Bending-torsional flutter of a swept wing in a highdensity, low-speed flow.
Bending-torsional flutter of uniform swept wing with velocity component aerodynamic-strip theory
OSCILLATING WING↗
SEARCH · Engineering Papers
Results for “vibrational analysis”
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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Stability of a bar under eccentric follower force.
Uniform cantilevered bar subject to eccentric compressive follower force, considering warping rigidity, bending-torsional flutter and stability
ELASTIC BAR↗
Preliminary analysis of the effects of pressure space correlations on the vibrations of Apollo flight structure
Vibration response of Apollo skin structure to convected boundary layer turbulence
Crocker, M. J.↗
Dynamic behavior of the spherical squeeze-film hybrid bearing.
Asymptotic analysis for stability and vibration response of spherical squeeze-film hybrid bearing, obtaining perturbation solutions
Chiang, T.↗
Improved fluid dynamics similarity, analysis and verification. Part 3 - Two-phase flow in vibrating discharge lines Final report, 29 Jun. 1965 - 28 Jun. 1968
Two phase flow in discharge line with edged entrance under vibratory and nonvibratory conditions
Griebe, R. W.↗
On the use of Morse eigenfunctions for the variational calculation of bound states of diatomic molecules
Morse eigenfunctions for variational calculation of diatomic molecules vibrational-rotational energy level analysis, showing better convergence than harmonic oscillator basis
Dickinson, A. S.↗
Efficiencies in the exchange of translational and vibrational energies in cyclopropane-argon mixtures
Cyclopropane-argon mixtures translational and vibrational energies exchange efficiencies analysis based on intermolecular potential
Taylor, J. E.↗
Analysis of spectra of acoustical signals at the outlet of a nonlinear system under the action of the sum of the harmonic sources
The establishment of specific relations between components of the spectra at the outlet of a nonlinear system are discussed for simplifying the analysis of noise and vibration for an internal combustion engine.
Sverkunov, Y. D.↗
Guide to a condensed form of NASTRAN
A limited capability form of NASTRAN level 16 is presented to meet the needs of universities and small consulting firms. The input cards, the programming language of the direct matrix abstraction program, the plotting, the problem definition, and the modules' diagnostic messages are described. Sample problems relating to the analysis of linear static, vibration, and buckling are included. This guide can serve as a handbook for instructional courses in the use of NASTRAN or for users who need only the capability provided by the condensed form.
Rogers, J. L., Jr.↗
On the analytical modeling of the nonlinear vibrations of pretensioned space structures
Pretensioned structures are receiving considerable attention as candidate large space structures. A typical example is a hoop-column antenna. The large number of preloaded members requires efficient analytical methods for concept validation and design. Validation through analyses is especially important since ground testing may be limited due to gravity effects and structural size. The present investigation has the objective to present an examination of the analytical modeling of pretensioned members undergoing nonlinear vibrations. Two approximate nonlinear analysis are developed to model general structural arrangements which include beam-columns and pretensioned cables attached to a common nucleus, such as may occur at a joint of a pretensioned structure. Attention is given to structures undergoing nonlinear steady-state oscillations due to sinusoidal excitation forces. Three analyses, linear, quasi-linear, and nonlinear are conducted and applied to study the response of a relatively simple cable stiffened structure.
Housner, J. M.↗
Experimental determination of gap flow-conditioned forces at turbine stages and their effect on the running stability of simple rotors
Instabilities in turbine operation can be caused by forces which are produced in connection with motions involving the oil film in the bearings. An experimental investigation regarding the characteristics of such forces in the case of three typical steam turbine stages is conducted, taking into account the effect of various parameters. Supplementary kinetic tests are carried out to obtain an estimate of the flow forces which are proportional to the velocity. The measurements are based on the theoretical study of the damping characteristics of a vibrational model. A computational analysis of the effect of the measured fluid forces on the stability characteristics of simple rotor model is also conducted.
Wohlrab, R.↗
Analysis of the surface load and radiated sound of a vibrating airfoil with application to the experiment of Brooks
A method is developed for calculating the surface load and radiated sound from a vibrating surface in a compressible viscous fluid. The method is applied to a thin two-dimensional elliptic cross-section. For large values of the viscous diffusion parameter, the surface load tends to an elliptic distribution in agreement with the results of inviscid theory when edge pressure continuity is enforced. For thin surfaces, the surface load is insensitive to variations in the thickness ratio. A three-dimensional spectral technique is developed to calculate the inviscid surface load and radiated sound from a thin vibrating airfoil. The inviscid theory predicts the correct form of the far field sound pressure and its phase. The actual levels are somewhat sensitive to the choice of theoretical spanwise surface pressure mode but are in better agreement with the experiment than the surface pressure. The comparison of theoretical and experimental surface pressure indicates that the viscous theory, used to validate the inviscid theory, is either inadequate or there is a source of experimental error.
Yates, J. E.↗
Proceedings of the Workshop on Identification and Control of Flexible Space Structures, Volume 2
The results of a workshop on identification and control of flexible space structures held in San Diego, CA, July 4 to 6, 1984 are discussed. The main objectives of the workshop were to provide a forum to exchange ideas in exploring the most advanced modeling, estimation, identification and control methodologies to flexible space structures. The workshop responded to the rapidly growing interest within NASA in large space systems (space station, platforms, antennas, flight experiments) currently under design. Dynamic structural analysis, control theory, structural vibration and stability, and distributed parameter systems are discussed.
Rodriguez, G.↗
On dynamics of laminated anisotropic plates using a refined mixed plate element
An analysis of the free vibration and transient response of laminates using a mixed shear flexible element is presented. The element is based on a refined theory that accounts for a parabolic distribution of the transverse shear stresses through each lamina and requires no shear correction coefficients. The mixed formulation of the theory treats the five displacement functions and six stress resultants independently so that they are nodal degrees of freedom in the finite element model. Sample problems using the element are analyzed and the results of free vibration and transient response are presented. Compared to the existing shear deformation plate theory the present refined theory gives more accurate results for frequencies, displacements and stresses.
Putcha, N. S.↗
Space shuttle main engine vibration data base
The Space Shuttle Main Engine Vibration Data Base is described. Included is a detailed description of the data base components, the data acquisition process, the more sophisticated software routines, and the future data acquisition methods. Several figures and plots are provided to illustrate the various output formats accessible to the user. The numerous vibration data recall and analysis capabilities available through automated data base techniques are revealed.
Lewallen, Pat↗
Sensitivity analysis for large-scale problems
The development of efficient techniques for calculating sensitivity derivatives is studied. The objective is to present a computational procedure for calculating sensitivity derivatives as part of performing structural reanalysis for large-scale problems. The scope is limited to framed type structures. Both linear static analysis and free-vibration eigenvalue problems are considered.
Noor, Ahmed K.↗
Transonic Aeroelasticity Analysis For Helicopter Rotor Blade
Numerical-simulation method for aeroelasticity analysis of helicopter rotor blade combines established techniques for analysis of aerodynamics and vibrations of blade. Application of method clearly shows elasticity of blade modifies flow and, consequently, aerodynamic loads on blade.
Chang, I-Chung↗
Structural verification of an aged composite reflector
A structural verification program applied to qualifying two heritage composite antenna reflectors for flight on the TOPEX satellite is outlined. The verification requirements and an integrated analyses/test approach employed to meet these requirements are described. Structural analysis results and qualification vibration test data are presented and discussed. It was determined that degradation of the composite and bonding materials caused by long-term exposure to an uncontrolled environment had not severely impaired the integrity of the reflector structures. The reflectors were assessed to be structurally adequate for the intended TOPEX application.
Lou, Michael C.↗