WorldCat Identities

United States Army Aviation Systems Command

Overview
Works: 302 works in 366 publications in 1 language and 13,440 library holdings
Genres: History 
Classifications: DS79.744.L64, 956.7044
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A data acquisition and control program for axial-torsional fatigue testing by Sreeramesh Kalluri ( )
2 editions published in 1989 in English and held by 142 WorldCat member libraries worldwide
A computer program was developed for data acquisition and control of axial -torsional fatigue experiments. The mult-tasked, interrupt-driven program is capable of dual-channel control and six-channel data acquisition. It can be utilized to perform inphase and out-of-phase axial-torsional isothermal fatigue or deformation experiments. The program was successfully used to conduct inphase axial torsional fatigue experiments on 304 stainless steel at room temperature and on Hastelloy X 800 C. This paper describes the details of the software and gives some of the results generated to date. Failure of engineering components due to fatigue is a common occurrence in the aerospace and automotive industries. It is therefore necessary to characterize the fatigue behavior of materials so that the engineering components can be operated safely and reliably
Determination of depth-viewing volumes for stereo three-dimensional graphic displays by Russell V Parrish ( Book )
3 editions published in 1990 in English and held by 138 WorldCat member libraries worldwide
Three-dimensional (real-world) pictorial displays incorporating true depth cures via stereopsis techniques offer a potential means of displaying complex information in a natural way to prevent loss of situational awareness and provide increases in pilot/vehicle performance in advanced flight display concepts. Optimal use of stereopsis cueing requires an understanding of the depth-viewing volume available to the display designer. This report presents suggested guidelines for the depth-viewing volume from a empirical determination of the effective region of the stereopsis cueing (at several distances between the viewer and the cathode ray tube (CRT) screen) for a time-multiplexed stereopsis display system. The results provide the display designer with information that will allow more effective placement of depth information to enable the full exploitation of stereopsis cueing. Additionally, the data revealed the fact that increasing the viewer-CRT screen distances provides increasing amount of usable depth but decreases the field of view. A stereopsis hardware system that permits an increased viewer-screen distance by incorporating larger screen sizes or collimation optics to maintain the field of view at required levels would provide a much larger stereo depth-viewing volume
Behavior of composite/metal aircraft structural elements and components under crash type loads what are they telling us? by Huey D Carden ( Book )
1 edition published in 1990 in English and held by 133 WorldCat member libraries worldwide
Failure behavior results are presented from crash dynamics research using concepts of aircraft elements and substructure not necessarily designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs which incorporate improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures which include individual fuselage frames, skeleton subfloors with stringers and floor beams but without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models. It is believed that the similarity in behavior is giving the designer and dynamists much information about what to expect in the crash behavior of these structures and can guide designs for improving the energy absorption and crash behavior of such structures
Stereopsis cueing effects on hover-in-turbulence performance in a simulated rotorcraft by Russell V Parrish ( Book )
3 editions published in 1990 in English and held by 132 WorldCat member libraries worldwide
The efficacy of stereopsis cueing in pictorial displays was assessed in a real-time piloted simulation of a rotorcraft precision 'hover-in- turbulence' task. Seven pilots endeavored to maintain a hover by visually aligning a set of inner and outer wickets (major elements of a real-world pictorial display) to attain the desired hover position. A full factorial experimental design was used. The display conditions examined included the presence or absence of a velocity display element (a velocity head-up display) as well as the stereopsis cueing conditions, which included nonstereo (binoptic or monoscopic, i.e., no depth cues other than those provided by a perspective, real-world display), three-dimensional stereo, and 'hyperstereo' (telestereopsis). Subjective and objective results indicate that the depth cues provided by the stereo displays enhanced the situational awareness of the pilot and enabled improved hover performance being achieved with the combined use of stereo and the velocity display element. Pilot control input data revealed that less control action was required to attain the improved hover performance with the stereo displays. Keywords: Stereoscopic display; Man machine system; Pictorial display; Cues stimuli; Piloted flight simulation; Hovering. (edc)
A basis for solid modeling of gear teeth with application in design and manufacture ( Book )
1 edition published in 1992 in English and held by 130 WorldCat member libraries worldwide
An incremental strategy for calculating consistent discrete CFD sensitivity derivatives ( Book )
1 edition published in 1992 in English and held by 129 WorldCat member libraries worldwide
In this preliminary study involving advanced CFD codes, an incremental formulation, also known as the delta or 'correction' form, is presented for solving the very large sparse systems of linear equations which are associated with aerodynamic sensitivity analysis. For typical problems in 2D, a direct solution method can be applied to these linear equations in either the standard or the incremental form, in which case the two are equivalent. Rerative methods appear to be needed for future 3D applications, however, where direct solver methods require much more computer memory than is currently available. Iterative methods for solving these equations in the standard form result in certain difficulties, such as ill-conditioning of the coefficient matrices, which can be overcome when these equations are cast in the incremental form; these and other benefits are discussed herein. The methodology is successfully implemented and tested in 2D using an upwind, cell-centered, finite volume formulation applied to the thin-layer Navier-Stokes equations. Results are presented for two laminar sample problems: (1) transonic flow through a double-throat nozzle, and (2) flow over an isolated airfoil
Mechanical property characterization and impact resistance of selected graphite/PEEK composite materials by Donald J Baker ( Book )
1 edition published in 1991 in English and held by 129 WorldCat member libraries worldwide
Computerized inspection of gear tooth surfaces ( Book )
1 edition published in 1989 in English and held by 128 WorldCat member libraries worldwide
Determination of real machine-tool settings and minimization of real surface deviation by computerized inspection by F. L Litvin ( Book )
1 edition published in 1991 in English and held by 128 WorldCat member libraries worldwide
A numerical method is developed for the minimization of deviations of real tooth surfaces from the theoretical ones. The deviations are caused by errors of manufacturing, errors of installment of machine-tool settings and distortion of surfaces by heat-treatment. The deviations are determined by coordinate measurements of gear tooth surfaces. The minimization of deviations is based on the proper correction of initially applied machine-tool settings. The contents of accomplished research project cover the following topics: (1) Description of the principle of coordinate measurements of gear tooth surfaces; (2) Derivation of theoretical tooth surfaces (with examples of surfaces of hypoid gears and references for spiral bevel gears); (3) Determination of the reference point and the grid; (4) Determination of deviations of real tooth surfaces at the points of the grid; and (5) Determination of required corrections of machine-tool settings for minimization of deviations
Observations on computational methodologies for use in large-scale, gradient-based, multidisciplinary design incorporating advanced CFD codes ( Book )
1 edition published in 1992 in English and held by 124 WorldCat member libraries worldwide
This paper briefly outlines how a combination of various computational methodologies could reduce the enormous computational costs envisioned in using advanced CFD codes in gradient-based optimized multidisciplinary design (MdD) procedures. Implications of these MdD requirements upon advanced CFD codes are somewhat different than those imposed by a 'single' discipline design. A means for satisfying these MdD requirements for gradient information is presented which appears to permit: first, some leeway in the CFD solution algorithms which can be used; second, an extension to 3-D problems; and third, straightforward use of other computational methodologies. Many of these observations have previously been discussed as possibilities for doing parts of the problem more efficiently; the contribution here is observing how they fit together in a mutually beneficial way
Computer code for predicting coolant flow and heat transfer in turbomachinery by Peter L Meitner ( Book )
1 edition published in 1990 in English and held by 123 WorldCat member libraries worldwide
Influence of linear profile modification and loading conditions on the dynamic tooth load and stress of high contact ration gears ( Book )
1 edition published in 1990 in English and held by 121 WorldCat member libraries worldwide
This paper presents a computer simulation for the dynamic response of high-contact-ratio spur gear transmissions. High contact-ratio spur gear transmissions. High contact ratio gears have the potential to produce lower dynamic tooth loads and minimum root stress but they can be sensitive to tooth profile errors. The analysis presented in this paper examines various profile modifications under realistic loading conditions. The effect of these modifications on the dynamic load (force) between mating gear teeth and the dynamic root stress is presented. Since the contact stress is dependent on the dynamic load, minimizing dynamic loads will also minimize contact stresses. This paper shows that the combination of profile modification and the applied load (torque) carried by a gear system has a significant influence on gear dynamics. The ideal modification at one value of applied load will not be the best solution for a different load. High-contact-ratio gears were found to require less modification than standard low-contact-ratio gears
Differential equation based method for accurate approximations in optimization by Jocelyn I Pritchard ( Book )
1 edition published in 1990 in English and held by 121 WorldCat member libraries worldwide
Computer simulation of gear tooth manufacturing processes by Dimitri Mavriplis ( Book )
1 edition published in 1990 in English and held by 120 WorldCat member libraries worldwide
This report discusses the use of computer graphics to simulate gear tooth manufacturing procedures. An analytical basis for the simulation is established for spur gears. The simulation itself, however, is developed not only for spur gears, but for straight bevel gears as well. The applications of the developed procedure extend from the development of finite elements models of heretofore intractable geometrical forms, to exploring the fabrication of nonstandard tooth forms. (kr)
NACA 0015 wing pressure and trailing vortex measurements by K. W MacAlister ( Book )
1 edition published in 1991 in English and held by 120 WorldCat member libraries worldwide
A NACA 0015 semispan wing was placed in a low-speed wind tunnel, and measurements were made of the pressure on the upper and lower surface of the wing and of the velocity across the vortex trailing downstream from the tip of the wing. Pressure data were obtained for both 2D and 3D configurations. These data feature a detailed comparison between wing tips with square and round lateral edges. A two-component laser velocimeter was used to measure velocity profiles across the vortex at numerous stations behind the wing and for various combinations of conditions. These conditions include three aspect ratios, three chord lengths, a square- and a round-lateral tip, presence or absence of a boundary-layer trip, and three image plane positions located opposite the wing tip. Both pressure and velocity measurements were made for angles of attack of 4 deg less then or equal to alpha less then or equal to 12 deg and for Reynolds. numbers of 1 x 10 deg less then or equal to Re less then or equal to 3 x 10 deg. The addition of a round-lateral edge to the wing Up was found to eliminate the secondary vortex near the wing Up, but had little effect on the downs characteristics of the trailing vortex. The increase in wing lift near the Lip because of the presence of the trailing vortex was evident in the surface pressure, but was not captured by circulation-box measurements. The circumferential velocity within the vortex was found to reach free-stream values and produce core rotational speeds as high as 44,000 rpm. The streamwise velocity within the viscous wake that is shed from the wing was observed to form islands of peak velocity in the spiraling sheet that feeds into the trailing vortex
Combined effect of matrix cracking and stress-free edge on delamination by Satish A Salpekar ( Book )
1 edition published in 1990 in English and held by 120 WorldCat member libraries worldwide
Surface pitting fatigue life of noninvolute, low-contact-ratio gears by Dennis P Townsend ( Book )
1 edition published in 1990 in English and held by 120 WorldCat member libraries worldwide
Spur gear endurance tests were conducted to investigate the surface pitting fatigue life of nonivolute gears with low numbers of teeth and low contact ratios for use in advanced applications. The results were compared with those a standard involute design with a low number of teeth. The gear pitch diameter was 8.89 cm (3.50 in.) with 12 teeth on both gear designs. Test conditions were an oil inlet temperature of 320 K an oil outlet temperature of 350 K a maximum Hertz stress of 1.49 Gpa (216 ksi), and a speed of 10,000 rpm. The following results were obtained: The noninvolute gear had a surface pitting fatigue life approximately 1.6 times that of the standard involute gear of a similar design. The surface pitting fatigue life of the 3.43-pitch AISI 8620 noninvolute gear was approximately equal to the surface pitting fatigues the same load but at a considerably high maximum Hertz stress
Description of the U.S. Army small-scale 2-meter rotor test system by Arthur E Phelps ( Book )
1 edition published in 1987 in English and held by 119 WorldCat member libraries worldwide
A small scale powered rotor model was designed for use as a research tool in the exploratory testing of rotors and helicopter models. The model, which consists of a 29 hp rotor drive system, a four blade fully articulated rotor, and a fuselage, was designed to be simple to operate and maintain in wind tunnels of moderate size and complexity. Two six-component strain-gauge balances are used to provide independent measurement of the rotor and fuselage aerodynamic loads. Commercially available standardized hardware and equipment were used to the maximum extent possible, and specialized parts were design so that they could be fabricated by normal methods without using highly specialized tooling. The model was used in a hover test of three rotors having different planforms and in a forward flight investigation of a 21 percent scale model of a U.S. Army scout helicopter equipped with a mast mounted sight. Keywords: Rotor model; Hover testing; Rotor scaling
Topology of modified helical gears by F. L Litvin ( Book )
1 edition published in 1989 in English and held by 116 WorldCat member libraries worldwide
The topology of several types of modified surfaces of helical gears are proposed. The modified surfaces allow absorption of linear or almost linear function of transmission errors caused by gear misalignment, and improvement of the contact of gear tooth surfaces. Principles and corresponding programs for computer aided simulation of meshing and contact of gears have been developed. The results of this investigation are illustrated with numerical examples
A mathematical model of the UH-60 helicopter by Kathryn B Hilbert ( Book )
2 editions published in 1984 in English and held by 116 WorldCat member libraries worldwide
 
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Alternative Names

controlled identity U.S. Army Aviation and Troop Command

AVSCOM
United States. Army. Aviation Systems Command
US Army Aviation Systems Command
USAAVSCOM
Languages
English (54)