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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

IKOS: Sound Static Program Analysis

This is a tutorial on how to use the IKOS tool for static analysis of C/C++ code for flight critical system. The tutorial explains what static code analysis is, what kind of errors IKOS can find, and how to use the tool on single or multiple file projects. Simple examples are given to illustrate the use of the tool. This tutorial also describes the use of IKOS on real mission code, in this case, the flight software for the BioSentinel mission and the Troupe project in the Robust Software Engineering group.

Aviation↗
NASA NTRS1966

Mechanism continuously measures static and dynamic cable loads

Pulley mechanism measures the tensile loads on a cable under static and dynamic conditions, without disturbing the continuity of operation of the system. A set of takeoff pulleys are mounted on a pivoted frame that is linked to a strain gage which measures the frame displacement as a function of the static or dynamic tensile load on the cable.

Source record↗
NASA NTRS1968

Cryogenic seal concept for static and dynamic conditions

Seal rings reduce cryogenic pump seal leakage under static and dynamic conditions. The rings are fitted into annular diaphragms, which are affected by cryogenic pressure and temperature, to move against a mating ring, to increase seal-bearing loads under static conditions.

De Gaetano, E. A.↗
NASA NTRS1968

Static structural analysis of shell-type structures

Shell analysis manual provides methods for determining static deflections and internal load and stress distributions in shells under various loading conditions, and methods of analyzing static instability of shell structures. Also included are methods for determining the lightest shell wall for various constructions.

Baker, E. H.↗
NASA NTRS1968

Semiconductor ac static power switch

Semiconductor ac static power switch has long life and high reliability, contains no moving parts, and operates satisfactorily in severe environments, including high vibration and shock conditions. Due to their resistance to shock and vibration, static switches are used where accidental switching caused by mechanical vibration or shock cannot be tolerated.

Vrancik, J.↗
NASA NTRS1971

Static and Dynamic Analysis, F-14A Boron Horizontal Stabilizer

A static stress analysis and a dynamic modal analysis of the horizontal stabilizer of the F-14A aircraft has been conducted at the Naval Air Development Center employing the NASTRAN program. The structural model contains 1518 elements including bars, rods, shear panels and orthotropic and isotropic membrane elements with 1357 degrees of freedom. Static deflection and stresses, including thermal stresses, under maximum load at room and at elevated temperatures are calculated and results are in good agreement with experimental data. Through application of "Guyan Reduction" the number of degrees of freedom used in the dynamic analysis is reduced to 137 . The frequencies and mode shapes for the first two modes are obtained .

S. L. Huang↗
NASA NTRS1972

General chemical kinetics computer program for static and flow reactions, with application to combustion and shock-tube kinetics

A general chemical kinetics program is described for complex, homogeneous ideal-gas reactions in any chemical system. Its main features are flexibility and convenience in treating many different reaction conditions. The program solves numerically the differential equations describing complex reaction in either a static system or one-dimensional inviscid flow. Applications include ignition and combustion, shock wave reactions, and general reactions in a flowing or static system. An implicit numerical solution method is used which works efficiently for the extreme conditions of a very slow or a very fast reaction. The theory is described, and the computer program and users' manual are included.

Bittker, D. A.↗
NASA NTRS1972

A computer program for the geometrically nonlinear static and dynamic analysis of arbitrarily loaded shells of revolution, theory and users manual

A digital computer program known as SATANS (static and transient analysis, nonlinear, shells) for the geometrically nonlinear static and dynamic response of arbitrarily loaded shells of revolution is presented. Instructions for the preparation of the input data cards and other information necessary for the operation of the program are described in detail and two sample problems are included. The governing partial differential equations are based upon Sanders' nonlinear thin shell theory for the conditions of small strains and moderately small rotations. The governing equations are reduced to uncoupled sets of four linear, second order, partial differential equations in the meridional and time coordinates by expanding the dependent variables in a Fourier sine or cosine series in the circumferential coordinate and treating the nonlinear modal coupling terms as pseudo loads. The derivatives with respect to the meridional coordinate are approximated by central finite differences, and the displacement accelerations are approximated by the implicit Houbolt backward difference scheme with a constant time interval. The boundaries of the shell may be closed, free, fixed, or elastically restrained. The program is coded in the FORTRAN 4 language and is dimensioned to allow a maximum of 10 arbitrary Fourier harmonics and a maximum product of the total number of meridional stations and the total number of Fourier harmonics of 200. The program requires 155,000 bytes of core storage.

Ball, R. E.↗
NASA NTRS1972

Ballisistic range measurements of the drag and static and dynamic stability of a recoverable space shuttle booster vehicle

An experimental study has been conducted to determine the aerodynamic characteristics of a proposed recoverable space shuttle booster vehicle. Tests were made at Mach numbers of 0.7, 1.5, and 3.5 of two configurations, one with tail panels deflected 90 deg and one with tail panels deflected 70 deg. Both configurations were found to be highly statically stable at all Mach numbers. The dynamic behavior was erratic; the models exhibited both neutral dynamic stability and dynamic instability, and the motions experienced during free flight at the subsonic Mach number were very irregular. The flow field over the models was characterized by an extensive separated flow region which largely encompassed the tail panels. The experimental drag and static stability were not well predicted by available theoretical estimates.

Intrieri, P. F.↗
NASA NTRS1972

Aerodynamic and Acoustic Performance of Two Choked-Flow Inlets Under Static Conditions

Tests were conducted to determine the aerodynamic and acoustic performance of two choking flow inlets under static conditions. One inlet choked the flow in the cowl throat by an axial translation of the inlet centerbody. The other inlet employed a translating grid of airfoils to choke the flow. Both inlets were sized to fit a 13.97 cm diameter fan with a design weight flow of 2.49 kg/sec. The inlets were operated in both the choked and unchoked modes over a range of weight flows. Measurements were made of inlet pressure recovery, flow distortion, surface static pressure distribution, and fan noise suppression. Choking of the translating centerbody inlet reduced blade passing frequency noise by 29 db while yielding a total pressure recovery of 0.985. Noise reductions were also measured at 1/3-octave band center frequencies of 2500, 5000, and 20,000 cycles. The translating grid inlet gave a total pressure recovery of 0.968 when operating close to the choking weight flow. However, an intermittent high intensity noise source was encountered with this inlet that precluded an accurate measurement of inlet noise suppression.

Miller, B. A.↗
NASA NTRS1972

Comparison of NASTRAN and STARDYNE static analysis of a graphite fiber reinforced plastic truss structure

A static and buckling analysis of the ATS-F&G spacecraft reflector support truss (RST) and bridge truss assembly using NASTRAN was conducted. The RST is fabricated from a new material, graphite fiber reinforced plastic. A comparison is made with the NASTRAN results and the results of a similar analysis conducted using the stardyne program. The results of an actual static load test are also compared.

Honeycutt, G. H.↗
NASA NTRS1971

Static properties of hydrostatic thrust gas bearings with curved surfaces.

The classical treatment of circular, hydrostatic, orifice-regulated thrust gas bearings, in which perfectly plane bearing plates are assumed, is extended to include axisymmetric, but otherwise arbitrary, plate profiles. Plate curvature has a strong influence on bearing load capability, static stiffness, tilting stiffness, and side force per unit misalignment angle. By a suitable combination of gas inlet impedance and concave plate profile, the static stiffness can be made almost constant over a wide load range, and to remain positive at the closure load. Extensive measurements performed with convex and concave plates agree with theory to within the experimental error throughout and demonstrate the practical feasibility of using curved plates.

Rehsteiner, F. H.↗
NASA NTRS1972

Flyover and static tests to investigate external flow effect on jet noise from nonsuppressor and suppressor exhaust nozzles

The effect of external air flowing across exhaust nozzles on the jet noise characteristics of supersonic transport aircraft at high takeoff speeds was investigated. A series of flyover and static tests were conducted using an F-106B aircraft modified with two underwing nacelles each containing a calibrated J85-GE-13 turbojet engine. Comparison of flyover and static data indicated that external flow reduces the noise of an auxiliary inlet ejector nozzle. An unsuppressed plug nozzle was not affected while the plug suppressor configurations were not as effective in flight.

Burley, R. R.↗
NASA NTRS1972

Computer programs for estimation of STOL takeoff, landing, and static performance

A set of computer programs has been developed for evaluating the performance of powered-lift STOL aircraft. Included are a static performance summary and dynamic calculations of takeoff and landing performance. The input, output, options, and calculations for each program are described. The programs are written in FORTRAN IV and are currently available on TSS 360. Three independent sections are presented corresponding to the three programs: (1) static performance, (2) takeoff performance, and (3) landing performance.

Post, S. E.↗
NASA NTRS1973

Motor starting a Brayton cycle power conversion system using a static inverter

The power conversion module of a 2- to 15-kWe Brayton engine was motor started using a three-phase, 400-hertz static inverter as the power source. Motor-static tests were conducted for initial gas loop pressures of 10, 14, and 17 N/sq cm (15, 20, and 25 psia) over a range of initial turbine inlet temperatures from 366 to 550 K (200 to 530 F). The data are presented to show the effects of temperature and pressure on the motor-start characteristics of the rotating unit. Electrical characteristics during motoring are also discussed.

Curreri, J. S.↗
NASA NTRS1973

Static penetration resistance of soils

Model test results were used to define the failure mechanism associated with the static penetration resistance of cohesionless and low-cohesion soils. Knowledge of this mechanism has permitted the development of a new analytical method for calculating the ultimate penetration resistance which explicitly accounts for penetrometer base apex angle and roughness, soil friction angle, and the ratio of penetration depth to base width. Curves relating the bearing capacity factors to the soil friction angle are presented for failure in general shear. Strength parameters and penetrometer interaction properties of a fine sand were determined and used as the basis for prediction of the penetration resistance encountered by wedge, cone, and flat-ended penetrometers of different surface roughness using the proposed analytical method. Because of the close agreement between predicted values and values measured in laboratory tests, it appears possible to deduce in-situ soil strength parameters and their variation with depth from the results of static penetration tests.

Durgunoglu, H. T.↗
NASA NTRS1974

Preliminary static tests of a simulated upper-surface blown jet-flap configuration utilizing a full-size turbofan engine

The investigation was conducted to evaluate the static turning performance and the pressure and temperature environment of an upper-surface-blown wing and flap utilizing a small turbofan engine. The tests involved modifications of the engine primary nozzle designed to alleviate high temperature problems on the wing and flaps and yet provide acceptable static turning performance over the desired range of flap deflections and thrust conditions.

Shivers, J. P.↗