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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1980

Sound transmission into a laminated composite cylindrical shell

In the context of the transmission of airborne noise into an aircraft fuselage, a mathematical model is presented for the transmission of an oblique plane sound wave into a laminated composite circular cylindrical shell. Numerical results are obtained for geometry typical of a narrow-bodied jet transport. Results indicate that from the viewpoint of noise attenuation on laminated composite shell does not appear to offer any significant advantage over an aluminum shell. However, the transmission loss of a laminated composite shell is sensitive to the orientation of the fibers and this suggests the possibility of using a laminated composite shell to tailor the noise attenuation characteristics to meet a specific need.

Koval, L. R.↗
NASA NTRS1962

Buckling of Orthotropic and Stiffened Conical Shells

Donnell type stability equations for thin circular orthotropic conical shells are presented and solved for external pressure, axial compression and combined loading. The solution is likewise applied to stiffened conical shells. Correlation with equivalent cylindrical shells yields a simple approximate stability analysis for orthotropic or ring-stiffened conical shells under hydrostatic pressure. The general instability of stiffened conical shells under hydrostatic pressure is also analysed by a more accurate approach. Preliminary experimental results for buckling of ring-stiffened conical shells under hydrostatic pressure are presented and discussed.

CONICAL SHELL↗
NASA NTRS1950

Small bending and stretching of sandwich-type shells

A theory has been developed for small bending and stretching of sandwich-type shells. This theory is an extension of the known theory of homogeneous thin elastic shells. It was found that two effects are important in the present problem, which are not normally of importance in the theory of curved shells: (1) the effect of transverse shear deformation and (2) the effect of transverse normal stress deformation. The first of these two effects has been known to be of importance in the theory of plates and beams. The second effect was found to occur in a manner which is typical for shells and has no counterpart in flat-plate theory. The general results of this report have been applied to the solution of problems concerning flat plates, circular rings, circular cylindrical shells, and spherical shells. In each case numerical examples have been given, illustrating the magnitude of the effects of transverse shear and normal stress deformation.

Reissner, Eric↗
NASA NTRS1938

Calculation of load distribution in stiffened cylindrical shells

Thin-walled shells with strong longitudinal and transverse stiffening (for example, stressed-skin fuselages and wings) may, under certain simplifying assumptions, be treated as static systems with finite redundancies. In this report the underlying basis for this method of treatment of the problem is presented and a computation procedure for stiffened cylindrical shells with curved sheet panels indicated. A detailed discussion of the force distribution due to applied concentrated forces is given, and the discussion illustrated by numerical examples which refer to an experimentally determined circular cylindrical shell.

Ebner, H↗
NASA NTRS1952

Stresses in a two-bay noncircular cylinder under transverse loads

A method, taking into account the effects of flexibility and based on a general eighth-order differential equation, is presented for finding the stresses in a two-bay, noncircular cylinder the cross section of which can be composed of circular arcs. Numerical examples are given for two cases of ring flexibility for a cylinder of doubly symmetrical (essentially elliptic) cross section, subjected to concentrated radial, moment, and tangential loads. The results paralleled those already obtained for shells with circular rings.

Griffith, George E↗
NASA NTRS1962

INSTABILITY ANALYSIS OF CYLINDRICAL SHELLS UNDER HYDROSTATIC PRESSURE

To determine the elastic buckling pressure of simply supported cylindrical shells subjected to lateral end axial hydrostatic forces, various versions of linear bending theories have been employed in the past. For certain shell dimensions, however the expressions commonly used may yield substantially differing results. In what follows, recent work on this problem by A. E. Armenakas and the writer is briefly reviewed. This work consisted primarily in employing a general bending theory of circular cylindrical shells under the influence of initial stress, developed earlier by the same authors, to re-examine the problem mentioned, and compare the results with those of previous investigations. The outcome was the establishment of a simple but accurate expression for the buckling pressure applicable to a wide range of shell dimensions.

CYLINDRICAL SHELL↗
NASA NTRS1994

Completed Beltrami-Michell Formulation for Analyzing Radially Symmetrical Bodies

A force method formulation, the completed Beltrami-Michell formulation (CBMF), has been developed for analyzing boundary value problems in elastic continua. The CBMF is obtained by augmenting the classical Beltrami-Michell formulation with novel boundary compatibility conditions. It can analyze general elastic continua with stress, displacement, or mixed boundary conditions. The CBMF alleviates the limitations of the classical formulation, which can solve stress boundary value problems only. In this report, the CBMF is specialized for plates and shells. All equations of the CBMF, including the boundary compatibility conditions, are derived from the variational formulation of the integrated force method (IFM). These equations are defined only in terms of stresses. Their solution for kinematically stable elastic continua provides stress fields without any reference to displacements. In addition, a stress function formulation for plates and shells is developed by augmenting the classical Airy's formulation with boundary compatibility conditions expressed in terms of the stress function. The versatility of the CBMF and the augmented stress function formulation is demonstrated through analytical solutions of several mixed boundary value problems. The example problems include a composite circular plate and a composite circular cylindrical shell under the simultaneous actions of mechanical and thermal loads.

Kaljevic, Igor↗
NASA NTRS1992

Design and analysis of filament-wound cylinders in compression

The objective of the study was to develop a more accurate model for the prediction of the compressive behavior of filament-wound composite cylindrical shells. Results from a closed-form analytical model and a three-dimensional finite element model show that the extensional and bending stiffness of the laminate is significantly reduced in tow cross-over regions and that bending-extension coupling is increased in comparison with classical lamination theory. The material properties predicted by a micromechanics analysis are included in a global finite element model of a filament-wound circular cylindrical shell which also incorporates variations in the laminate stacking thickness. Results from the global shell analysis are compared with experimental data.

Hipp, Patrick A.↗
NASA NTRS1981

Vibrations of cantilevered shallow cylindrical shells of rectangular planform

A cantilevered, shallow shell of circular cylindrical curvature and rectangular planform exhibits free vibration behavior which differs considerably from that of a cantilevered beam or of a flat plate. Some numerical results can be found for the problem in the previously published literature, mainly obtained by using various finite element methods. The present paper is the first definitive study of the problem, presenting accurate non-dimensional frequency parameters for wide ranges of aspect ratio, shallowness ratio and thickness ratio. The analysis is based upon shallow shell theory. Numerical results are obtained by using the Ritz method, with algebraic polynomial trial functions for the displacements. Convergence is investigated, with attention being given both to the number of terms taken for each co-ordinate direction and for each of the three components of displacement. Accuracy of the results is also established by comparison with finite element results for shallow shells and with other accurate flat plate solutions.

Leissa, A. W.↗
NASA NTRS1961

Research on Liquid Dynamics in Missile Fuel Tanks

This report presents the results of work completed during the period of 1 July 1961 through 30 September 1961 on the studies of vibrations of flexible tanks containing a liquid with a free surface. The coupling between free surface motion and tank bending is dis- cussed in some detail and preliminary experimental results are given which tend to collaborate the theoretical analysis. Experimental results for the effect of an internal fluid on the breathing frequencies of a circular cylindrical shell are also given. apparently new type of free surface sloshing motion induced by high frequency breathing vibrations is reported.

MISSILE↗
NASA NTRS1968

Buckling of thin-walled circular cylinders

This monograph indicates current practices for predicting buckling of uniform stiffened and unstiffened circular cylindrical shells under various types of static loading, and suggests the procedures that yield estimates of static buckling loads considered to be conservative. The buckling of truncated conical shells and shells of double curvature will be treated in separate monographs.

V. I. Weingarten↗