Nonsymmetric transverse vibrations of truncated conical shells technical report no. 3
Resonant frequencies and associated mode shapes of truncated conical shells over wide range of geometrical and modal parameters
CONICAL SHELL↗
SEARCH · Search NASA
Results for “nonsymmetric”
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.
Nonsymmetric transverse vibrations of truncated conical shells.
Resonant frequencies and mode shapes for transverse vibration of truncated conical shells obtained by considering effect of bending, membrane rigidity and inertia terms due to transverse motion
CONICAL SHELL↗
Symmetric and nonsymmetric buckling of finitely deformed eccentrically stiffened shells of revolution.
Finite difference method stability analysis of deformed eccentrically stiffened shells of revolution, accounting for finite prebuckling rotations
FINITE DIFFERENCE METHOD↗
Symmetric and nonsymmetric buckling of finitely deformed eccentrically stiffened shells of revolution.
Finite difference method stability analysis of deformed eccentrically stiffened shells of revolution, accounting for finite prebuckling rotations
FINITE DIFFERENCE METHOD↗
Inflatable shells - Nonsymmetric in-service loads.
Inflatable shell of revolution subject to asymmetric in-service loads noting field equations, mathematical model and numerical integration
Leonard, J. W.↗
Spin reorientation of a nonsymmetric body with energy dissipation
Stable rotating semi-rigid bodies were demonstrated analytically, and verified in flights such as Explorer 1 and ATS-5 satellites. The problem arises from the two potential orientations which the final spin vector can take after large angle reorientation from minor to major axis, i.e., along the positive or negative axis of the maximum inertia. Reorientation of a satellite initially spinning about the minor axis using an energy dissipation device may require that the final spin orientation be controlled. Examples of possible applications are the Apogee Motor Assembly with Paired Satellites (AMAPS) configuration, where proper orientation of the thruster is required; and reorientation of ATS-5, where the spin sensitive nature of the despin device (yo-yo mechanism) requires that the final spin vector point is a specified direction.
Cenker, R. J.↗
Effect of nonsymmetrical flow resistance upon orifice impedance resistance
A nonreactive orifice in an infinite baffle is analyzed. The pressure difference delta across the orifice varies sinusoidally with amplitude 1.0 and average value -P. The orifice resistance, delta p is discontinuous at zero velocity and exhibits the constant values R sub + and R sub - for u 0 and u 0, respectively. The resultant velocity has power in all harmonics of the excitation frequency. A quasi-linear resistance is defined and found to be relatively insensitive to the presence or absence of a resonant backing cavity; however, it does vary from 1.33 R sub + to 0.67 R sub + for a resistance ratio R sub +/R sub - between 0.5 and 2.0.
Posey, J. W.↗
Effect of nonsymmetrical flow resistance upon orifice impedance
Previous laboratory work has indicated that an orifice in a thin sheet behaves in a quasisteady manner under acoustical excitation. Also, it has been found that the steady flow resistance of an orifice may be dependent upon the direction of flow, especially in the presence of a crossflow on one side of the hole. An analytical study is presented which assumes a nonreactive orifice in an infinite baffle. The pressure difference across the orifice varies sinusoidally with amplitude 1.0 and average value -P. The orifice resistance is discontinuous at zero velocity and exhibits the constant values when the velocity is nonzero. The resultant velocity has power in all harmonics of the excitation frequency, providing an explanation of the even harmonic excitation observed by other investigators, but not predicted by symmetric nonlinearity. A quasilinear resistance is defined and found to be relatively insensitive to the presence or absence of a resonant backing cavity.
Posey, J. W.↗
Fractional-frequency rotor motion due to nonsymmetric clearance effects
Analysis based on the Jeffcott model is presented to explain 1/2 speed and 1/3 speed whirling motion occurring in rotors which are subject to periodic normal-loose or normal-tight radial stiffness variations. The normal-loose stiffness variation results due to bearing-clearance effects, while normal-tight stiffness variations result from rubbing over a portion of a rotor's orbit. The results demonstrate that 1/2 speed subharmonic motion can be explained as either a linear parametric-excitation phenomenon or as a stable nonlinear subharmonic motion. The 1/3 speed motion is shown to be possible due to the radial stiffness nonlinearity. A linear parametric-excitation analysis demonstrates that during a normal-tight rubbing condition, Coulomb damping significantly widens the potential range of unstable speeds.
Childs, D. W.↗
Magnetohydrodynamic equilibrium. III - Helically symmetric fields. IV - Nonequilibrium of nonsymmetric hydrodynamic topologies
It is pointed out that plasma confinement in stable equilibrium states constitutes a fundamental and still unresolved question in plasma astrophysics and thermonuclear fusion research. The problem has two parts related to the equilibrium states themselves and their mechanical stability. The question of the existence of general solutions of the field and fluid equations for the steady dynamical interaction of inviscid compressible fluids of high electrical conductivity with magnetic and gravity fields is considered. In the absence of fluid motions, the presented equations become the familiar equations of magnetostatics supplemented by an equation of state. Starting from this simplest case of magnetostatic equilibrium, the investigation proceeds to the more complex case of magnetohydrodynamic equilibrium. Examples of helically symmetric fields are presented to illustrate the use of the formulation for treating the dynamics of helically symmetric hydromagnetic flows.
Tsinganos, K. C.↗
Preliminary results in implementing a model of the world economy on the CYBER 205: A case of large sparse nonsymmetric linear equations
A brief description of the Model of the World Economy implemented at the Institute for Economic Analysis is presented, together with our experience in converting the software to vector code. For each time period, the model is reduced to a linear system of over 2000 variables. The matrix of coefficients has a bordered block diagonal structure, and we show how some of the matrix operations can be carried out on all diagonal blocks at once.
Szyld, D. B.↗
Numerical solution of large nonsymmetric eigenvalue problems
Several methods are discribed for combinations of Krylov subspace techniques, deflation procedures and preconditionings, for computing a small number of eigenvalues and eigenvectors or Schur vectors of large sparse matrices. The most effective techniques for solving realistic problems from applications are those methods based on some form of preconditioning and one of several Krylov subspace techniques, such as Arnoldi's method or Lanczos procedure. Two forms of preconditioning are considered: shift-and-invert and polynomial acceleration. The latter presents some advantages for parallel/vector processing but may be ineffective if eigenvalues inside the spectrum are sought. Some algorithmic details are provided that improve the reliability and effectiveness of these techniques.
Saad, Youcef↗
Fast secant methods for the iterative solution of large nonsymmetric linear systems
A family of secant methods based on general rank-1 updates was revisited in view of the construction of iterative solvers for large non-Hermitian linear systems. As it turns out, both Broyden's good and bad update techniques play a special role, but should be associated with two different line search principles. For Broyden's bad update technique, a minimum residual principle is natural, thus making it theoretically comparable with a series of well known algorithms like GMRES. Broyden's good update technique, however, is shown to be naturally linked with a minimum next correction principle, which asymptotically mimics a minimum error principle. The two minimization principles differ significantly for sufficiently large system dimension. Numerical experiments on discretized partial differential equations of convection diffusion type in 2-D with integral layers give a first impression of the possible power of the derived good Broyden variant.
Deuflhard, Peter↗
Stress, stability, and vibration of complex, branched shells of revolution.
A comprehensive computer program, designated BOSOR4, for analysis of the stress, stability, and vibration of segmented, ring-stiffened, branched shells of revolution and prismatic shells and panels is described. The program performs large-deflection axisymmetric stress analysis, small-deflection nonsymmetric stress analysis, modal vibration analysis with axisymmetric nonlinear prestress included, and buckling analysis with axisymmetric or nonsymmetric prestress. One of the main advantages of the code is the provision for realistic engineering details such as eccentric load paths, internal supports, arbitrary branching conditions, and a library of wall constructions. The program is based on the finite-difference energy method, which is very rapidly convergent with increasing numbers of mesh points.
Bushnell, D.↗
Stress, stability and vibration of complex, branched shells of revolution
A comprehensive computer program, designated BOSOR4, for analysis of the stress, stability, and vibration of segmented, ring-stiffened, branched shells of revolution and prismatic shells and panels is described. The program performs large-deflection axisymmetric stress analysis, small-deflection nonsymmetric stress analysis, modal vibration analysis with axisymmetric nonlinear prestress included, and buckling analysis with axisymmetric or nonsymmetric prestress. One of the main advantages of the code is the provision for realistic engineering details such as eccentric load paths, internal supports, arbitrary branching conditions, and a 'library' of wall constructions. The program is based on the finite-difference energy method, which is very rapidly convergent with increasing numbers of mesh points. The organization of the program is briefly described with the flow of calculations charted for each of the types of analysis. Overlay charts and core storage requirements are given for the CDC 6600, IBM 370/165, and UNIVAC 1108 versions of BOSOR4.
Bushnell, D.↗
Analytical displacements and vibrations of cantilevered unsymmetric fiber composite laminates
A fiber composite flat cantilever plate that has symmetric and nonsymmetric laminate configurations is theoretically investigated to determine its static and dynamic structural response. The finite element analysis method used includes a unique triangular finite element developed at Lewis for the analysis of fiber composite airfoils. The various responses investigated include tip displacements, natural frequencies, and fundamental mode shapes. The results show that the displacements and the natural frequencies can be in considerable error for nonsymmetric laminate configurations if the membrane-bending coupling is not taken into account. Structural response results obtained from ten laminate configurations are presented in tabular forms and may be used as an aid in selecting laminate configurations for composite airfoils.
Minich, M. D.↗
Non-symmetric two-stream instability
A theoretical investigation is performed concerning the instability spectrum of quasi-electrostatic waves at shifted half-odd-integer values of the cyclotron frequency due to nonsymmetric counterstreaming electron beams. The beam velocities parallel and perpendicular to the static magnetic field are represented by double Dirac delta functions with no imposition of parameter limitations. Systematic consideration is given to the coupling between plasma modes and cyclotron modes as well as the coupling between cyclotron modes of the two beams that result in shifted half-odd-integer multiples of the cyclotron frequency. The general dispersion equation for quasi-electrostatic waves is analyzed, and plasma-cyclotron coupling in the nonsymmetric case is treated by deriving approximate analytical expressions for maximum growth rates and marginal stability. Exact numerical solutions in both frequency and wavenumber space are obtained and compared with the analytical expressions. Cyclotron-cyclotron coupling modes are treated in the same way, and the results for both types of coupling are compared. It is found that certain modes may be weakened or completely suppressed when the Bessel functions for specific plasma parameters vanish.
Cuperman, S.↗
Statistical correlation analysis for comparing vibration data from test and analysis
A theory was developed to compare vibration modes obtained by NASTRAN analysis with those obtained experimentally. Because many more analytical modes can be obtained than experimental modes, the analytical set was treated as expansion functions for putting both sources in comparative form. The dimensional symmetry was developed for three general cases: nonsymmetric whole model compared with a nonsymmetric whole structural test, symmetric analytical portion compared with a symmetric experimental portion, and analytical symmetric portion with a whole experimental test. The theory was coded and a statistical correlation program was installed as a utility. The theory is established with small classical structures.
Butler, T. G.↗