Showing papers on "Shell (structure) published in 1980"

Transition finite elements for three‐dimensional stress analysis

Abstract: This paper presents isoparametric formulation for the three-dimensional transition finite elements. The transition finite elements are necessary for applications requiring the use of three-dimensional isoparametric solid elements and the curved shell elements. These elements provide proper connections between the two portions of the structure modelled with three-dimensional solids and the curved shell elements. The element properties are derived and presented in detail. Numerical examples are also presented to demonstrate the accuracy and the applications of such elements in three-dimensional stress analysis.

Shell form in the biconvex articulate Brachiopoda; a geometric analysis

Abstract: Using a geometric model of shell morphology, it is demonstrated that biconvex brachiopods occupy only a small region of the potential geometric space available to organisms with planispiral exoskeletons composed of two articulated valves. Measurements taken for a sample of 324 genera of the articulate orders Pentamerida, Rhynchonellida, Spiriferida, and Terebratulida were analyzed using a simple geometric model of shell form and ontogeny. The frequency distribution of brachiopod shell morphologies exhibited by the four orders represents the biological optimization of the spatial relationships between area and volume. Biconvex brachiopods develop shells which are designed to minimize shell surface area while maximizing internal shell volume. The means by which optimization is achieved is related directly to the effects of increase in absolute size during ontogeny. The boundaries upon shell geometries utilizable by biconvex brachiopods are determined by (1) limitations of articulation, and (2) limitations of surface and volume.

Headgear with energy absorbing and sizing means

Abstract: A headgear comprising a helmet shell and a combination of energy-absorbing and sizing means mounted on the inside surface of the shell. The combination includes a crown-engaging structure either in the form of a web suspension or an air-inflatable means. These pad structures comprise curved assemblies which engage the forehead and back of the wearer's head and the pad structures enable automatic alignment of the helmet along the long axis of the head whereby the air-inflatable side members are operated after the helmet has been put on the head. Air inflatable sizing means are located intermediate the pad structures at the front and back of the shell, and these sizing means engage the respective sides of the werer's head to provide a side-to-side fit on the head. A combination serving as a sizing means and energy-absorbing means is located on the lower rear inside wall of the shell. Separate energy-absorbing pad structures are located on the front and back inner walls of the shell.

Skeletal load-bearing structures for motor vehicles

Abstract: A skeletal load-bearing structure for a motor vehicle includes a plurality of tubular girders joined together by connectors. Each girder and each connector is composed of at least two shell elements of thin sheet metal provided with longitudinal flanges by means of which the shell elements are joined together. Each connector shell element has a plurality of smoothly merging arm portions which together with corresponding portions of the other shell elements of the same connector form a plurality of tubular connection stubs to which respective ones of said girders are connected.

Differential scanning microcalorimeter

Abstract: A differential scanning microcalorimeter comprises an adiabatic shell accommodating two capillary calorimetric chambers. One end of each chamber extends beyond the shell and passes through a heat bypass. At least one chamber is contrived in the form of two capillary tubes in thermal contact with each other, with the ends located inside the shell communicating with an end of the other chamber also located inside the shell.

Ultrastructural morphology of the shell and shell membrane of eggs of common snapping turtles (Chelydra serpentina).

Abstract: Common snapping turtles (Chelydra serpentina) lay nearly spherical, flexible-shelled eggs having an outer mineral layer composed of calcium carbonate in the aragonite form. The mineral layer is arranged into loosely organized groups of nodular shell units, with numerous spaces (or pores) between adjacent shell units. Shell units are structurally complex, consisting of an inner tip that is morphologically distinct from the main body of the shell unit. Contained within an intact shell unit at the interface of the tip and the main part of the shell unit is the central plaque, an apparent modification of the shell membrane that may serve to nucleate calcification of shell units during shell formation. The tips of shell units are firmly attached to a single, multilayered shell membrane throughout much of incubation. The calcareous layer begins to detach from the shell membrane about half-way through incubation, and changes in shell morphology attending this detachment indicate that snapping turtles may use the shell as a source of calcium during embryogenesis. The arrangement of the mineral layer into groups of shell units, the large number of spaces between shell units, and little or no interlocking of crystallites of adjacent shell units apparently are factors contributing to the ability of these eggs to swell as they absorb water.

Heat exchanger assembly

Abstract: A heat exchanger assembly has an elongated shell provided with fluid inlet and fluid outlet openings. An elongated bundle assembly is received within the shell. The bundle assembly has a plurality of elongated tubes extending generally longitudinally and a plurality of generally parallel fin plates which are transversely oriented. The bundle assembly has a top sheet and a bottom sheet. The bundle assembly support is interposed between the bottom sheet and the shell. A baffle is provided in the form of an elongated plate extending generally diagonally between the top sheet of the bundle assembly and the shell. In a preferred form, the baffle plate is provided with an underlying seal which is interposed between the baffle plate and the top sheet and has an upper edge which is of generally complementary curvature with respect to the adjacent portions of the shell and may take the form of a portion of a sine wave. The bundle assembly support may provide cooperation to facilitate insertion of the bundle assembly into the shell and removal of the same therefrom. The bundle assembly support may cooperate with the shell in defining a condensate receipt reservoir.

The Intrinsic Equations of Shell Theory with Some Applications

Abstract: The scope of the general intrinsic equations of nonlinear shell theory is widened by (tentative) refined estimates of the errors in the equations. Applications are made to the nonlinear theory of cylindrical bending of a circular cylindrical shell and to axisymmetric deformations of shells of revolution. The paper concludes with mention of some further applications, including the linear theory of shells of slowly varying curvature.

Refined Theories for Nonhomogeneous Anisotropic Cylindrical Shells: Part II-Aplication

Abstract: First approximation thin shell and higher order thick shell correction theories are derived for nonhomogeneous anisotropic cylindrical elastic shells by use of the method of asymptotic expansion in terms of a small parameter along with Reissner's variational principle. The advantages of employing the asymptotic method, in addition to its systematic nature, are that no a priori kinematic or static assumptions need be made or both, that trasverse stresses develop naturally (even in the thin shell analysis) and that thick shell theories follow automatically. Use of the combined method generates various theories based upon different combinations of axial and circumferential length scales introduced in the nondimensionalization of the coordinates. The first approximation theories derived herein for anisotropic materials have their counterparts for isotropic materials. They are: (1)Simplified Donnell theory; (2)simple bending theory; (3)semimembrane theory; and (4)complete Donnell theory.

A numerical study of MHD equilibrium and stability of the spheromak

Abstract: The MHD-stability of spheromak-type equilibria from the classical spheromak configuration to the diffuse-pinch limit is analysed numerically. It is found that oblate configurations of ellipticity 0.5 have optimum stability properties with regard to internal MHD-modes and can be stabilized up to an engineering β of 15% (defined with respect to the applied external field strength for equilibrium). Stability to global modes requires that a conducting shell surround the plasma. The location of the shell is dependent on geometry and current profile, but realistic configurations that are stable to all ideal MHD-modes have been found with the shell located at about 1.2 of the minor radius.

Infant swing carrier

Abstract: An infant carrier has a handle which can be detachably coupled to a hanger on a swing. The handle is U-shaped and pivotably connected at its free ends to the carrier shell body by a latch means so that the handle can be latched in different angular positions.

Computation of stresses, strains, and deformations of tires

Abstract: Tire construction, loading, and response are reviewed, and a hierarchy of tire structural analysis models is presented, progressing from simple to complex. Model descriptions and applications include ring, string, and beam-on-elastic foundation models, netting analysis, membrane analysis, thin shell analysis, finite element models, constant strain triangular element models, and analysis of shell and isoparametric elements. Future developments in the analysis of tire displacement, stress, and strain are indicated (e.g. axisymmetric modeling, effect of footprint loading, use of contact algorithms with stick-slip capabilities).

Railway hopper car

Abstract: A rail car includes substantially flat plate extensions interposed between upper and lower sections of the shell of the car to increase the internal volume of the car. The extensions are supported by lateral supports which extend laterally in the interior of the car and by longitudinal support beams also in the car interior which extend longitudinally of the extensions, are intersected by the lateral supports, and substantially prevent internal pressure in the car from being applied to the extensions.

Metal shell golf club head, with keel

Abstract: A golf club head comprises: p1 (a) a metallic shell having the exterior form of said head, (b) the head having a front face adapted to strike a golf ball, and upper and lower surfaces, said lower surfaces defining a downwardly projecting keel which extends rearwardly relative to said front face, the keel having a downwardly convex surface which is forwardly and rearwardly elongated, said lower surface of the head having underside faces at opposite sides of the keel with each such face having downwardly concavity, (c) said keel defining a portion of said shell.

Limited angle electric rotary actuator

Abstract: An electric rotary actuator for producing rotation through a limited angle comprises a rotor winding made of a plurality of thin loop coils arranged in a continuous cylindrical framework as part of a rotor shell. The rotor shell lies in an annular flux gap defined by a stator magnet assembly and a flux return means. Each pair of adjacent axially extending limbs of adjacent loop coils lies opposite to and cooperates with a respective stator pole face. This winding arrangement helps to optimize the torsional resonance characteristics of the rotating mass.