Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “weight loss”

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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Effects of tetraamine crosslinking agents on the thermomechanical properties of PMR polyimide composites

The effects were investigated of partial substitution of tetraamine crosslinking agents for diamine reactants on the thermomechanical properties of PMR polyimide resins and graphite fiber-reinforced composites. The effect of tetraamine content on isothermal weight loss, glass transition, and softening temperatures of neat resin samples is discussed. Composites were fabricated using PMR methodology. Monomeric solution of various stoichiometric ratios was used to impregnate Hercules HTS graphite fiber. The mechanical property retention characteristics of the composites at 316 C (600 F) are described.

Delvigs, P.↗
NASA NTRS1976

Metabolic and endocrine studies - The second manned Skylab mission

Complete metabolic collections were performed on the Skylab 3 crew in the preflight, inflight, and postflight phases of the mission. Changes in fluid and electrolyte balance have been correlated with weight loss, changes in the excretion of aldosterone, vasopressin, and fluid compartments. The initial changes observed were consistent with an increase in thoractic blood volume upon transition to a zero gravity environment, producing a net fluid loss. Compensatory mechanisms reestablished positive water balance. The indicators investigated returned to thin preflight levels during the recovery period postflight

Leach, C. S.↗
NASA NTRS1976

Biostereometric analysis of body form - The second manned Skylab mission

Results of biostereometric analyses of the body form of the Skylab 3 crew before and after flight. The Cartesian coordinates of numerous points on the body surface were derived by stereophotogrammetry, and mathematical analysis of the coordinate description allowed computation of the surface area and volume of the body, the volume of body segments, and the area and shape of cross sections. The weight loss in all three crew members was accompanied by a loss in volume distributed between the trunk and legs, with the legs showing the greatest proportional loss. The observed loss of volume apparently resulted from a combined loss of fluid in the abdomen and legs, of muscle in the legs and paraspinal region, and of fat in the abdomen and buttocks.

Whittle, M. W.↗
NASA NTRS1974

Effect of cyclic conditions on the dynamic oxidation of gas turbine superalloys

The effects of operating parameters of a dynamic apparatus used to study oxidation and thermal fatigue of gas turbine materials were studied. IN-100, TD-NiCr, and WI-52 were tested at a maximum temperature of 1,090 deg C. Heating time per cycle was varied from 1/20 hr to 10 hr. Minimum temperatures between heating cycles were room temperature, 430 deg, and 650 deg C. Cooling air velocities were zero, Mach 0.7, and Mach 1. Increasing the number of cycles for a given time at temperature increased weight loss. Thermal fatigue was related to number of cycles more than to time at temperature.

Johnston, J. R.↗
NASA NTRS1977

Physiological mass measurements in Skylab

A spring-mass oscillator constrained to linear motion was used to measure astronaut weight during Skylab mission. Plots of spacecrew body weights, preflight and postflight, and inflight equivalent weight measurements indicate high in-flight metabolic costs with weight losses under weightlessness conditions.

Thornton, W. E.↗
NASA NTRS1976

New aromatic silicon-containing polyamides

The experiments described were aimed at studying systematically the effect of silyl linkages on the thermogravimetric and thermomechanical properties of aromatic polyamides. Specifically, 18 aromatic silicon-containing polyamides were synthesized via interfacial polymerization of six silicon-containing diacid chlorides with 3,3-prime-diaminodiphenylmethane, 3,3-prime-diaminobenzophenone, and 1-(3-prime-aminobenzyl)-4-(3-double prime-aminobenzoyl)benzene. All polyamides were soluble in m-cresol and N,N-dimethylacetamide, and had glass transition temperatures between 178 and 254 C. Thermogravimetric analysis conducted in static air on film specimens showed 5 and 10 percent weight losses between 331 and 400 C and 354 and 440 C, respectively. The potential gain in processability engendered by incorporation of silane substituents was offset in most cases by substantial losses in thermo-oxidative stability.

Pratt, J. R.↗
NASA NTRS1976

Thermal-stress fatigue behavior of twenty-six superalloys

The comparative thermal-stress fatigue resistances of 26 nickeland cobalt-base alloys were determined by fluidized bed tests. Cycles to cracking differed by almost three orders of magnitude for these materials, with directional solidification and surface protection showing definite benefit. The alloy-coating combination with the highest thermal-stress fatigue resistance was directionally solidified NASA TAZ-8A with an RT-SP coating. Its oxidation resistance was also excellent, showing approximately a 1/2 percent weight loss after 14,000 fluidized bed cycles.

Bizon, P. T.↗
NASA NTRS1977

Studies with the Arapahoe smoke chamber

Samples of polymethyl methacrylate, polyvinyl chloride, polyester, and polystyrene were evaluated using the Arapahoe smoke chamber. These same materials had been previously evaluated using the National Bureau of Standards (NBS) smoke chamber. The percent smoke based on initial weight as determined using the Arapahoe smoke chamber appeared to correlate with the maximum specific optical density under flaming conditions as determined using the NBS smoke chamber. In addition, the percent smoke based on weight loss as determined using the Arapahoe smoke chamber appeared to correlate with the maximum specific optical density under nonflaming conditions as determined using the NBS smoke chamber. The Arapahoe smoke chamber also offers the advantage of high sample throughput and the possibility of related studies of smoke particulates.

Hilado, C. J.↗
NASA NTRS1977

Interaction of NaCl(g) and HCl(g) with condensed NA2SO4

The interaction of Na2SO4(l) with NaCl(g), HCl(g) and H2O(g) was studied in atmospheric pressure flowing air and oxygen at Na2SO4(l) temperatures of 900 and 1000 C. Thermomicrogravimetric and high pressure mass spectrometric sampling techniques were used. Experimental results establish that previously reported enhanced rates of weight loss of Na2SO4(l) in the presence of NaCl(g) are due to the reaction: Na2SO4(c) + 2HCl(g) = 2NaCl(g) + SO2(g) + H2O(g) + 1/2O2(g) being driven to the right in flowing gas systems. The HCl(g) is the product of hydrolysis of NaCl caused by small but significant amounts of H2O(g) present in the system. Thermochemical calculations are used to show that even with sub-ppm levels of H2O(g) present, significant quantities of HCl(g) are produced.

Stearns, C. A.↗
NASA NTRS1978

Effect of thermal exposure on lubricating properties of polyimide films and polyimide-bonded graphite fluoride films

The effect of thermal exposure on the weight loss, adherence, friction, and wear properties of polyimide films and polyimide bonded graphite fluoride films was investigated. Films bonded to 304 stainless steel or 440C-HT steel were thermally exposed at temperatures of 315 ,345, 370, or 400 C for 100 hours or more and then evaluated, using a pin-on-disk machine, at temperatures of 25, 315, or 345 C in atmospheres of dry or moist air. Polyimide films were brittle after thermal exposure. Polyimide bonded graphite fluoride films had adherence and gave low friction and wear results; thus, they appear to be good candidates for solid lubrication applications where long thermal soaks are prevalent.

Fusaro, R. L.↗
NASA NTRS1978

Flight service evaluation of Kevlar-49 epoxy composite panels in wide-bodied commercial transport aircraft

Kevlar-49 fairing panels, installed as flight service components on three L-1011s, were inspected after four years' service, and found to be performing satisfactorily. The Kevlar-49 components were all found to be performing satisfactorily in service with no major problems, or any condition requiring corrective action. The only defects noted were minor impact damage, and a minor degree of fastener hole fraying and elongation. These are for the most part comparable to damage noted on fiberglass fairings. A concurrent investigation was conducted on Kevlar-49/epoxy coupons exposed to an outdoor environment over a three year period at various locations providing a variety of climatic conditions. Weight changes and retention of mechanical properties were determined after one and three years exposure. A net weight loss occurred due to ultraviolet effects on the unpainted specimens. Mechanical property retentions were satisfactory with most specimens retaining well over 80% of their original value.

Stone, R. H.↗
NASA NTRS1978

Filtration effects on ball bearing life and condition in a contaminated lubricant

Ball bearings were fatigue tested with a noncontaminated lubricant and with a contaminated lubricant under four levels of filtration. The test filters had absolute particle removal ratings of 3, 30, 49, and 105 microns. Aircraft turbine engine contaminants were injected into the filter's supply line at a constant rate of 125 milligrams per bearing hour. Bearing life and running track condition generally improved with finer filtration. The experimental lives of 3 and 30 micron filter bearings were statistically equivalent, approaching those obtained with the noncontaminated lubricant bearings. Compared to these bearings, the lives of the 49 micron bearings were statistically lower. The 105 micron bearings experienced gross wear. The degree of surface distress, weight loss, and probable failure mode were dependent on filtration level, with finer filtration being clearly beneficial.

Loewenthal, S. H.↗
NASA NTRS1978

Effect of filtration on rolling-element-bearing life in contaminated lubricant environment

Fatigue tests were conducted on groups of 65 millimeter-bore ball bearings under four levels of filtration with and without a contaminated MIL-L-23699 lubricant. The baseline series used noncontaminated oil with 49 micron absolute filtration. In the remaining tests contaminants of the composition found in aircraft engine filters were injected into the filter's supply line at a constant rate of 125 milligrams per bearing-hour. The test filters had absolute particle removal ratings of 3, 30, 49, and 105 microns (0.45, 10, 30, and 70 microns nominal), respectively. Bearings were tested at 15,000 rpm under 4580 newtons radial load. Bearing life and running tract condition generally improved with finer filtration. The 3 and 30 micron filter bearings in a contaminated lubricant had statistically equivalent lives, approaching those from the baseline tests. The experimental lives of 49 micron bearings were approximately half the baseline bearing's lives. Bearings tested with the 105 micron filter experienced wear failures. The degree of surface distress, weight loss, and probable failure mode were found to be dependent on filtration level, with finer filtration being clearly beneficial.

Loewenthal, S. H.↗
NASA NTRS1977

Evaluation of low cost/high temperature fiber and blanket insulation

Twelve fiber materials comprising water-felted fiber cakes and blanket insulation were subjected to furnace exposures at 1000, 1200, 1400, and 1600 C for up to 500 hours to establish the time-temperature limits below which these insulation materials can withstand repeated thermal cycles without detrimental shrinkage, thermal conductivity increase, or physical changes. Test samples were inspected periodically during the exposure cycles and weight loss and dimensional shrinkage were measured. Density, fiber crystallography, and thermal conductivity were measured after exposure and properties were compared with those of unexposed controls.

Strauss, E. L.↗
NASA NTRS1979

Effect of thermal aging on the tribological properties of polyimide films and polyimide-bonded graphite fluoride films

Weight loss, adherence, friction and wear of polyimide films and polyimide-bonded graphite fluoride films applied to stainless steel disks and to 304 stainless steel thin foils were studied. The films were exposed at temperatures of 315 D, 345 D, 370 D, or 400 C for 100 hours or more and then evaluated at temperatures of 25 D, 315 D, or 345 C in atmospheres of dry or moist air. Polyimide films were found to be brittle after thermal exposure; but polyimide-bonded graphite fluoride possessed good adherence and gave low friction and wear results. Polyimide-bonded graphite fluoride films appear to be good candidates for solid lubrication applications where long thermal soaks are prevalent.

Fusaro, R. L.↗
NASA NTRS1979

Effects of graphite fiber stability on the properties of PMR polyimide composites

The effect of the stability of graphite fibers on composite properties after exposure in air at 600 F was investigated. Composites were fabricated from PMR-15 and PMR-2 monomer solutions, using HTS-2 and Celion 6000 graphite fibers as the reinforcement. The effect of long-term exposure in air at 600 F on composite weight loss and mechanical properties was determined. These composites exhibited a significantly increased lifetime at that temperature compared to composites fabricated from HTS fiber sold prior to 1975. The effect of the PMR-15 and PMR-II resin compositions on long-term composite performance at 600 F is also discussed.

Delvigs, P.↗
NASA NTRS1979

Seat test program

The test program has the objectives to: (1) evaluate severity of newspaper ignition source with contemporary seats (determine weight loss, visual damage, and if ignition source is severe enough to show improvement with new material configurations); (2) compare damage with jet A-1 ignition source; and (3) determine if materials for seat tests pass FAR 25 and obtain L01. Test configurations, data acquired, material test results, seat test results, and conclusions are presented.

Bricker, R. W.↗
NASA NTRS1979

Global enclosure fire modeling with applications

A brief review of LERC (Limiting Energy Release Criteria) is presented. Application of LERC to JSC/Boeing ignition source full-scale tests and to JSC/Dacfir math-model validation tests is outlined. It is concluded that: (1) a complete LERC application to the JSC/Boeing tests verifies the fuel load criterion as the limiting constraint; (2) the variability of magnitude and form of the results of repeated tests with and without small variations in parameters emphasizes the significance of the local flow, species concentration, and heat transfer distribution; and (3) weight loss measurements of recent JSC tests show consistent results with prior methods, fuel load constrained.

Stuart, J. W.↗