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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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Unreinforced circular cutouts effects on buckling behavior of circular cylindrical shells under axial compression, using photoelastic plastic shells
Vibration characteristics of circular cylindrical shells containing water under axial excitation, investigating bubble formation and shell-fluid interaction
Linear thin shell theory in complex dependent variable form for determining fourth order partial differential equations, considering elastic shells with edge loads
Circular cylindrical photoelastic shells buckling modes under axial compression using high speed isoclinic photography, discussing shallow shell equations applicability to early stages
Finite element method analysis of axisymmetrically loaded thin shells of revolution, considering nonlinearity due to material properties and shell geometry changes
Reticulated shell structure buckling using approximate equivalent shell and discrete analysis of individual beams
Thin walled shells structural vibration, buckling and stress analysis by computer methods, discussing shell theory and design
Computer program solves vibration modes and frequencies of thin shells of revolution having general meridional curvature and orthotropic elastic properties in order to evaluate the dynamic behavior of structures with thin shelled components.
Shell impact response and wave propagation in cylindrical and conical shells by experimental and analytical methods
Thin shell isotropic clamped free elliptical cylindrical shells with various cross sectional eccentricities, measuring frequencies and mode shapes by vibration analysis
Prestressed thin shells elastic deformation, using Kirchhoff hypothesis of shell theory
Computer program on axisymmetric response of shells with other meridional geometries and response of shells subjected to asymmetric loads is described. Description of theory, method of solution, instructions for preparing input data, and two sample problems to illustrate data preparation and output format are included.
The activated diffusion brazing process was developed for attaching TD-NiCr and U700 finned airfoil shells to matching Rene 80 struts obstructing the finned cooling passageways. Creep forming the finned shells to struts in combination with precise preplacement of brazing alloy resulted in consistently sound joints, free of cooling passageway clogging. Extensive tensile and stress rupture testing of several joint orientation at several temperatures provided a critical assessment of joint integrity of both material combinations. Trial blades of each material combination were fabricated followed by destructive metallographic examination which verified high joint integrity.
The modified structure method, which is based on Koiter's theory of imperfections, was used to calculate approximate buckling loads of several shells of revolution. The method does not appear to be practical for shells because, in many cases, the prebuckling nonlinearity may be too large to be treated accurately as a small imperfection.
A large deflection elastic-plastic analysis is presented, applicable to orthotropic axisymmetric plates and shells of revolution subjected to monotonic and cyclic loading conditions. The analysis is based on the finite-element method. It employs a new higher order, fully compatible, doubly curved orthotropic shell-of-revolution element using cubic Hermitian expansions for both meridional and normal displacements. Both perfectly plastic and strain hardening behavior are considered. Strain hardening is incorporated through use of the Prager-Ziegler kinematic hardening theory, which predicts an ideal Bauschinger effect. Numerous sample problems involving monotonic and cyclic loading conditions are analyzed. The monotonic results are compared with other theoretical solutions.
Drift shells of trapped particles starting from a single field line in the earth's magnetic field may become separated owing to an electric field. By using the formalism of the shell-splitting function, this separation is calculated for an arbitrary curl-free time-independent electric field satisfying E.B = 0, with no limitation on the particle's longitudinal excursion. The effect of nondipole field components is also taken into account to the lowest order.
The transient response due to longitudinal impact of three aluminum cylindrical shells of different thickness-to-radius ratios is studied both analytically and experimentally. The analyses were obtained from method of characteristics' solutions of two sets of equations: one which includes the transverse shear, radial inertia, and rotary inertial effects; and the other set is from a modified membrane theory. Experimentally, longitudinal and circumferential strains are monitored along the length of each of the shells; the velocity of the impacter ring is also measured. The experimental results of this study indicate that the wave front, after traveling three diameters from the impacted end, propagates at essentially the plate velocity, in agreement with the theory. In addition, the longitudinal and circumferential strain calculated from the two theories are in good agreement with the experimental results.
This paper examines some basic considerations underlying dynamic shell response analysis and the impact of these considerations upon the practical aspects of solution by numerical methods. Emphasis is placed on the solution of linear problems. The present states of development of the finite difference and finite element methods are reviewed, and techniques for the treatment of temporal variation are discussed. An examination is made of the frequency parameters characteristic of thin shell theory, applied excitations, and spatial mesh geometries, and the significance of these parameters with respect to computational convergence is illustrated.