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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Noise Transmission Loss of a Rectangular Plate in an Infinite Baffle

An improved analytical procedure was developed that allows for the efficient calculation of the noise transmission characteristics of a finite rectangular plate. Both isotropic and symmetrically laminated composite plates are considered. The plate is modeled with classic thin-plate theory and is assumed to be simply supported on all four sides. The incident acoustic pressure is assumed to be a plane wave impinging on the plate at an arbitrary angle. The reradiated pressure is assumed to be negligible compared with the blocked pressure, and the plate vibrations are calculated by a normal-mode approach. A Green's function integral equation is used to link the plate vibrations to be transmitted far-field sound waves, and transmission loss is calculated from the ratio of incident to transmitted acoustic powers. The result is a versatile research and engineering analysis tool that predicts noise transmission loss and enables the determination of the modal behavior of the plate.

Roussos, Louis A.↗
NASA NTRS1990

Vibrations of rectangular plates with moderately large initial deflections at elevated temperatures using finite element method

A finite-element formulation is developed for the free vibration of rectangular plates which are under the influence of moderately large stress-free initial deflections and large thermal deflections. The von Karman nonlinear strain-displacement relations are used to account for the thermal deflections. The plates are thin, isotropic, and Hookean in nature. The temperature imposed on the plate is assumed to be constant through the thickness of the plate. Uniform and sinusoidal temperature distributions are studied. The material properties of the plates are temperature-dependent due to the relatively high temperatures imposed on the plates.

Gray, C. C.↗
NASA NTRS1959

Loads and Deformations of Buckled Rectangular Plates

The nonlinear large-deflection equations of von Karman for plates are converted into a set of linear equations by expanding the displacements Into a power series in terms of an arbitrary parameter. The postbuckling behavior of simply supported rectangular plates subjected to longitudinal compression and subject to a uniform temperature rise is investigated in detail by solving the first few of the equations. Experimental data are presented for the compression problem. Comparisons are made for total shortening and local strains and deflections which indicate good agreement between experimental and theoretical results.

Stein, Manuel↗
NASA NTRS1942

Critical Compressive Stress for Flat Rectangular Plates Supported Along All Edges and Elastically Restrained Against Rotation along the Unloaded Edges

A chart is presented for the values of the coefficient in the formula for the critical compressive stress at which buckling may be expected to occur in flat rectangular plates supported along all edges and, in addition, elastically restrained against rotation along the unloaded edges. The mathematical derivations of the formulas required in the construction of the chart are given.

Lundquist, Eugene E↗
NASA NTRS1941

Critical Compressive Stress for Flat Rectangular Plates Supported Along all Edges and Elastically Restrained Against Rotation Along the Unloaded Edges, Special Report 189

A chart is presented for the values of the coefficient in the formula for the critical compressive stress at which buckling may be expected to occur in flat rectangular plates supported along all edges and, in addition, elastically restrained against rotation along the unloaded edges. The mathematical derivations of the formulas required in the construction of the chart are given.

Lundquist, Eugene E.↗
NASA NTRS1987

Buckling Analysis of Rectangular Plates With Holes

BUCKO is computer program developed to predict buckling of rectangular compression-loaded orthotropic plate with centrally located cutout. Plate assumed balanced, symmetric laminate of uniform thickness. Cutout shape elliptical, circular, rectangular, or square. Package includes sample data demonstrating essence of program and ease of use. Written in FORTRAN V.

Nemeth, M. P.↗
NASA NTRS1948

Compressive buckling of flat rectangular plates supported by rigid posts

Results of a theoretical investigation of the compressive buckling of flat, rectangular, simply supported plates supported in the interior by equally spaced rows of rigid posts are presented. It is found that the plates buckle as if simply supported along all of the transverse lines or else all of the longitudinal lines passing through the rigid posts, the occurrence of the one buckling mode or the other depending on the number and spacing of the posts.

LOADS AND STRESSES, STRUCTURAL - COMPRESSION↗
NASA NTRS1993

View factors for perpendicular and parallel rectangular plates

Simplified expressions (in comparison to currently used expressions, such as one developed by Howell, 1982) are developed for computing the view factors for rectangular perpendicular and parallel plates in the analysis of radiant exchanges between surfaces separated by a radiatively transparent medium. It is shown that the reported expressions for rectangular perpendicular and parallel plates with varying position and size having parallel boundaries satisfy the properties of the view factors.

Ehlert, J. R.↗
NASA NTRS1984

A finite element method for nonlinear forced vibrations of rectangular plates

The finite element method has been extended to determine the response of large amplitude forced vibrations of thin plates. A harmonic force matrix of a rectangular element under uniform harmonic excitation is developed for nonlinear forced vibration analysis. Inplane deformation and inertia are both considered in the formulation. Results obtained are compared with simple elliptic response, perturbation and other approximation solutions.

Mei, C.↗
NASA NTRS1992

Initial postbuckling response of anisotropic laminated rectangular plates

It has been shown that anisotropic plates can have unstable postbuckling behavior resulting in potential imperfection sensitivity. The present paper quantifies the degree of instability for rectangular, simply supported asymmetrically laminated plates. The analysis is based on asymptotic Koiter-type expansion of postbuckling response. The degree of postbuckling instability is quantified in terms of the reduction in load carrying capacity in the immediate postbuckling range. For graphite-epoxy plates it is found that this measure of instability is very small unless the lamination asymmetry is very pronounced.

Johnson, Eric R.↗
NASA NTRS1990

Initial postbuckling response of an unsymmetrically laminated rectangular plate

It was shown that anisotropic plates can have unstable postbuckling behavior resulting in potential imperfection sensitivity. The degree of instability for rectangular, simply-supported, cross-ply laminated plates is quantified. The analysis is based on asymptotic Koiter-type expansion of postbuckling response. The degree of postbuckling instability is quantified in terms of the reduction in load carrying capacity in the immediate postbuckling range. For graphite-epoxy plates it is found that this measure of instability is very small. Only a low aspect ratio plate with a high degree of anisotropy can have any significant reduction in its buckling load.

Haftka, Raphael T.↗