Showing papers on "Shell (structure) published in 1983"

Theory of Shell Structures

Abstract: Shell structures form key components in a very wide range of engineering enterprise. The theory of shell structures is an old and large subject, with a huge literature. However, this book is not a compilation of results from the past. Instead, it is an attempt to bring the essence of the subject within the grasp of engineers. It tackles the fundamental question of how bending and stretching effects combine and interact in shell structures from a physical point of view; and it shows that this approach leads to an understanding of the structural mechanics of shells in general, and to useful results in particular problems. The first half of the book is concerned mainly with the basic ideas and equations of equilibrium, geometry and elasticity, and their combination in various useful ways. In particular, it includes a simple treatment of the geometry of general curved surfaces. The second half of the book first investigates the behaviour of various practical shell structures under static loading. Then there are chapters on the buckling of shells, on vibration, and on the application of plastic theory to analysis and design.

Correction to: a thin viscous sheet model for continental deformation

Abstract: Summary. The governing equation derived by England & McKenzie for the deformation of a thin viscous shell contains an error. We give the correct derivation here and correct those figures where the change makes a visible difference. The correct results differ quantitatively from those of England & McKenzie but their conclusions are not affected.

Plasmon resonance broadening in small metal particles

Abstract: A quantum mechanical method based on the Kramers–Heisenberg dispersion relation is used to evaluate the dielectric response of small metal particles, and thereby to determine the influence of particle size on the widths of the plasmon resonance line shapes. Several different particle shapes are considered (sphere, cylinder, rectangular prism, spherical shell, and cylindrical shell) and for each shape a free electron Schrodinger equation is used to determine conduction band energies and dipole matrix elements. The main emphasis in this work is on particle sizes large enough that only the first order deviations from the infinite size limit are important, and for such sizes we find that the size dependent contribution to the width can be expressed in terms of an effective length Leff. This effective length is found to depend on the direction of the external field relative to the particle symmetry axes, and on the shape of the particle. For compact shapes, Leff is accurately approximated by 0.65 Lav along eac...

Anisotropic elasto-plastic finite element analysis of thick and thin plates and shells

Abstract: An elasto-plastic analysis of anisotropic plates and shells is undertaken by means of the finite element displacement method. A thick shell formulation accounting for shear deformation is considered, which is based on a degenerate three-dimensional continuum element. The accommodation of variable material properties, not only along the surface of the structure but also through the thickness, is made possible by a discrete layered approach. Although isoparametric elements of the Serendipity family give satisfactory solutions for thick and moderately thin shells the results exhibit ‘locking’ for an increasing ratio of span to thickness. To develop a numerical model which is applicable to thick or thin plates and shells, the nine-node Lagrangian element and the Heterosis element are also introduced into the present model. Plastic yielding is based on the Huber-Mises yield surface extended by Hill for anisotropic materials. The yield function is generalized by introducing anisotropic parameters of plasticity which are updated during the material strain hardening history. Numerical examples are presented and compared with available solutions. The effects of anisotropy on these solutions are also discussed.

Geometrically nonlinear formulation for the curved shell elements

Abstract: This paper presents a geometrically nonlinear formulation using total lagrangian approach for the three-dimensional curved shell elements. The basic element geometry is constructed using the coordinates of the middle surface nodes and the mid-surface nodal point normals. The element displacement field is described using three translations of the mid-surface nodes and the two rotations about the local axes. The existing shell element formulations are restricted to small nodal rotations between two successive load increments. The element formulation presented here removes such restrictions. This is accomplished by retaining nonlinear nodal rotation terms in the definition of the displacement field and the consistent derivation of the element properties. The formulation presented here is very general and yet can be made specific by selecting proper nonlinear functions representing the effects of nodal rotations. The element properties are derived and presented in detail. Numerical examples are also presented to demonstrate the behaviour and the accuracy of the elements.

Acetabulum sizer and drill guide

Abstract: An acetabulum sizer and drill guide for use in implanting an acetabular cup prosthesis comprises a substantially hemispherical shell having an outside surface that generally conforms to the outside surface of the prosthesis to be fitted into a prepared acetabulum. Viewing ports in the shell enable visual inspection of the acetabulum during sizing thereof. A circular peripheral rim on the shell is generally flush with the peripheral boundary of a properly sized acetabulum when the shell is seated therein. Drill guide structure on the shell functions to guide a drill bit into the pelvis bone adjacent the acetabulum in preparing the acetabulum for the acetabular cup prosthesis. A handle is releasably connected to the drill guide structure for manipulating the shell during sizing and drilling.

Casket and method of manufacture

Abstract: A casket and method for manufacture are disclosed according to which a shell or base, having outwardly flared walls, is constructed of corrugated fiberboard by a technique in which a planar sheet of corrugated fiberboard is cut to form a blank having interconnected portions corresponding to the areas of the flared side and end walls. A domed lid is also provided, being formed of corrugated fiberboard with a reinforcing marginal frame, provision being made for utilization of the lid either as a single unitary piece or as a split lid having two halves.

Cryogenic tank support system

Abstract: A single-stage cryogenic tank support system is disclosed having a large-radius support tube surrounding an internal storage tank, both of which are enclosed by an external shell. The attachment tube is secured to the internal storage tank and external shell by cold and hot support rings, respectively, in a manner that inhibits thermal conductivity, provides low bending stress to the system, and avoids resonant vibrations of the system at low frequencies.

Perforated cover assembly

Abstract: A perforated cover assembly is made of two oppositely dished shell members (1, 2)releasably interconnected at their peripheries to define a space (13) therebetween. The lower shell member (2) has a plurality of outlet perforations (12) spread over substantially its entire surface and each of which is raised relative to the immediately surrounding surface of the member (2) to prevent liquids flowing out of such perforations in use. The dished lower shell member (2) has a central lowermost region with drainage perforations (15) therethrough. The upper shell member (1) has at least one large perforation (16) and/or a plurality of small ones offset from those in the lower shell member (2). Preferably the upper shell member (1) has a central funnel inlet (17) for pouring liquids through the cover by way of the drainage perforations (15) in the lower shell member (2).

Effect of shell repair on shell strength in the gastropod Littorina irrorata

Abstract: Repair of damage to the outer lip of gastropod shells results in a scar whose presence could weaken the shell against crushing forces. Shell strength in Littorina irrorata (Say), measured as force required to break the shell between a moving bar and a stationary steel plate, was found to be similar for scarred and unscarred individuals. This suggests that scars do not affect crushing resistance adversely. Cracks tended to propagate along sutures and along growth lines. These seams appear to be more important than scars as lines of weakness in the shell of L. irrorata.

Cover apparatus with detachable compartments

Abstract: A vehicle frame element cover apparatus is provided which includes a flexible shell adapted to be snugly fit about the frame element and held in proper orientation by an adjustable strap and pockets which receive portions of the frame element. Zippered slits are formed in the shell to allow convenient attachment of the cover to the frame element and, when the slits are closed, the cover is drawn taut around the frame element. Preferably, the shell is formed of an inner layer of soft material and an outer layer of durable, wear-resistant material. Removable pouches may be mounted on the shell.

Shoe or boot

Abstract: The shoe consists of a shell (1) made of synthetic plastics material and has a bellows-like corrugation on the surface of the shell (1) in the area (2) of the roots of the toes. Ridges (3) and furrows (4) extending transversely to the longitudinal direction are provided, which, when viewed from above, are seen to be arranged asymmetrically and run backward towards the outside (10) of the foot. (FIG. 3).

Shielded electrical connector

Abstract: A shield member for an electrical connector comprises a stamped and formed metal shell having a mouth for receiving a mating connector shield comprising a lip having a planar resilient portion extending in the mating direction and a free end formed with a plurality of reversely bent, rigid projections protruding into an envelope defined by the profile of the mouth. Two shield members having interengageable latching means and a rear cable clamping portion of bifurcated hemi-frusto-conical shape can be pressed together about a connector terminating a shielded cable with the rigid projections protruding through windows in a housing of the connector into the envelope and the clamping portions gripping between them the cable shield.

Pressure roll for use in calenders or the like

Abstract: A pressure roll for use in a calender has a beam whose end portions are mounted in a stationary frame and which is spacedly surrounded by a hollow cylindrical shell. Groups of hydrostatic supporting elements are installed in the space between the shell and the beam, and each such group has several supporting elements, as considered in the circumferential direction of the shell. Each supporting element has several hydraulic pressure transmitting cylinder and piston units which are adjacent to each other, as considered in the circumferential direction of the shell. The axis of the shell is held in a supporting plane which includes the axis of the pressure roll as well as the axis of an adjacent roll, and such retention of the axis of the shell in the supporting plane is effected exclusively by regulating the pressure of hydraulic fluid in selected pressure transmitting units. The end portions of the shell are movable radially of the respective portions of the beam.

Rotational properties of shell-model states in fp-shell nuclei

Abstract: The relation between the microscopic shell model and the collective rotor model is investigated. As the first step an extensive shell-model calculation is performed on about twentyfp-shell nuclei with massA=52–60. It turns out that, with the model space and the effective interaction chosen, the shell model is well able to reproduce the experimental data in this mass region. As the second step the shell-model wavefunctions are used to calculate energies, electromagnetic moments and transition rates of states with spin up toJ=16. As the third step the observables calculated with the shell model are used to investigate whether these microscopic results can be reproduced by a simple rotational model. About twenty pure axially symmetric rotor bands, generated by the shell model, could be localized. Their properties are presented and discussed.

Solderable electrical contact

Abstract: A component and method are provided for making a soldered electrical connection between two mating members, in which a deposit of solder on the surface of one of the members is juxtaposed to a cooperatively shaped surface on the other member when the two members are mated, so that the solder will melt and bind the two surfaces when heated. The quality of this connection may be further improved by providing a resilient arrangement for urging the conforming surfaces together as heat is applied. In one form of contact element according to the invention a hollow, cylindrical metal shell with a longitudinal split provides a resilient fit into a mating member, such as a metal-lined hole on a printed circuit board. The shell is provided with a deposit of solder in a groove on its outer surface where the shell is to engage the metal lining of the hole.

Resonant acoustic scattering from elastic cylindrical shells

Abstract: The normal mode solution of the scattered pressure due to a normally incident plane acoustic wave on an infinitely long, air‐filled aluminum cylindrical shell in water is analyzed Our study yields a physical interpretation of normal mode contributions to the backscattering function The modes in the near‐soft (thin‐shell) region are compared to theoretical predictions and empirical observations Transitions from Rayleigh‐type surface waves to Lamb‐type waves are found to take place for thin shells A smooth transition of the first transverse wave on a thick shell to that of the first symmetric Lamb wave on a thin shell is shown to occur, and the inception of these thin‐wall modes is investigated as a function of shell thickness Also, the antisymmetric Lamb mode is shown to exist and its intermittent nature is examined

Discharge lamp device

Abstract: PURPOSE:To reduce the size of shell by arranging a ballast in a shell equipped with a base of small fluorescent lamp while shifting from the center and arranging starter parts in a void at the opposite side from the shifting direction CONSTITUTION:A small fluorescent lamp 1 is formed with a bulb 2, an electrode 5 provided on the bottom plate 4 and two L-shaped inner tubes 6 containing the electrode 5 while having the inner face coated with phosphor substance 7 A shell 8 having a base 9 and tubular drum 88 is fixed onto the bottom of lamp 1, then a ballast 10 is arranged such that the center B1 will be shifted in one direction by the distance (L) from the center S1 of shell 8 while a glow startor 11 and a noise prevention capacitor 12 are arranged in a void 55 at the opposite direction from the shifting direction Consequently the startor parts are brought near to the shell drum 88 to reduce influence of temperature thus to facilitate containing and to reduce the size of shell 8

Horizontally poured Fibrestone building construction

Abstract: In the Fibrestone Building Construction the outer or exterior shell or panel is formed of a plastic material such as concrete reinforced by a high concentration of fibers, such as glass or other fibrous material randomly disbursed in the mass of the moldable material such as concrete. If desired the fibers can be chopped up to accelerate their bonding in the mass of the moldable material. This moldable material and the fibrous reinforcement may be sprayed under pressure into a mold having a surface which it is desired to reproduce. The surface of the mold is reproduced faithfully, and a relatively thin but strong outer shell embodying the desired contour is thus formed. This outer shell or wall is assembled in a horizontal position, with its outer face down, with a frame of substantially uniform thickness throughout. All necessary insulation, wall reinforcements, appliance fittings, door and window cutouts and spaces for wall connectors and utility outlets are installed within the thickness of the framework. Concrete or other moldable material is then cast into the horizontally disposed framework to completely fill the space within the outer shell and the framework. After the cast material has attained an initial set the excess material is stricken off flush with the top of the framework to provide, when cured, a panel of uniform thickness and a smooth exterior surface. The fiber reinforced concrete which forms the desired exterior shell or wall is thus securely bonded to the cast concrete backing material to provide the Fibrestone wall which is a combination of the exterior fiber reinforced shell and the cast load bearing backing material.

Shell Elements for Cooling Tower Analysis

Abstract: Intending to achieve optimum finite element modeling of column supported cooling towers for seismic response studies according to the distributions of dominating bending and membrane stresses and intending to model the vulnerable shell‐column region using discrete column elements and quadrilateral shell elements, a set of elements is adopted, modified or extended. The set includes: (1) A 16 d.o.f. column element; (2) a 48 d.o.f. doubly curved quadrilateral general shell element; (3) a 42 d.o.f. doubly curved general‐membrane transition element; (4) a 21 d.o.f. and 39 d.o.f. doubly curved triangular membrane filler elements; and (5) a 28 d.o.f. doubly curved quadrilateral membrane element. Examples are given to evaluate a single type, combined types, and the whole set of elements with results in good agreement with alternative solutions. These elements may be used for accurate and efficient free vibration analysis of column supported cooling towers. The modeling may be used in seismic response analysis of ...