Showing papers on "Shell (structure) published in 1991"

Controlled deflection roll

Abstract: In a controlled deflection roll having a roll shell rotatable about a stationary carrier and braced by one or more support elements against the stationary carrier, the roll shell comprises an inner roll shell part and an outer roll shell part which, during operation of the controlled deflection roll, form a press or force fit with respect to one another, for instance, due to excess pressure in the interior of the controlled deflection roll or due to elastic pre-biasing of the parts of the roll shell. Upon pressure relief or the existence of negative pressure within the controlled deflection roll a play or clearance is formed between the outer roll shell part and the inner roll shell part of the roll shell which enables dismantling and exchange of the outer roll shell part of the roll shell without the need to dismantle the controlled deflection roll or to remove such from the machine.

Dual roller apparatus for pressure fixing sheet material

Abstract: A fixing and developing apparatus in which sheet material to be treated is passed through a high pressure nip defined by a pair of rollers. At least one of the rollers may have a composite construction. The composite roller includes an elongated tubular shell with a pressure applying external surface, an elongated core positioned within the tubular shell, and an elastomeric material disposed between the core and shell to support the shell on the core. The core may be of a number of configurations and may increase in transverse cross-sectional dimension from the respective ends of the core toward the center of the core. The core may taper continuously or in discrete steps from its center toward its first and second ends. In addition, the core may have a longitudinal cross-section with a crown in the shape of a beam deflection curve for a simply supported, uniformly constant cross-section beam. The shell may be similarly configured along its interior surface. Also, the elastomer may be compressed at the center of the roller relative to the ends of the roller to preload its center portion.

Thermal vibration and melting from a local perspective.

Abstract: X-ray-absorption fine-structure (XAFS) measurements of lead from 10 K through and above the melting transition at 600 K have been carried out. A cumulant expansion analysis provides data on the first four moments of the radial distribution of the first shell, which are used to construct a consistent temperature-dependent radial distribution function for the solid. The distribution is one given by a simple one-dimensional anharmonic oscillator. The results also demonstrate that XAFS, a local probe, can clearly distinguish between the liquid and solid state. In the liquid, the apparent coordination number is decreased by the fraction of the time the atom is diffusing. An improved method for determining the background at low {ital k} is discussed that gives a reliable determination of the background much closer to the threshold than allowed by standard methods.

Structural shell with reinforcing ribs connected via perforations

Abstract: The manufacture of lightweight components having high strength properties can be improved in that a bowl-shaped shell (1) has reinforcing ribs (3) made from injected-on plastic in its interior (2) which are connected to the shell (1) at discrete connecting points (11) via perforations (12) in the shell (1), through which the plastic passes, extending beyond the surfaces of the perforations (12).

L-shell absorption spectrum of an open-M-shell germanium plasma: Comparison of experimental data with a detailed configuration-accounting calculation.

Abstract: The radiative opacity of a near local thermodynamic equilibrium, open-M-shell Ge plasma has been measured in the region of the 2p-3d and 2p-4d transition arrays, and is compared for the first time with the results of a detailed configurafion-accounting calculation which includes an approximate treatment of term widths. The plasma was generated by radiation heating using thermal×radiation from a laser-produced gold plasma

Insulated paper cup

Abstract: An insulated paper cup having inner and outer frustoconcial shells, the inner shell being more tapered than the outer shell. The upper rims of both shells are outwardly curled and joined together. The outer shell has a recessed bottom upon which the bottom of the inner shell rests. The inner surface of the inner shell is coated with a plastic film such as polyethylene.

Plastic outer shell for a computer connector

Abstract: A plastic outer shell for a DIN/MINI DIN computer connector has a hollow, elongated rear end extending from the body thereof at one end, the hollow, elongated rear end made from a flexible plastic material and integrally formed of a plurality of spaced, straight ribs in longitudinal direction and a plurality of spaced, curved ribs in transverse direction, the spaced, curved ribs permitting the cross sectional area defined in the hollow, elongated rear end to be expanded for holding cables of different outer diameter

Stability of a shell around a black hole.

Abstract: We study the mechanical stability of a static, infinitely thin, spherically symmetric massive shell surrounding a classical Schwarzschild black hole. The shell is taken to have a non-negative surface energy density, and a speed of sound not greater than the speed of light. We show that the shell is stable against radial perturbations only outside a critical radius which is always larger than the radius of the circular photon orbit. The surface energy density of a stable shell is always larger than twice the surface pressure, and thus satisfies the dominant energy condition by a wide margin. We briefly discuss the effects of Hawking radiation in view of a path-integral approach to black-hole thermodynamics developed by York and collaborators. Our results suggest that a macroscopic thermal equilibrium situation associated with the canonical ensemble in this approach may not be realizable with a thin matter shell in Lorentzian spacetime.

Mold behavior and its influence on quality in the continuous casting of steel slabs: Part II. Mold heat transfer, mold flux behavior, formation of oscillation marks, longitudinal off-corner depressions, and subsurface cracks

Abstract: Axial heat-flux profiles have been determined quantitatively from temperature measurements conducted on a slab mold under routine operating conditions. As in earlier studies, the heat flux was observed to have a maximum value at the meniscus and to decline with increasing distance down the mold. The mold heat flux increased with increasing casting speed and was greater with a mold powder having lower viscosity and melting point being applied as lubricant. The heat extraction was largest while casting 0.29 pet carbon steel and least for a 0.09 pet carbon grade; reducing the depth of the submerged entry nozzle increased the heat flux slightly in the upper region of the mold. Most significant was the higher heat flux observed at the meniscus of the outside-radius face, attributable to the locally greater copper plate thickness compared to that of the opposite broad face. All of the measurements can be explained straightforwardly by heat flow in the vicinity of the meniscus and the resulting behavior of the so-called slag rim adjacent to the mold wall. It is postulated that the difference in copper plate thickness between the two broad faces at the meniscus causes the slag rim to be smaller on the outside-radius face which gives rise to shallower oscillation marks, as observed, higher heat transfer, and a slightly thicker solid shell. The dissimilar behavior has implications for quality because the inside-radius shell, experiencing reduced heat extraction, cools and shrinks less than the outside-radius shell. Thus, for a given end-plate taper, the narrow face of the slab adjacent to the inside radius can push against the end plate, accelerating copper wear, and, owing to squeezing of the broad face, cause an off-corner depression and subsurface crack toward the mold exit. If this is correct, maintenance of the same copper plate thickness at the meniscus is fundamental to preventing such an occurrence. Moreover, adjustment of the heat extraction at the meniscus should be achievable by changing copper plate thickness, mold coating thickness/conductivity, cooling water velocity, cooling channel configuration, and mold flux composition for a given steel grade.

An investigation of a finite rotation four node assumed strain shell element

Abstract: The paper presents a shell formulation based on the ‘degenerated solid approach’. The theory employs covariant strains and performs explicit integration through the shell thickness. The rigid body motion is exactly represented. The consistent tangent stiffness matrix is evaluated for the four node quadrilateral. It is shown, in the final part, that this type of element, which distinguishes itself by a very simple and easily understandable theory, gives good answers for linear as well as non-linear applications.

Development of deuterated polystyrene shells for laser fusion by means of a density‐matched emulsion method

Abstract: High quality, microdeuterated polystyrene shells were fabricated using a density‐matched emulsion method. The diameter and wall thickness of the shell ranged from 100 to 1500 and 3 to 15 μm, respectively. The sphericity, the wall thickness uniformity, and the surface smoothness were 99.8%, 99.3% and <0.1 μm, respectively. A defect on the inner surface of the shell was smeared by replacing water in the shell with ethanol prior to the final drying process.

Multiplepole electrical connector

Abstract: A multiple pole electrical connector includes a cylindrical metal shell (6); and insulation housing (7) placed within the metal shell and having a plurality of ground member recesses (20) formed on its circumferential surface; a plurality of detachable terminals (8) supported by the insulation housing, one of the detachable terminals serving as a ground terminal (9); and a detachable ground member (23) mounted on the ground terminal with a shell contact portion (24) thereof fitted in the ground member recess such that when the insulation housing is placed within the metal shell, the shell contact portion comes into close contact with an inside of the metal shell

The zero-normal-stress condition in plane-stress and shell elastoplasticity

Abstract: The use of elastoplastic models in calculations of shell and plate structures, or more generally in stress situations in which one normal stress component is forced to be zero, usually leads to complicated algorithms. This leads to cumbersome programming, which in turn may easily entail errors in the code. Moreover, the fraction model for cyclic plasticity cannot be used within most algorithms since the normal stress perpendicular to the plane of the element is not necessarily zero for each of the fractions. In this contribution an algorithm will be presented that enforces a zero-stress condition at integration point level, while obviating the need to develop special subroutines for plane-stress or shell plasticity. The algorithm is based upon an implicit integration of the stress-strain law and can be combined with the newly developed technique of consistent tangent operators.

Recyclable microwavable container with a removable outer shell

Abstract: A microwavable container useful in the microwave heating of items, particularly foodstuffs, comprises readily separable components. An outer shell which will remain relatively cool and, therefore, capable of being handled, surrounds an inner shell capable of sustaining high temperatures. A consumer may heat a food product in the inner shell of the present invention without risking contact with that inner shell when the inner shell becomes hot. After use, the components are readily separable for separate recycling processes.

Right angle coaxial jack connector

Abstract: A right angle coaxial connector jack (10) includes a metal shell (12) with integral metallic grounding pins (30) and a metallic cap (32), locking insulators (50, 58) within the shell carrying a signal contact (38). The shell (12) includes an aperture in the rear face facilitating a straight action assembly of elements to seal said connector against contamination and radiation.

Sound scattering by resonantly excited, fluid-loaded, elastic spherical shells

Abstract: The scattering of sound waves by an air‐filled, elastic, spherical shell in deep waters, in the frequency domain is analyzed. This exact analysis is based on the classical formulation of three‐dimensional elastodynamics, for fluid‐loaded spherical shells of arbitrary thickness. Form functions, residual responses, and the partial‐wave expansions of both, are determined. Results are displayed in relatively wide frequency bands for various increasing shell thicknesses. The resonance features in the sonar cross sections (SCS) are isolated by means of a new hybrid modal background that substantially improves the results found with the earlier (rigid/soft) backgrounds of the resonance scattering theory (RST). The resonance features in the SCSs that correspond to each mode, and also to each of the various shell waves that propagate around its periphery are isolated. There seem to be over half‐a‐dozen shell (generalized Lamb and Stoneley) waves manifesting their influence in the SCSs within the examined band. Thr...

A comparison between the boundary element method and the wave superposition approach for the analysis of the scattered fields from rigid bodies and elastic shells

Abstract: The steady state analysis of the scattering of plane acoustic waves from submerged rigid and elastic bodies using two approaches is presented. The first approach uses a combined finite element/boundary element (FE/BE) methodology. The NASA structural analysis (NASTRAN) program is used to formulate the structural matrices based on the finite element method (FEM). The surface integral equation radiation and scattering (SIERRAS) program creates the fluid matrices based on the boundary element method (BEM) and solves the coupled fluid-structure interaction problem. A superparametric boundary element (BE) with nine nodes is employed. The combined Helmholtz integral equation formulation (CHIEF) is employed to provide a unique solution for all frequencies. In the second approach, the superposition method (SUP) is used for modeling the fluid. The SUP method is an off-boundary approach that employs a number of point sources moved inside the body to represent the fluid response at the surface. This allows the fluid...

Method of making a wire junction encapsulating wire connector

Abstract: A solderless twist on wire connector and a method of making a solderless twist on wire junction encapsulating twist on wire connector by securing a prior art twist on wire connector in a shell to produce a wire junction encapsulating twist on wire connector that can in one operation permit the user to twist the connector to simultaneously compress the junction ends of electrical wires into low resistance electrical contact while encapsulating the junction ends of the electrical wires in a solderless substance. The process includes the method making a twist on wire connector by encapsulating a prior art twist on wire connector in a shell to produce a wire junction encapsulating twist on wire connector having a chamber for an encapsulating material. In one embodiment the twist on wire junction encapsulating twist on wire connector includes a puncturable seal and in another embodiment a second compartment for holding a mixable encapsulating materials.

Protective cap for golfers

Abstract: A protective piece of headgear including an outer cover of conventional appearance in place about and concealing an impact absorbing shell of STYROFOAM or the like. Elongate openings in the shell serve to ventilate the shell and are shaped and sized to prevent golf ball contact with the upper part of the wearer's head. Interchangeable adhesive spacer elements permit the shell to be sized to a wearer's head. Retention of the cover on the shell, either permanently or temporarily, is by a suitable adhesive.

Structural intensity in thin cylindrical shells

Abstract: A rigorous derivation of the structural intensity vector for a thin cylindrical shell is provided based on Flugge’s equations of motion and expressions for the total energy density in the shell. The shell is assumed driven by normal forces, loaded externally by a fluid, and to have no internal loss. It is confirmed that the structural intensity vector is composed of five terms, and simple physical interpretations of these terms are provided. The relationship between the structural intensity and the normal acoustic intensity is derived. The five structural intensity terms are investigated in some detail using results from a numerical experiment. The numerical model was a simply supported, point-driven cylindrical shell with external fluid loading, assumed to exist in an infinite rigid baffle. A sum over in vacuo modes was used to solve the equations of motion. The results show, in the frequency range below the ring resonance of a steel shell with h/a=0.01, that the divergence of the extensional power flow ...

Thick shell and solid finite elements with independent rotation fields

Abstract: Thick shell and solid elements presented in this work are derived from variational principles employing independent rotation fields. Both elements are built on a special hierarchical interpolation and both possess six degrees of freedom per node. Performance of the elements is evaluated on a set of problems in elastostatics. However, the formulation presented herein is also suitable for transient and non-linear problems.