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Showing papers on "Shell (structure) published in 1986"


Journal ArticleDOI
TL;DR: This work describes the formulation of a 4-node shell element using a mixed interpolation of tensorial components, and presents a new 8-node element using this approach.
Abstract: We briefly discuss the requirements on general shell elements for linear and nonlinear analysis in practical engineering environments, and present our approach to meet these needs. We summarize and give further insight into our formulation of a 4-node shell element using a mixed interpolation of tensorial components, and present a new 8-node element using this approach. Specific attention is given to the general applicability of the elements and their efficient use in practice.

772 citations



Journal ArticleDOI
TL;DR: In this paper, the influence of small, non-axisymmetric imperfections in the middle surface and of a static load, on the amplitude of the forced oscillations of shells of revolution of zero curvature, was studied.

190 citations


Journal ArticleDOI
TL;DR: In this article, a finite element approximation of the so-called Mindlin-Reissner formulation for moderately thick elastic plates is considered and it is shown that stability and optimal error bounds hold independently of the value of the thickness.
Abstract: We consider a finite element approximation of the so-called Mindlin-Reissner formulation for moderately thick elastic plates. We show that stability and optimal error bounds hold independently of the value of the thickness. 1. Introduction. The so-called Mindlin-Reissner model for moderately thin plates is often used by engineers in connection with plate and shell problems. It is well known that many numerical schemes for this model are satisfactory only when the thickness parameter t is "not too small". For a very small t, some bad behavior (such as the "locking" phenomenon) might occur. Here we present a method which is uniformly good as t goes to zero, and we prove optimal error estimates for transversal displacement, rotations and shear stresses, with constants independent of t.

133 citations


Journal ArticleDOI
TL;DR: In this article, a rank-sufficient 4-node degenerated nonlinear shell element, termed the resultant-stress degenerated-shell (RSDS) element, is presented.
Abstract: In this paper, a resultant-stress degenerated-shell element is described and a variety of numerical examples, including the post-buckling analysis of an axially loaded perfect cylinder, are presented. The general degenerated nonlinear shell theory of Hughes and Liu is employed in deriving this resultant-stress degenerated-shell element. Contrary to the traditional integration through the thickness approach, which assumes no coupling between the in-plane and transverse material and structural response matrices, the present approach can permit use of arbitrary, three-dimensional (3-D) nonlinear constitutive equations. Furthermore, explicit expressions of the element matrices for a 4-node shell element are developed. This rank-sufficient 4-node shell element, termed the resultant-stress degenerated-shell (RSDS) element, avoids the need for the costly numerical quadrature function evaluations of the element matrices and force vectors. And thus there are large increases in computational efficiency with this method. The comparisons of this RSDS element with six other shell elements are also given in this paper.

128 citations


Patent
22 Oct 1986
TL;DR: A rotary pressure applying roll which defines with a parallel complementary roll a nip for a running web of paper, textile or other flexible sheet material in a calender or the like has a cylindrical shell surrounding a stationary carrier in the form of a rigid shaft as mentioned in this paper.
Abstract: A rotary pressure applying roll which defines with a parallel complementary roll a nip for a running web of paper, textile or other flexible sheet material in a calender or the like has a cylindrical shell surrounding a stationary carrier in the form of a rigid shaft A bearing element is installed between the shell and the carrier and several hydraulic pressure generating devices are mounted between the carrier and the bearing element to urge the latter against the internal surface of the shell The pressure generating devices are spaced apart from each other, as considered in the circumferential direction of the shell, and the cylinder chamber of each such device can receive pressurized hydraulic fluid at a different pressure The axis of a main pressure generating device is normally located in the common plane of the axes of the shell and of the complementary roll The other device or devices are installed at the one and/or the other side of such plane and can be operated to counteract forces acting substantially tangentially of the shell The carrier and the bearing element have cooperating spherical, flat and/or cylindrical guide faces which enable the bearing element to pivot about an axis that is parallel to the axis of the shell

114 citations


Journal ArticleDOI
TL;DR: The close agreement between calculated versus observed body chamber lengths in five species of Mississippian ammonoids shows that neutral buoyancy, and (with one exception) Nau- tilus-like orientations, were at least feasible for these species.
Abstract: The buoyancy, stability, and orientation of a shelled cephalopod in water are the predictable products of shell geometry, body chamber length, and such physical parameters as shell, tissue, and water densities. Given such physical characteristics as shell geometry, shell, tissue, and water densities, and shell thickness, the hydrostatic characteristics of planispiral shelled cephalopods, including orientation, centers of mass and buoyancy, stability, and neutrally buoyant body chamber length, can be calculated and simulated using microcomputer-based techniques. Individual variables such as geometry, body chamber length, and shell thickness are linked in a calculable manner to orientation, neutral buoyancy, and stability. Living Nautilus provides a means of testing the model and for making hydrostatic comparisons between ammonoids and nautiloids. The close agreement between calculated versus observed body chamber lengths in five species of Mississippian ammonoids shows that neutral buoyancy, and (with one exception) Nau- tilus-like orientations, were at least feasible for these species.

110 citations


Patent
21 Feb 1986
TL;DR: In this paper, a spiral coil of tubing is wound helically about the axis of the shell and sized to fit the inner and outer walls with limited radial clearance, which is axially spaced from one another to define a spiral flow path within the shell cavity for the fluids to first flow.
Abstract: The heat exchanger is made up of a shell having a coaxial tubular outer and inner wall with end plates attached thereto to enclose a tubular shell cavity provided with an inlet and outlet for a first fluid. Within the shell cavity is a spiral coil of tubing through which flows a second fluid. The coil is wound helically about the axis of the shell and sized to fit the inner and outer walls with limited radial clearance. The coils are axially spaced from one another to define a spiral flow path within the shell cavity for the fluids to first flow. The radial and axial clearance establish a spiral flow path and an axial flow path which are relatively sized to cause the first fluid to travel in a spiral motion, thereby enhancing heat transfer between the first and second fluids.

102 citations


Patent
22 Jan 1986
TL;DR: An electrical connector for twin axial cable (100,100) comprises; a first assembly (4,4) comprised of a conductive outer shell (6,6), a first dielectric body (8,8), a conductiv inner shell (10,10), and a second dielectrical body (12,12); a second assembly (60,60) for insertion in the outer shell and for electrical connection with the inner shell, comprising a first conductive body (62,62) a conductives ferrule (64,64) on the first conductives
Abstract: An electrical connector (1, 2) for twin axial cable (100,100) comprises; a first assembly (4,4) comprised of a conductive outer shell (6,6), a first dielectric body (8,8), a conductive inner shell (10,10), and a second dielectric body (12,12); a second assembly (60,60) for insertion in the outer shell (6,6) and for electrical connection with the inner shell (10,10) comprises a first conductive body (62,62) a conductive ferrule (64,64) on the first conductive body (62,62) for connection with a corresponding electrical conductor (104,104), a third dielectric body (66,66), an electrical contact (70,70) for connection with a corresponding electrical conductor (102,102) of a twin axial cable (100,100), and a second conductive body (72,72) for establishing electrical connection of a conductive sheath (106,106) of a twin axial cable (100,100) and a barrier (108,108) in the outer shell (6,6) for limiting displacement of the conductive sheath (106,106) along the outer shell (6,6).

85 citations


Journal ArticleDOI
TL;DR: In this paper, the authors apply the method of asymptotic expansions to the general three-dimensional equations for the equilibrium of nonlinearly elastic shells with specific geometries, subjected to suitable loadings and boundary conditions.
Abstract: The method of asymptotic expansions, with the thickness as the small parameter, is applied to the general three-dimensional equations for the equilibrium of nonlinearly elastic shells with specific geometries, subjected to suitable loadings and boundary conditions. Then it is shown that the leading term of the expansion is the solution of a system of equations equivalent to those of Marguerre-von Karman (the case of a clamped shell is also considered). In addition, without making any a priori assumption regarding the variation of the unknowns across the thickness of the shell, it is found that the displacement field is of Kirchhoff-Love type, and that the stresses have polynomial variations with respect to the thickness.

80 citations


Journal ArticleDOI
TL;DR: A model based on geometrical crystal growth considerations is proposed for the deposition of the crocodilian, testudinian and avian eggshells in this paper, which shows that the organic component does not appear to control crystal growth, but instead acts as a reinforcing fibrous network.
Abstract: A model based on geometrical crystal growth considerations is proposed for the deposition of the crocodilian, testudinian and avian eggshells. In each shell column, crystal deposition is initiated at a single location, from which growth fans out at all angles to the shell normal. In both calcitic and aragonitic shells, growth is in the [001] direction, resulting in an increase in the degree of (001) preferred orientation with distance from nucleation. Where there is unhindered crystal growth, the shells show a crystalline fracture morphology, and the degree of texture that develops is a simple function of the column radius. This type of growth makes up the whole of the testudinian shell, the inner 0.3-0.4 (30-40%) of the thick ratite shells and the cone layer of the other avian shells. At the start of the palisade layer of the avian shell, the onset of deposition of the organic component coincides with a hindrance to texture development, which thereafter proceeds at a lower rate. A further hindrance occurs about halfway through the shell, probably caused by a change in the physical characteristics of the organic network. The degree of texture that develops in the avian shell is a function of the column radius and the degree of physical hindrance presented by the organic network. The palisade layer of the avian shell has a composite fracture morphology resulting from the intermingling of the network with the inorganic phase. The organic component does not appear to control crystal growth, as previously believed, but instead acts as a reinforcing fibrous network.

Journal ArticleDOI
TL;DR: In this article, a cylindrical shell which is reinforced at regular intervals by flexible stiffeners parallel to the shell generator is considered, and the structure effectively constitutes a one-dimensional periodic system and is analyzed as such.

Journal ArticleDOI
TL;DR: In this paper, the mass distribution of large argon clusters formed about positive ions in a free jet expansion was measured and the results support an icosahedrally derived shell model of cluster structure through completion of the fourth shell.

Journal ArticleDOI
TL;DR: Inextensional collapse mechanisms for axial crumpling of thin-walled circular cones and frusta (truncated circular cones) are presented in this paper, where shortening of the (thin) shell height is achieved by folding in a non-symmetric diamond mode about stationary circumferential and inclined plastic hinges; collapse proceeds progressively from the narrower end of the conical shell during the passage of a travelling hinge.

Journal ArticleDOI
TL;DR: In this article, a 12-d.o.f, geometrically non-linear, doubly curved, thin shell finite element of revolution with laminate composite materials was used for free vibration analysis of a pneumatic tire without suspension.

Journal ArticleDOI
TL;DR: In this paper, a non-linear shallow thin shell element is described, which is a curved quadrilateral one with corner nodes only, at each node, six degrees of freedom (i.e. three translations and three rotations) make the element easy to connect to space beams, stiffeners or intersecting shells.
Abstract: A non‐linear shallow thin shell element is described. The element is a curved quadrilateral one with corner nodes only. At each node, six degrees of freedom (i.e. three translations and three rotations) make the element easy to connect to space beams, stiffeners or intersecting shells. The curvature is dealt with by Marguerre's theory. Membrane bending coupling is present at the element level and improves the element behaviour, especially in non‐linear analysis. The element converges to the deep shell solution. The sixth degree of freedom is a true one, which can be assimilated to the in‐plane rotation. The present paper describes how overstiffness due to membrane locking on the one hand and to the sixth degree of freedom on the other hand can be corrected without making use of numerical adjusted factors. The behaviour of this new element is analysed in linear and non‐linear static and dynamic tests.

Journal ArticleDOI
TL;DR: Data support the hypothesis that selection to resist prying forces has been an important feature in the evolution of limpet shell morphology.
Abstract: The feeding behavior of rocky intertidal crabs in the tropical and temperate eastern Pacific was studied in relation to specific mechanical properties of the shells of their limpet prey. A series of laboratory experiments, involving direct observations, records of shell remains, and measurements of the forces generated by a feeding crab, showed that by far the most common feeding technique was to pry the margin of the limpet shell away from the substratum. The pattern of deformation in models of limpet shells subject to a similar prying force indicated (1) that the greatest stress on the shell was at the point of force application at the shell margin and (2) that the thickness of the shell margin contributed more to shell strength than did thickness in more apical regions of the shell. Measurements of the strength of real shells provided further support for this latter conclusion.In addition, the strength of foot attachment, which sets the maximum prying force that the shell can experience, closely parall...

Journal ArticleDOI
TL;DR: An analysis shows that atomic inner-shell states can be strongly excited by coherently driven outer-shell electrons and a substantial fraction of the absorbed energy can be channeled into inner- shell excitation.
Abstract: An analysis shows that atomic inner-shell states can be strongly excited by coherently driven outer-shell electrons. A time-dependent Hartree-Fock treatment illustrates the nature of this nonlinear intershell coupling. A substantial fraction of the absorbed energy can be channeled into inner-shell excitation.

Patent
11 Jun 1986
TL;DR: In this article, a continuous flow centrifugal processing system for separating whole blood into fractional components includes a molded bowl-shaped outer shell dimensioned to fit within a rotatably-driven casing on an associated centrifuge apparatus.
Abstract: A continuous flow centrifugal processing system for separating whole blood into fractional components includes a centrifugal separator unit having a molded bowl-shaped outer shell dimensioned to fit within a rotatably-driven casing on an associated centrifuge apparatus. A bowl-shaped inner shell disposed within the outer shell forms therewith a thin separation channel radially spaced from the axis of rotation wherein fractions are separated from the whole blood under the influence of centrifugal force. A rotating seal carried on the processing chamber between ports in the chamber and the non-rotating portions of the system. The outer shell includes a relatively thin side wall portion which is inwardly biased toward a side wall portion on the inner shell when seated in the casing. A plurality of projections on the side walls limit inward deformation of the outer shell to maintain a very close concentric spacing between the shell members to facilitate rapid separation of blood flowing through the chamber. By reason of the shell members being molded, the processing chamber can be economically produced in large quantities for disposable one-time use.

Journal ArticleDOI
TL;DR: In this article, the effect of the initial tensions due to the rotation of a rotating cylindrical shell on the frequency of travelling waves is analyzed for three kinds of boundary conditions (i.e., both ends (A) clamped, (B) simply supported without axial constraint, and (C) just supported with axial constraints).

Journal ArticleDOI
TL;DR: The geometry and anisotropic ultrastructure of the tympanic membrane are used in combination with curvilinear shell equations to formulate a general continuum model describing its dynamic behavior, which is shown to reproduce a large manifold of experimentally observed frequency and excitation-dependent vibrational shapes.
Abstract: The geometry and anisotropic ultrastructure of the tympanic membrane are used in combination with curvilinear shell equations to formulate a general continuum model describing its dynamic behavior. Primary terms appearing in the model are associated with shell membrane restoring forces, bending‐type structural damping, and transverse inertia. Since the model is based extensively on the physical characteristics of the membrane, it is relatively easy to account for differences between species as well as pathological conditions. The fibrous structure and cone‐shaped geometry, readily apparent in mammalian eardrums, introduce several small parameters into the model that are exploited in order to construct a closed‐form asymptotic solution. The solution includes the coupling to the three‐dimensional motion of the ossicular chain and it includes the frequency‐dependent pressure distribution in the auditory canal. When applied to the cat eardrum, this asymptotic solution is shown to reproduce a large manifold of experimentally observed frequency and excitation‐dependent vibrational shapes. In addition to the shapes, transient amplitude and phase data for the cat are reproduced.


Journal ArticleDOI
TL;DR: In this article, a new 6-node triangular bending element (called DKTP) based on a discrete Kirchhoff model is presented, and a corresponding new flat-shell element, DLTP, having quadratic variation of in-plane displacement is also presented.
Abstract: We present a new 6-node triangular bending element (called DKTP) based on a discrete Kirchhoff model. A corresponding new flat-shell element, DLTP, having quadratic variation of in-plane displacement is also presented. This element has 6 degrees-of-freedom (u, v, w, θx, θy, θz) at each corner node and 3 degrees-of-freedom (u, v, w) at each mid-side node. Detailed numerical experimentation is presented to demonstrate the efficiency and reliability of these elements.

Journal ArticleDOI
TL;DR: In this article, a simple moving hinge model which describes the deformation of a ring into a "dumbbell" shape is proposed and closed-form solutions are derived for the pressure necessary to initiate and propagate the buckle down the tube.

Patent
14 Apr 1986
TL;DR: In this article, a container device for transporting and storing coils of wire which protect the coils from damage is described, which comprises a circumferential shell having a recessed annular bottom element inwardly adjacent the upper edge of the shell to form an open-topped annular receptacle in the upper side of the device.
Abstract: A container device for transporting and storing coils of wire which protect the coils from damage. The device comprises a circumferential shell having a recessed annular bottom element inwardly adjacent the upper edge of the shell to form an open-topped annular receptacle in the upper side of the device. The inner edge of the bottom element extends upwardly to provide a hollow central post concentric with the outer shell. The underside of the device is formed with a closure wall coextensive in width with the recessed bottom element and is adapted to form a closure for the open-topped receptacle of the subjacent container device when the devices are stacked one upon another. Sockets for a forklift truck are provided in the circumference of the shell to enable the forklift truck to manipulate the devices into and out of position in the stack.

Journal ArticleDOI
TL;DR: An inextensional collapse mechanism for the crumpling of thin-walled, grooved tubes and tubes without any discontinuities (non-grooved), when subject to axial load is considered in this article.


Patent
27 Oct 1986
TL;DR: An insulated can holder as discussed by the authors is defined by an outer shell of a moldable, resilient plastic material and an inner, removable insulating liner inside of the outer shell, and the shell carries at least one flat, indicia bearing and integral portion whose interior surface bears against the insulating lintern to increase the contact and friction between a can and the liner.
Abstract: An insulated can holder defined by an outer shell of a moldable, resilient plastic material and an inner, removable insulating liner inside of the outer shell. The shell carries at least one flat, indicia bearing and integral portion whose interior surface bears against the insulating liner to thereby define a nin-circular cross section of the holder and thereby increase the contact and friction between a can and the liner.

Journal ArticleDOI
TL;DR: In this article, an arbitrarily laminated, anisotropic cylindrical shell of finite length, under uniform internal pressure, is analyzed using Love-Timoshenko's kinematic relations and under the framework of classical lamination theory.
Abstract: An arbitrarily laminated, anisotropic cylindrical shell of finite length, under uniform internal pressure, is analyzed using Love-Timoshenko's kinematic relations and under the framework of classical lamination theory. The previously obtained solutions for asymmetrically laminated orthotropic (cross-ply) as well as unbalanced-symmetric and balanced-unsymmetric (angle-ply) cylindrical shells under the same loading conditions have been shown to be special cases of the present closed-form solution. Numerical results have been presented for a two-layer cylindrical shell and compared with those obtained using finite element solutions based on the layerwise constant shear-angle theory. These are expected to serve as benchmark solutions for future comparisons and to facilitate the use of unsymmetric lamination in design.

Patent
06 Aug 1986
TL;DR: In this article, an auxiliary lock is disclosed on which it is possible to change its length by turning and moving a combining plate to cause an extensible shell to turn and move around a cylinder.
Abstract: An auxiliary lock is disclosed on which it is possible to change its length by turning and moving a combining plate to cause an extensible shell to turn and move around a cylinder so that a projection in the extensible shell may extend into one of two positioning holes in the cylinder to form the short length or in the other positioning hole to form the long length. At the same time, a connecting pin in a deadbolt moves in a U-shaped slot and a reversed U-shaped slot in a moving plate operable by a mechanism in the combining plate.