depends on precise details and conditions of application of the material.

Botvina, L. R.↗