Showing papers on "Shell (structure) published in 1971"

Reduced integration technique in general analysis of plates and shells

Abstract: The solution of plate and shell problems by an independent specification of slopes and middle surface displacements is attractive due to its simplicity and ability of reproducing shear deformation. Unfortunately elements of this type are much too stiff when thickness is reduced. In an earlier paper a derivation of such an element was presented1 which proved very successful in ‘thick’ situations. Here a very simple extension is made which allows the element to be economically used in all situations. The improved flexibility is achieved simply by reducing the order of numerical integration applied to certain terms without sacrificing convergence properties. The process is of very wide applicability in improvement of element properties.

Improved numerical integration of thick shell finite elements

Abstract: A quadratic thick shell element derived from a three-dimensional isoparametric element was first introduced by Ahmad and co-workers in 1968. This element was noted, however, to be relatively inefficient in representing bending deformations in thin shell or thin plate applications. The present paper outlines a selective integration scheme for evaluating the stiffness matrix of the element, in which each component of the strain energy is evaluated separately using a different Gaussian integration grid for each contribution. By this procedure, the excessive bending stiffness of the element, which results from the use of me quadratic interpolation functions, is avoided. The improved performance of this element, as compared with the original thick shell element, is demonstrated by analyses of a variety of thin and thick shell problems. 1

Article of footwear

Abstract: An article of footwear is described in the form of a calf-length boot for cold weather wear. The boot assembly comprises an inner boot and an outer shell, the inner boot being formed in a boot shape from a relatively thick layer of soft, pliable foam plastic material and having sufficient dimensional rigidity to maintain an erect boot shape. The outer shell has a sole portion and an upper portion, the sole portion being of a traction material with a wear resistant surface and being peripherally joined to an upper portion of thin, pliable sheet material. The inner boot fits snugly within the outer shell to form an erect boot assembly.

Terminology for surface features in ornate ostracodes

Abstract: The surface ornament of the ostracode carapace is shown to be composed of structural elements extending into the thickness of the shell. A terminology is proposed for surface features newly revealed by scanning electron microscopy.

The Post-Buckling Problem for Thin Elastic Shells

Abstract: An asymptotic integration technique is developed to describe the post-buckling behavior of thin elastic shells. The introduction of slow space and time scales directly into the shell differential equations permits a modeling of dynamic effects and a means of accounting for finite boundaries. In most cases, quadratic nonlinear interactions dominate the dynamics and lead to hexagonal shaped patterns in the buckled shell. The form of the initial imperfection is crucial in determining the critical buckling load, as, for a given plan form, there are two separated branches in the load-displacement curve. The critical points on each branch occur at different values of the load parameter. Finally, a minimal principle is derived which exhibits the consistency of the present approach with the variational procedures of Koiter and others.

Exhaust gas manifold

Abstract: An exhaust gas manifold for an internal combustion engine in which there is provided an outer shell including an outer sleeve having a pair of end caps closing the ends thereof. An inner shell is carried within the outer shell and is formed by a plurality of slidably interfit inner sleeves which are supported in spaced relation to the outer sleeve on mounting members mounted on a second pair of end caps closing the ends of said inner shell and connected to said first pair of end caps. A plurality of inlet conduits and an outlet conduit are connected to said outer shell, and a plurality of inlet conduits and an outlet conduit are also connected to said inner shell with the conduits on said inner shell being carried in, and movable with respect to, the conduits on said outer shell.

Multi wall container and package

Abstract: The specification describes a multi-walled package of a nestable configuration that has an inner shell of thermoformed plastic material and an outer shell of paper cardboard material secured thereto and adapted to be printed thereon. The relationship of said shells being that the inner shell has a formed rim portion and a base portion each adapted to be self-sustaining or rigid, with a relatively thin flexible intermediary wall portion, and the outer shell is secured to the wall portion of the inner shell in a manner to provide structural rigidity to the wall portion and in turn the entire container. A closure having snap-in engagement with the container rim, at a number of positions is also provided.

Swimming pool construction

Abstract: The disclosure relates to a swimming pool which is made of component parts which are prefabricated and assembled at the site of the installation. A plurality of side wall members are interlocked to form a shell, the shell receiving a flexible liner which holds the water within the pool.

Dynamic interaction of a liquid with the elastic structure of a circular cylindrical container

Abstract: The present paper investigates the general case of hydroelastic coupled oscillations of a partially filled liquid container with a flexible bottom and an elastic side wall. The bottom behavior is described by the motion of a membrane or a thin, elastic, flat plate, while the sidewall is treated as a thin, elastic shell with its motion described by Donnell's shell equations. The liquid is assumed to be inviscid, homogeneous, and incompressible, the fluid motion is considered to be irrotational.

Muffler for internal combustion engines

Abstract: A muffler for a single cylinder engine comprises a shallow, elongated shell having a rear wall with an inlet port near one end of the shell and a front wall with an outlet port. A baffle plate clamped between the shell members divides the shell interior into front and rear compartments, communicated through spaced apart openings in the baffle plate. A front baffle member subdivides the front compartment into two communicated chambers, from one of which the outlet port opens and the other of which surrounds said one.

Resin-bonded expansion shell

Abstract: A resin reinforced anchor for a rock bolt consists of an expansion shell of a known type modified to mount a resin container. The resin container carries a resin and a hardenercontaining capsule therein in such a way that actuation of the expansion shell breaks the hardener-containing capsule, mixes its contents and the contents of the container, and releases the mixed contents, to adhere the expansion shell to the sides of a drill hole.

Double diaphragm brake operator improvements

Abstract: An improved air brake diaphragm chamber, having two diaphragms placed close to each other therewithin and held in position inside the chamber by a clamp band, the outer or outboard (with respect to the axle or brake) one of said diaphragms having a separate air pressure input on the outer shell of the chamber, a perforated ring spacing said two diaphragms with an air inlet connected to said perforation for feeding air between said diaphragms and means for effectively sealing the peripheral zones of said diaphragms with respect to said ring and clamp band, particularly including means preventing extrusion of the diaphragms at the connection points of the clamp band halves. The combination of the air brake diaphragm chamber with two diaphragms and the air feed means therebetween with, as a first option, an outboard spring brake unit of minimum size and, as a second option, an inboard spring brake power unit, in all cases access readily provided to both the power spring unit and the diaphragm chamber. An improved air brake diaphragm chamber, having two diaphragms placed close to each other therewithin and held in position inside the chamber by a clamp band, the outer or outboard (with respect to the axle or brake) one of said diaphragms having a separate air pressure input on the outer shell of the chamber, the inboard one of said diaphragms having a central opening or perforation therethrough, the brake actuating rod in operative connection with said diaphragm and connected thereto, said brake operating rod hollow whereby fluid pressure may be input between said diaphragm through said brake operating rod, and means for effectively sealing the peripheral zones of said diaphragms with respect to said clamp band, particularly including means preventing extrusion of the diaphragms at the connection points of the clamp bands halves. An improved air brake diaphragm chamber, having a single diaphragm therewithin held in position inside the chamber by a clamp band, and means for effectively sealing the peripheral zones of said diaphragm with respect to said clamp band, particularly including means preventing extrusion of the diaphragm at the connection points of the clamp band halves.

Energy absorbing bumper assembly

Abstract: An energy absorbing bumper assembly including a mounting means defined by a metal plate adapted for attachment to a vehicle and an elongated shell made of elastomeric material disposed adjacent or forwardly of the mounting plate. A pair of urethane energy absorbing blocks are disposed adjacent the centerline of the bumper assembly between the frontal face of the shell and the mounting plate. A second pair of energy absorbing urethane blocks are disposed adjacent the ends of the assembly between the frontal face of the shell and the mounting plate. The shell is an integral member which includes a horizontal web having a first section at each end of the shell adjacent the outwardly disposed urethane blocks and extending longitudinally of the shell and engaging the mounting plate. The web includes a pair of second sections each of which extends from one of the first sections toward the longitudinal centerline of the shell but with the second sections splaced from the mounting plate. More particularly, each of the second sections tapers away from the mounting plate as it extends longitudinally toward the centerline of the shell. Thus, the horizontal web is varyingly spaced from the mounting plate. The blocks define a bumper means for absorbing a first quantity of energy resulting from specified impacts and the web defines another bumper means for absorbing a different quantity of energy resulting from impacts other than the specified impacts. An alternative embodiment is included wherein the web is replaced with an energy absorbing elastomeric material having a different energy absorbing capacity than the first and second pairs of blocks.

Shipping container for radioactive material

Abstract: The body means of the shipping container includes an inner shell means and an outer shell means spaced outwardly of the inner shell means, radiation shielding material being disposed within the space between the inner and outer shell means. The inner shell means defines a radioactive material receiving cavity therewithin having a cross-sectional configuration defining three sides, adjacent ones of the sides joining one another to define three apexes to thereby provide maximum capacity with a minimum size and weight container.

Floating power plant

Abstract: A floating power plant is housed in a generally spherical double-walled shell. The shell and its contents form part of a compound pendulum whose center of mass is located below the metacenter of the sphere and which has a natural frequency substantially below that of the prevailing wave frequency of the water. Consequently, the power plant is supported upright in the water and does not rock in response to the wave motion of the water.

On the Parametric Resonance of a Cylindrical Shell Subjected to a Periodic Axial Load

Abstract: The dynamic stability of thin‐walled circular cylindrical shell is studied for the case of periodic axial load. In computing the internal membrane stress induced by the axial pressures, the cylinder is assumed to act as a longitudinal bar. The internal membrane stress is computed by considering the shell to be a longitudinal rod with axial inertia terms included. Hence, the internal axial coordinate as well as with time and to include the resonances of the cylinder acting as a longitudinal rod. The problem under study is to determine the stability of the flexural motions of the shell oscillating about this inextensional mode. The shell motion is represented by Donnell's equations. A study of the solutions of these equations reveals parametric resonance of the well‐known type and a second parametric resonance which appears to be new. The latter includes the combination resonance between two modes having the same modal pattern, and also between two modes having different modal patterns. In particular, this includes combination resonance between two transverse modes having a different number of axial half waves. This result is believed to be new and is considered the principal result of the study being described. It is only obtained when axial inertia is included in computing the axial membrane stress. It is found that combination resonance does not exist between modes having a different number of circumferential waves. The two modes must have the same number of axial waves. An estimate is given for the width of the unstable regions, and numerical results are presented. The extension to a shell having the effects of rotatory inertia and shear deformation is briefly discussed.

Window or door

Abstract: The invention relates to a window or door with window wing or door wing and window case or door case made of plastics sections, the hinges comprising parts integrally connected with the wing and case, respectively, namely a hinge shell and an axially movable hinge pin, in which the improvement resides in that a plurality of hinges is arranged along the sides, preferably along all sides of the window or door, comprising hinge pins guided in sleeves inserted in bores in the wing section or case section, respectively, which hinge pins by means of an electric drive may selectively be pushed out into the respective shell-forming bore of the corresponding case section or corresponding wing section and retracted from said bore, whereby, when the hinge pins are pushed out on only one side of the window or door while at the same time the hinge pins on all other sides of the window or door are retracted, a swinging axis is formed, whereas, when on more than one side of the window or door the hinge pins are pushed out, locks are formed. With this arrangement an excellent connection between the sections is achieved.

On the Transmission of Sound through Finite Closed Shells: Statistical Energy Analysis, Modal Coupling, and Nonresonant Transmission

Abstract: An investigation of sound transmission into small enclosures considers the effects of acoustically induced coupling between shell modes. The level of cavity reactance is examined. The noise reductions for a closed cylinder and a rectangular parallelopiped enclosure (with a single flexible panel) placed in reverberant acoustic fields are computed and experimentally checked. The transmission by resonant and nonresonant shell modes is examined, especially in relation to the statistical‐energy‐analysis approach. The nature of the predominance of one type of transmission over the other is considered in relation to shell and cavity configurations and structural damping levels.

Orientation of empty pelecypod shells and shell fragments in quiet water

Abstract: Participation in man-in-the-sea experiments Tektite I and II permitted an examination of the orientation of pelecypod shells and shell fragments on sediment unaffected by waves or currents. Whether on vegetated or unvegetated unrippled sand or on solid coral, the particles lie predominantly with concave sides up. This orientation occurs both for open articulated empty valves and for isolated disarticulated valves. The degrees of orientation differs with shell size; the smaller shells are less preferentially oriented concave-up than are the larger shells. The concave-up orientation results from the activity of predators and scavengers, from bioturbation, or from a combination of the two mechanisms. An experiment that exposed nearly 1200 shells to 40 days of bioturbation demonstrated that disturbance by organisms is an effective agent for producing a dominantly concave-up orientation. Shell size and shell shape are significant factors in bioturbational rotation. In general, the tendency to be rotated to a concave-up position increases with increasing shell size to the point where shells are too large to be readily overturned by most organisms. The percent of concave-up shells also depends on the angle of balance of the shell; shells rotated by bioturbation tend to behave like loaded dice. Shells that became buried during the experiment howed a more random orientation than did those exposed on the surface after 40 days. The orientation of shells in quiet water differs markedly from those orientations produced under most conditions of waves or currents. Although concave-up assemblages can be produced by deposition from turbidity currents or from the transport of shells across small ripples, analysis of orientation as it relates to shell size and shape may provide a means of identifying specific depositional mechanisms or conditions.

Analysis of Horizontally Curved Box Girder Bridges

Abstract: A stiffness method for the analysis of simply supported curved girder bridges with horizontal sector plates and vertical cylindrical shell elements is outlined. Stiffness coefficients of sector plates are presented herein whereas stiffness coefficients of shell elements are based on Hoff’s solution of Donnell’s equations. A numerical example illustrating the application of the method is shown. Some interesting results, particularly those with respect to the effect of radius of curvature, were obtained. A comparison is made between the results of a curved twin box girder bridge obtained by the proposed method and Tung’s method.