Lapas attēli

demonstrate the capability of the conventional ultrasonics and EMAT technologies to detect a thinning or cracked wall. Recommendations for additional eddy current and EMAT development tests are presented.


chamber. The gas density, pressure, and flux at any location in the flow field are calculated based on the vent plume description and the knowledge of the flow rate and velocity of the venting gas. The same parameters and the column densities along a specified line of sight traversing the plume are also obtained and shown by a computer-generated graphical representation. The fields obtained with a radially scanning Pitot probe within the exhausting gas are described by a power of the cosine function, the mass rate and the distance from the exit port. The field measurements were made for gas at pressures ranging from 2 to 50 torr venting from pipe fittings with diameters of 3/16 inch to 1-1/2 inches I.D. (4.76 mm to 38.1 mm). The N(2) mass flow rates ranged from 2E-4 to 3.7E-1 g/s.


N89-26900* # SECA, Inc., Huntsville, AL. INVESTIGATION OF THE TRANSIENT FUEL PREBURNER MANIFOLD AND COMBUSTOR Final Report Ten-See Wang, Yen-Sen Chen, and Richard C. Farmer Jun. 1989 89 p (Contract NAS8-37461) (NASA-CR-183715; NAS 1.26:183715; SECA-89-10) Avail: NTIS HC A05/MF A01 CSCL 21H

A computational fluid dynamics (CFD) model with finite rate reactions, FDNS, was developed to study the start transient of the Space Shuttle Main Engine (SSME) fuel preburner (FPB). FDNS is a time accurate, pressure based CFD code. An upwind scheme was employed for spatial discretization. The upwind scheme was based on second and fourth order central differencing with adaptive artificial dissipation. A state of the art two-equation k-epsilon (T) turbulence model was employed for the turbulence calculation. A Pade' Rational Solution (PARASOL) chemistry algorithm was coupled with the point implicit procedure. FDNS was benchmarked with three well documented experiments: a confined swirling coaxial jet, a non-reactive ramjet dump combustor, and a reactive ramjet dump combustor. Excellent comparisons were obtained for the benchmark cases. The code was then used to study the start transient of an axisymmetric SSME fuel preburner. Predicted transient operation of the preburner agrees well with experiment. Furthermore, it was also found that an appreciable amount of unburned oxygen entered the turbine stages.


N89-26903*# Cummings (Robert L.), Litchfield, OH.
TURBINE Final Report
Robert L. Cummings Aug. 1989 35 p
(NASA Order C-22187-M)
(NASA-CR-182263; E-4657; NAS 1.26:182263) Avail: NTIS HC
A03/MF A01 CSCL 21H

The methods which have been used by the NASA Lewis Research Center for predicting Brayton Cycle compressor and turbine performance for different gases and flow rates are described. These methods were developed by NASA Lewis during the early days of Brayton cycle component development and they can now be applied to the task of predicting the performance of the Closed Brayton Cycle (CBC) Space Station Freedom power system. Computer programs are given for performing these calculations and data from previous NASA Lewis Brayton Compressor and Turbine tests is used to make accurate estimates of the compressor and turbine performance for the CBC power system. Results of these calculations are also given. In general, calculations confirm that the CBC Brayton Cycle contractor has made realistic compressor and turbine performance estimates.


N89-26901*# Morton Thiokol, Brigham City, UT. Aerospace
TEST REPORT Final Report
M. Cook 11 May 1989 41 p
(Contract NAS8-30490)
(NASA-CR-183702; NAS 1.26:183702; TWR-18076;
WBS-4B102-10-03; ECS-SS1323) Avail: NTIS HC A03/MF
A01 CSCL 21H

This report documents the procedures, performance, and results obtained from the Field Joint Protection System (FJPS) rain test. This test was performed to validate that the flight configuration FJPS prevents the accumulation of moisture in the redesigned solid rocket motor (RSRM) field joints when subjected to simulated prelaunch natural rain environments. The FJPS test article was exposed to rain simulation for approximately 50 minutes. During the test, water entered through the open upper end of the systems tunnel and was funneled down between the tunnel and case. A sealant void at the moisture seal butt splice allowed this water to flow underneath the FJPS. The most likely cause of voids was improper bondline preparation, particularly on the moisture seal surface. In total, water penetrated underneath approximately 60 percent of the FJPS circumference. Because the test article was substantially different from flight configuration (no systems tunnel closeout), results of this test will not affect current flight motors. Due to the omission of systems tunnel covers and systems tunnel floor plate closeout, the test assembly was not representative of flight hardware and resulted in a gross overtest. It is therefore recommended that the test be declared void. It is also recommended that the test be repeated with a complete closeout of the systems tunnel, sealed systems tunnel ends, and improved adhesive bondline preparation. Author

N89-26904* # National Aeronautics and Space Administration.
Lewis Research Center, Cleveland, OH.
John L. Power and Randall A. Chapman 1989 26 p Presented
at the 24th Microwave Power Symposium, Stanford, CT, 21-23
Aug. 1989; sponsored by the International Microwave Power Inst.
(NASA-TM-102321; E-5017; NAS 1.15:102321) Avail: NTIS HC
A03/MF A01 CSCL 21H

This paper describes the current development of a high-power microwave electrothermal thruster (MET) concept at the NASA Lewis Research Center. Such a thruster would be employed in space for applications such as orbit raining, orbit maneuvering, station change, and possibly trans-lunar or trans-planetary propulsion of spacecraft. The MET concept employs low frequency continuous wave (CW) microwave power to create and continuously pump energy into a flowing propellant gas at relative high pressure via a plasma discharge. The propellant is heated to very high bulk temperatures while passing through the plasma discharge region and then is expanded through a throat-nozzle assembly to produce thrust, as in a conventional rocket engine. Apparatus, which is described, is being assembled at NASA Lewis to test the MET concept to CW power levels of 30 kW at a frequency of 915 MHz. The microwave energy is applied in a resonant cavity applicator and is absorbed by a plasma discharge in the flowing propellant. The ignited plasma acts as a lossy load, and with optimal tuning, energy absorption efficiencies over 95 percent (based on the applied microwave power) are expected. Nitrogen, helium, and hydrogen will be tested as propellants in the MET, at discharge chamber pressures to 10 atm.


N89-26902*# National Aeronautics and Space Administration.
Goddard Space Flight Center, Greenbelt, MD.
John J. Scialdone Washington Jul. 1989 15 p
(NASA-TM-100738; NAS 1.15:100738; Rept-89B00151) Avail:

The flow field produced by low pressure gas vents are described based on experimental data obtained from tests in a large vacuum

111 p

N89-26905* Rockwell International Corp., Canoga Park, CA.
Rocketdyne Div.
G. L. Briley and R. S. lacabucci Nov. 1988
(Contract NAS3-25142)
(NASA-CR-182280; NAS 1.26:182280; RI/RD88-256) Avail:
Issuing Activity CSCL 21H

The effort expended by the Rocketdyne Division of Rockwell International in fulfilling the requirements of the Space Station Freedom Hydrogen/Oxygen Thruster Technology program is discussed. Included are the basis and the rationale for the design of the thruster, injector, and nozzle; the test results; and the lessons learned, together with conclusions and recommendations for the development of the Space Station Freedom thrusters. Author

US-Patent-Class-228-194) Avail: US Patent and Trademark
Office CSCL 11/6

A method for fabricating an improved titanium alloy composite consisting of a least one high strength/high stiffness filament or fiber embedded in an alpha-beta titanium alloy matrix which comprises the steps of providing a rapidly-solidified foil made of a rich metastable beta titanium alloy, fabricating a preform consisting of alternating layers of the rapidly-solidified foil and the filamentary material, and applying heat and pressure to consolidate the preform, wherein consolidation is carried out at a temperature below the beta-transus temperature of the alloy.


5 p

N89-26906*# National Aeronautics and Space Administration. Lewis Research Center, Cleveland, OH. ELECTRIC PROPULSION OPTIONS FOR 10 kW CLASS EARTH SPACE MISSIONS M. J. Patterson and Francis M. Curran May 1989 29 p Presented at the JANNAF Propulsion Meeting, Cleveland, OH, 23-25 May 1989 (NASA-TM-102337; E-5046; NAS 1.15:102337) Avail: NTIS HC A03/MF A01 CSCL 21C

Five and 10 kW ion and arcjet propulsion system options for a near-term space demonstration experiment have been evaluated. Analyses were conducted to determine first-order propulsion system performance and system component mass estimates. Overall mission performance of the electric propulsion systems was quantified in terms of the maximum thrusting time, total impulse, and velocity increment capability available when integrated onto a generic spacecraft under fixed mission model assumptions. Maximum available thrusting times for the ion-propelled spacecraft options, launched on a DELTA || 6920 vehicle, range from approximately 8,600 hours for a 4-engine 10 kW system to more than 29,600 hours for a single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 1.2x10(7) to 2.1x10(7) N-s, and 3550 to 6200 m/s, respectively. Maximum available thrusting times for the arcjet propelled spacecraft launched on the DELTA II 6920 vehicle range from approximately 528 hours for the 6-engine 10 kW hydrazine system to 2328 hours for the single-engine 5 kW system. Maximum total impulse values and maximum delta-v's range from 2.2x10(6) to 3.6x10(6) N-s, and approximately 662 to 1072 m/s, respectively. Author

N89-26908 Department of the Air Force, Washington, DC.
Daniel Eylon, inventor (to AF) and Francis H. Froes, inventor (to
AF) 28 Feb. 1989

Filed 26 Nov. 1986 Supersedes
(AD-D014065; US-Patent-4,807,798; US-Patent-Appl-SN-935362;
US-Patent-Class-288-190) Avail: US Patent and Trademark
Office CSCL 11/4

A method for fabricating an improved titanium alloy composite consisting of at least one high strength/high stiffness filament or fiber embedded in an alpha-beta titanium alloy matrix which comprises the steps of providing a rapidly-solidified foil made of a lean metastable beta titanium alloy, fabricating a preform consisting of alternating layers of the rapidly-solidified foil and the filamentary material, and applying heat and pressure to consolidate the preform, wherein consolidation is carried out at a temperature below the beta-transus temperature of the alloy.


N89-26909# Army Lab. Command, Watertown, MA. Material
Technology Lab.
FIBERS Final Report
Elizabeth C. Goeke and Shun-Chin Chou Feb. 1989 72 p
(AD-A207277; MTL-TR-89-16) Avail: NTIS HC A04/MF A01
CSCL 11/2

The Single Fiber Graphite Tester was developed to measure the failure load and fiber diameter of graphite fibers. Data have been taken on a number of commercially available fibers with the tester. These data have been examined in order to understand the dispersion in these properties and the correlation between them.




No abstracts in this category.


Includes physical, chemical, and mechanical properties of laminates and other composite materials.

For ceramic materials see 27 Nonmetallic Materials.

N89-26910# Foster-Miller Associates, Inc., Waltham, MA. INTERFACE MODIFIED GLASS FIBER/THERMOPLASTIC MATRIX COMPOSITES Progress Report, 1 Oct. 1988 - 1 Mar. 1989 Robert F. Kovar and Richard W. Lusignea 1 Mar. 1989 14 p (Contract N00014-88-C-0725) (AD-A207308; NAV-0125-FM-8945-182; CDRL-0001AB) Avail: NTIS HC A03/MF A01 CSCL 11/4

This Phase 1 SBIR program is applying a proprietary interface-modification process to improve the interaction between glass fibers and thermoplastic resin composite matrices. In our accomplishments thus far, we have selected PEEK as the thermoplastic matrix resin and chosen three candidate interface-modifier resins. Fiber wetting experiments will determine which of these candidates is best suited for use on the program. A glass fiber tow spreader that effectively separates the tow into a narrow ribbon of fibers was constructed. Extraction experiments have demonstrated that the oil-based, PEEK compatible sizing can be effectively removed from glass fibers without damage by extraction with an appropriate solvent. Equipment was constructed for winding separated glass tow onto a large diameter drum, then processing the separated tow to remove the present sizing and coat with interface-modifier resin solution while the fibers remain in place upon the drum. Coated fibers will also be staged-dried and heat-treated in place, forming interface-modified glass fibers that have been protected from abrasive damage during the entire interface-modification process.


[blocks in formation]

N89-26911 Department of the Air Force, Washington, DC.
Daniel Eylon, inventor (to AF) and Francis H. Froes, inventor (to
AF) 18 Apr. 1989 4p Filed 1 Feb. 1988
(AD-D014111; US-Patent-4,822,432; US-Patent-Appl-SN-150677)
Avail: US Patent and Trademark Office CSCL 11/4

A method for improving the microstructure of consolidated titanium alloy metal matrix composites which comprises the steps of: (1) heating the composite to a temperature in the range of 800 to 2000 F, the temperature being below the temperature at which interfacial reactions occur between the metal matrix and the fiber, and diffusing hydrogen into the composite to achieve a hydrogen level of about 0.50 to 1.50 weight percent; (2) altering the temperature of the composite to a transformation temperature at or near the temperature of transformation of (HCP) alpha in the hydrogenated composite to (BCC) beta; (3) cooling the composite to room temperature; (4) heating the thus-cooled composite to a temperature below the transformation temperature, and diffusing hydrogen out from the composite; and (5) cooling the composite to room temperature.


(PB89-180376; NISTIR-88/4016) Avail: NTIS HC A04/MF A01 CSCL 11D

A draft standard is given for identification of polymer matrix composite materials and for reporting test results. The draft standard is based on a comprehensive description of the flow of data through the polymer matrix composites community. Two essentially different kinds of data bases are required, one oriented toward a particular group of data users, and one designed to make the collection of all kinds of data straightforward. An interactive dictionary to serve as a tool in the development of the best names is described. Relationships of the draft standard to various groups concerned with composites are noted. Author

N89-26915# California Univ., Davis. Dept. of Chemical Engineering. PROCESSING OF CONTINUOUS FIBER COMPOSITES Final Report Brian G. Higgins, Robert Powell, and You-Lo Hsieh Feb. 1989 32 p (Contract W-7405-eng-48) (DE89-012608; UCRL-21206) Avail: NTIS HC A03/MF A01

This report covers the first year progress in the four main areas of this project. The goals of this project are: the characterization of single carbon fibers by wetting studies and SEM; the kinetics of impregnation into carbon fiber bundles tows (axial and normal); the factors affecting void formation in carbon fiber composites; and process simulations and optimization.


N89-26912*# National Aeronautics and Space Administration.
Lewis Research Center, Cleveland, OH.
D. A. Saravanos and C. C. Chamis 1989 30 p Prepared for
presentation at the Design Automation Conference, Montreal,
Quebec, 17-20 Sep. 1989; sponsored by ASME
(NASA-TM-102094; E-4875; NAS 1.15:102094) Avail: NTIS HC
A03/MF A01 CSCL 11D

A method is developed for the optimal design of composite links based on dynamic performance criteria directly related to structural modal damping and dynamic stiffness. An integrated mechanics theory correlates structural composite damping to the parameters of basic composite material systems, laminate parameters, link shape, and modal deformations. The inclusion of modal properties allows the selective minimization of vibrations associated with specific modes. Ply angles and fiber volumes are tailored to obtain optimal combinations of damping and stiffness. Applications to simple composite links indicate wide margins for trade-offs and illustrate the importance of various design variables to the optimal design.


N89-26916# Oak Ridge National Lab., TN. STATISTICS OF FRACTURE IN TWO GRADES OF ISOTROPIC GRAPHITE C. R. Kennedy and Suzanne Montgomery 1989 3 p Presented at the 19th Biennial Conference on Carbon, University Park, PA, 25 Jun. 1989 (Contract DE-AC05-840R-21400) (DE89-013703; CONF-890627-1) Avail: NTIS HC AO2/MF A01

A test program to determine the flexure strength of graphite grades 2020 and IG-11 has been accomplished. Within three billets of each grade, bend samples were taken from three different orientations in three separate positions. The test data were statistically evaluated using one-way and two-way analyses of variance. Using Bartlett's test, homogeneity of variance for strength was clearly a tenable hypothesis of the 27 separate populations for both graphite grades.


56 p

N89-26913# Argonne National Lab., IL. EROSION OF AI AND AI/SIC W. Wu, K. C. Goretta, P. K. Rohatgi, S. Mostovoy (Illinois Inst. of Tech., Chicago.), and J. L. Routbort Feb. 1989 12 p Presented at the Industry-University Advanced Materials Conference, Denver, CO, 6-9 Mar. 1989 (Contract W-31-109-eng-38) (DE89-013623; CONF-890306-4) Avail: NTIS HC A03/MF A01

Aluminum-matrix composites are being developed for a variety of applications. In some of the applications, the composites may be subjected to erosion by solid particles. Previous studies of erosion of metal-matrix composites have shown that erosion rates are generally higher for the composites than for the unreinforced matrix. Increased erosion has been ascribed to the low ductility inherent in the composite materials. The effect of reduced ductility is especially strong for whisker-reinforced composites. This work was undertaken to investigate systematically solid-particle erosion of a common composite: cast 2014 Al containing particulate Sic. To further elucidate the mechanisms for erosion and the materials parameters affecting erosion rate, the alloys were examined in the as-received and heat-treated conditions.


N89-26917* # Planning Research Corp., Hampton, VA. Aerospace
Technologies Div.
Tan-Hung Hou, Gene J. W. Hou, and Jeen S. Sheen (Old Dominion
Univ., Norfolk, VA.) Jul. 1989

Presented at the AIAA/ASME/ASCE/AHS 28th Structures, Structural Dynamics and Materials Conference, Monterey, CA, 6-8 Apr. 1987 Submitted for publication (Contract NAS1-18000; NAG1-561) (NASA-CR-181866; NAS 1.26:181866; AIAA-87-0751-CP) Avail: NTIS HC A04/MF A01 CSCL 11D

Fiber-reinforced composite laminates are used in many aerospace and automobile applications. The magnitudes and durations of the cure temperature and the cure pressure applied during the curing process have significant consequences for the performance of the finished product. The objective of this study is to exploit the potential of applying the optimization technique to the cure cycle design. Using the compression molding of a filled polyester sheet molding compound (SMC) as an example, a unified Computer Aided Design (CAD) methodology, consisting of three uncoupled modules, (i.e., optimization, analysis and sensitivity calculations), is developed to systematically generate optimal cure cycle designs. Various optimization formulations for the cure cycle design are investigated. The uniformities in the distributions of the temperature and the degree with those resulting from conventional isothermal processing conditions with pre-warmed platens.

N89-26914# National Inst. of Standards and Technology,
Gaithersburg, MD. Polymers Div.
Darrell H. Reneker, John M. Crissman, and Donald L. Hunston
Feb. 1989 62 p

Recommendations with regards to further research in the computerization of the cure cycle design are also addressed.


developed to contain corrosive gas mixtures up to 400 psig and 300 F. The goal of this research project was to develop a lightweight, thin-walled, composite pressure vessel with an 11d aspect ratio of 42 capable of containing hydrogen fluoride and chlorine trifluoride. The vessel was to have a crown radius approaching infinity, a desired knuckle radius approaching zero, and a desired wall thickness of 0.023 in. In this paper the problems encountered and the iterative solutions in addition to the design, analysis, and fabrication of the vessel are presented. DOE

18 p

N89-26918* # National Aeronautics and Space Administration.
Goddard Space Flight Center, Greenbelt, MD.
Yury Flom, B. H. Parker, and H. P. Chu Washington Aug. 1989

Presented at the 21st International SAMPE Technical
Conference, Atlantic City, NJ, 26-28 Sep. 1989
(NASA-TM-100745; NAS 1.15:100745; Rept-89B00215) Avail:

An experimental study was conducted to evaluate fracture toughness of SIC/Al metal matrix composite (MMC). The material was a 12.7 mm thick extrusion of 6061-T6 aluminum alloy with 40 vlo Sic particulates. Specimen configuration and test procedure conformed to ASTM E399 Standard for compact specimens. It was found that special procedures were necessary to obtain fatigue cracks of controlled lengths in the preparation of precracked specimens for the MMC material. Fatigue loading with both minimum and maximum loads in compression was used to start the precrack. The initial precracking would stop by self-arrest. Afterwards, the precrack could be safely extended to the desired length by additional cyclic tensile loading. Test results met practically all the E399 criteria for the calculation of plane strain fracture toughness of the material. A valid K sub IC value of the SiC/Al composite was established as K sub IC 8.9 MPa square root of m. The threshold stress intensity under which crack would cease to grow in the material was estimated as delta k sub th = 2MPa square root of m for R = 0.09 using the fatigue precracking data. Fractographic examinations show that failure occurred by the micromechanism involved with plastic deformation although the specimens broke by brittle fracture. The effect of precracking by cyclic loading in compression on fracture toughness is included in the discussion.


N89-26921# Sandia National Labs., Albuquerque, NM.
T. Bein, K. Brown (New Mexico Univ., Albuquerque.), and C. J.
Brinker 1989 10 p Presented at the 8th International Zeolite
Conference, Amsterdam, Netherlands, 10 Jul. 1989
(Contract DE-AC04-76DP-00789; NSF DMR-87-06167)
(DE89-009831; SAND-89-0664C; CONF-890705-2) Avail: NTIS
HC A02/MF A01

Inorganic thin films with molecular sieving properties have been formed by embedding microcrystals of zeolite Y and chabazite in a glassy silica matrix. The silica matrix was derived from sols prepared from tetraethylorthosilicate hydrolyzed under either acidic or basic conditions in alcoholic solution. Dip-coating, deposition of suspensions, or coating of zeolite dispersions with the glassy silica matrix were used to create the zeolite-silica films. The access of different probe molecules into the zeolitic part of the thin film was examined with in situ Fourier transform infrared radiation (FTIR) techniques and temperature-programmed-desorption studies. With all combinations of deposition techniques and silica matrices, the resulting films showed the molecular sieving properties of the parent zeolite.


28 p

N89-26919*# National Aeronautics and Space Administration.
Lewis Research Center, Cleveland, OH.
D. A. Saravanos and C. C. Chamis Aug. 1989 28 p Submitted
for publication
(NASA-TM-102107; E-4874; NAS 1.15:102107) Avail: NTIS HC
A03/MF A01 CSCL 110

An integrated micromechanics methodology for the prediction of damping capacity in fiber-reinforced polymer matrix unidirectional composites has been developed. Explicit micromechanics equations based on hysteretic damping are presented relating the on-axis damping capacities to the fiber and matrix properties and volume fraction. The damping capacities of unidirectional composites subjected to off-axis loading are synthesized from thermal effect on the damping performance of unidirectional composites due to temperature and moisture variations is also modeled. The damping contributions from interfacial friction between broken fibers and matrix are incorporated. Finally, the temperature rise in continuously vibrating composite plies is estimated. Application examples illustrate the significance of various parameters on the damping performance of unidirectional and off-axis fiber reinforced composites.


N89-26922# Sandia National Labs., Livermore, CA. Structural
Mechanics Div.
V. Trinh and L. I. Weingarten Mar. 1989

Presented at the Joint ASME/JSME Pressure Vessel and Piping Conference, Honolulu, HI, 23-27 Jul. 1989 (Contract DE-AC04-76DR-00789) (DE89-010553; SAND-88-8935; CONF-890721-26) Avail: NTIS HC A03/MF A01

A combined experimental and analytical program has been developed to examine the structural dynamic response of pressurized composite bottles subjected to spatially localized loadings. These bottles were constructed from graphite/epoxy, Kevlar/epoxy and fiberglass/epoxy. Some bottles also contained mock solid propellant. The impulsive, exponentially decaying shock loads were applied using blast tube techniques. Dynamic response analyses of the bottles were performed using the finite element code ABAQUS. A damage model was developed to account for material degradations due to the progressive failures of the composite material. The report presents the comparisons between results obtained from experiments and analytical methods. DOE

13 p

N89-26920# Sandia National Labs., Livermore, CA. Component
Research Div.
C. A. LaJeunesse, K. V. Trinh, J. J. Bartel, and J. R. Spingarn
Oct. 1988

Presented at the Joint ASME/JSME Pressure Vessel and Piping Conference, Honolulu, HI, 23-27 Jul. 1989 (Contract DE-AC04-76DR-00789) (DE89-002536; SAND-88-8934; CONF-890721-1) Avail: NTIS HC A03/MF A01

A graphite/polyimide composite pressure vessel has been

N89-26923# Los Alamos National Lab., NM. SIC-MOSI COMPOSITES David H. Carter, John J. Petrovic, Richard E. Honnell, and W. Scott Gibbs Jun. 1989 (Contract W-7405-eng-36) (DE89-013656; LA-11577-MS) Avail: NTIS HC A03/MF A01

Previous studies have shown that SiC whisker-reinforced MoSi sub 2 is an excellent candidate material for structural use at elevated temperatures. The yield strength at 1400 C was doubled with the addition of Los Alamos VLS SIC whiskers, and increased by a factor of five with the addition of VS SIC whiskers, despite a non-optimal distribution of the reinforcement resulting from dry blending fabrication procedures. A more optimal wet processing technique, providing a much more uniform distribution of the whisker reinforcement will be discussed. Activities directed at alloying MoSi sub 2 with other silicides to improve the mechanical properties of the matrix material will also be described.


26 p

21 p

N89-26924* # National Aeronautics and Space Administration.
Lewis Research Center, Cleveland, OH.
P. L. N. Murthy, D. A. Hopkins, and C. C. Chamis Jul. 1989

Presented at the 3rd Joint Mechanics Conference, San Diego, CA, 9-12 Jul. 1989; sponsored in part by ASCE and ASME (NASA-TM-102302; E-4982; NAS 1.15:102302) Avail: NTIS HC A03/MF A01 CSCL 11D

Recent efforts in computational mechanics methods for simulating the nonlinear behavior of metal matrix composites have culminated in the implementation of the Metal Matrix Composite Analyzer (METCAN) computer code. In METCAN material nonlinearity is treated at the constituent (fiber, matrix, and interphase) level where the current material model describes a time-temperature-stress dependency of the constituent properties in a material behavior space. The composite properties are synthesized from the constituent instantaneous properties by virtue of composite micromechanics and macromechanics models. The behavior of metal matrix composites depends on fabrication process variables, in situ fiber and matrix properties, bonding between the fiber and matrix, and/or the properties of an interphase between the fiber and matrix. Specifically, the influence of in situ matrix strength and the interphase degradation on the unidirectional composite stress-strain behavior is examined. These types of studies provide insight into micromechanical behavior that may be helpful in resolving discrepancies between experimentally observed composite behavior and predicted response.


1 Mar. 1989 29 p Presented at the 12th International Colloquium of the Dynamics of Explosions and Reactive Systems, Ann Arbor, MI, 23-28 Jul. 1988 (Contract W-7405-eng-48) (DE89-008801; UCRL-100490; CONF-8807160-1) Avail: NTIS HC A03/MF A01

Liquid hydrocarbon fuels are used extensively in propulsion systems, and explosion hazards associated with fuel vapors mixed with air must be assessed. In this paper, the detonation of gas phase mixtures of n-hexane and the commercial fuel, JP-4, with oxidizers varying from pure oxygen to air, were studied both experimentally and theoretically via kinetic modeling. Experiments were carried out in a detonation tube 150 mm in diameter and 1.75 m long. Detonation velocities and cell sizes (lambda) were measured as a function of stoichiometry and diluent concentration. The theoretical model calculates the induction length (lambda) of a one-dimensional Zeldovich-von Neumann-Doring (ZND) detonation using the detailed kinetics for the reaction of the hydrocarbon fuel used. The theoretical prediction for the cell size of n-hexane is found to agree well with the experimental data. Because n-hexane is the principal component of JP-4, this fuel would be expected to behave similarly to n-hexane. This similarity is confirmed experimentally. Critical energy and critical tube diameter are compared for a relative measure of the detonability of the heavy hydrocarbon fuels studied, and it appears from kinetic modeling that the detonation sensitivity increases slightly with increasing carbon number; however, this trend cannot be distinguished experimentally with the

in cell size measurement.



17 p

N89-26925# Army Materials Technology Lab., Watertown, MA.
Edward M. Wu (Naval Postgraduate School, Monterey, CA.) and
Shun-Chin Chou Apr. 1989 26 p Repr. from Special Technical
Publication (Philadelphia, PA), 1988
(AD-A208316; MTL-TR-89-30) Avail: NTIS HC A03/MF A01
CSCL 11/4

The reliability of a composite structure depends on the materials strength variability. Unidirectional composites fail sequentially initiating from the very weakest fiber sites with matrix binder providing local redundancy by transferring load to neighboring fibers until cumulation and clustering of these sites lead to severe stress concentration and ultimate structure failure. As a consequence, the variability of the metal matrix structure is traceable to the strength variability of the constituent fiber, the metal matrix coating process, and the composite wire consolidation process. This report focuses on the partitioning of the first two sources of variability, identification and modeling of the dominant parameters, together with experimental measurement on a current graphite-aluminum composite. The statistical strength of several graphite spools are measured by testing single filament specimens at the beginning and at the end of the spools, thereby characterizing the statistical parameters associated with the aluminum wire, produced from continuous liquid infiltration process are tested in tension. The metal matrix composite statistical strengths from different spools are compared with the respective statistical strength of the parent fiber. The results suggest that, given proper interpretation, single filament fiber strength is a sensitive parameter for quality assurance of metal matrix composites.


N89-26927# Illinois Univ., Urbana. Dept. of Chemistry.
Report, 1 Oct. 1985 - 31 Oct. 1988
Jiri Jonas 17 Feb. 1989
(Grant AF-AFOSR-0345-85; AF Proj. 2303)
(AD-A205292; AFOSR-89-0263TR) Avail: NTIS HC A03/MF
A01 CSCL 07/2

The NMR and Raman techniques were used to investigate the hydrolysis and condensation mechanism in B203-SiO2; A1203-SiO2; and Na2O-A1203-SiO2 systems. The solid state NMR techniques were employed together with BET methods to follow the thermal treatment of the gels. In addition to the NMR and Raman techniques, the SANS method was employed to study the effects of fluoride anion catalyst on the sol-gel process involving TMOS. High pressure NMR studies of the dynamic structure of the highly viscous liquids focused on three projects: (1) The self-diffusion behavior, and the applicability of hydrodynamic equations at the molecular level for a model lubricant 2-ethylhexylbenzoate; (2) the effect of the dipole moment on the hydrodynamic behavior of highly polar fluids; and (3) the effect of molecular flexibility on the relationship between molecular properties and shear viscosity at extreme conditions of pressure.




Includes chemical analysis, e.g., chromatography; combustion theory; electrochemistry; and photochemistry.

For related information see also 77 Thermodynamics and Statistical Physics..

N89-26928# National Inst. of Standards and Technology,
Gaithersburg, MD. Surface Science Div.
C. J. Powell, ed. Jan. 1989 142 p
(PB89-161889; NISTIR-89/4025) Avail: NTIS HC A07/MF A01

Technical activities of the NIST Surface Science Division during Fiscal Years 1987 and 1988 are summarized. These activities include surface-standards work, experimental and theoretical research in surface science, the development of improved measurement methods, and applications to important scientific and national problems. A listing is given of publications, talks, professional committee participation, and professional interactions by the Division staff.


N89-26926# Lawrence Livermore National Lab., CA.
H. D. Beeson, R. D. McClenagan, F. J. Benz, W. J. Pitz, C. K.
Westbrook, and J. H. S. Lee (McGill Univ., Montreal, Quebec )

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