Corrigendum to: When is a sum of annihilator ideals an annihilator ideal?

In this corrigendum, we correct the statement and proof of Lemma 3.2, revise the proofs of Lemma 3.3 and Theorem 3.5, retract Proposition 3.10 and correct several typographical errors.     

An approximate solution to the problem of a circular cylindrical shell with a circular hole subjected to an arbitrary self-equilibrated edge loading

Summary In this investigation, we shall use Donnell's equation of shallow circular cylindrical shell to obtain an approximate solution for stresses in an infinitely long circular cylindrical shell with a circular hole about which there acts a self-equilibrated load. To satisfy the edge conditions, we first shall expand the appropriate solutions of the differential equation into series containing powers, products of powers and logarithm, of the characteristic parameter ₀ defined in (1). We then shall represent the unknown coefficients of the solutions in similar series including new constants which depend only on the material property and the type of loading. We determine the new unknown constants through simple algebraic equations. In conclusion, we shall present two examples for symmetric and anti-symmetric loadings, including expressions which illustrate their accuracy, and expressions for stress concentration.

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Übersicht Es wird eine Näherungslösung für die Spannungen in einer unendlich ausgedehnten kreiszylindrischen Schale mit einem kreisförmigen Loch mit Hilfe der Donnel-Gleichung für flache Schalen angegeben. Der Lochrand wird durch eine im Gleichgewicht befindliche Last beansprucht. Zur Erfüllung der Randbedingungen werden die Eigenlösungen der Differentialgleichung in Reihen entwickelt, die neben Potenzen auch Produkte von Potenzen und logarithmischen Gliedern des charakteristischen Parameters ₀ enthalten, der in Gl. (1) definiert ist. Die unbekannten Koeffizienten der Lösungen werden in entsprechender Weise durch Reihen dargestellt. Sie enthalten neue Konstante, die nur noch von den Materialeigenschaften und der Belastungsart abhängen. Diese Konstanten werden durch einfache algebraische Gleichungen bestimmt. Zwei Beispiele für symmetrische und antimetrische Belastung werden durchgerechnet, wobei die Spannungskonzentration und die Genauigkeit des Verfahrens erkennbar werden.

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The author is indebted to Dr. E. F. Casebeer for invaluable editorial suggestions.     

Restrictions on nonlinear constitutive equations for elastic shells

Constitutive equations for the resultant forces and moments applied to a shell-like body necessarily couple the influences of the shell geometry and the constitutive nature of the three-dimensional material from which the shell is constructed. Consequently, even when the nonlinear constitutive equation of the three-dimensional material is known, the complicated influence of the shell geometry on the constitutive response of the shell is not known. The main objective of this paper is to develop restrictions on the constitutive equations of nonlinear elastic shells which ensure that exact solutions of the shell equations are consistent with exact nonlinear solutions of the three-dimensional equations for homogeneous deformations. Since these restrictions are nonlinear in nature they provide valuable general theoretical guidance for specific constitutive assumptions about the coupling of material and geometric properties of shells. Examples of the linear theories of a plate and a spherical shell are considered.     

A linear theory of straight elastic rods

This paper is based on the work of Green & Laws who have given a general thermodynamical theory of rods which is valid for any material. Here, starting with the general non-linear theory of elastic rods, we derive a linear theory allowing for thermal effects. The resulting free energy as a quadratic function of kinematic variables is restricted by certain symmetry conditions. The basic equations then separate into four groups, two for flexure, one for torsion and one for extension of the rod with temperature effects occurring only in the latter group. Wave propagation along an infinite rod is considered. There are two wave speeds for each type of flexure, two for torsion and three for isothermal extension and all wave speeds depend on the wave length.     

The effect of a transverse shear acting on the edge of a circular cutout in a simply supported circular cylindrical shell

Summary First, the solution to the problem of a simply supported circular cylindrical shell (without a cutout) subjected to a circumferential segmental line load at the middle of the shell is derived. Next, the negatives of the stress resultants and stress couples at a given radius ₀, obtained from this solution, are combined with a transverse shear force to form the edge conditions for a circular cylindrical shell containing a circular cutout with radius ₀. The desired solution is finally obtained by superposing the above two solutions. The convergence of the series, obtained in the first part, is improved for the complete region near and on the segmental line load. Numerical results are presented.

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Übersicht Es wird zunächst die Lösung für die Spannungsverteilung in einer einfach gelagerten kreiszylindrischen Schale ohne Ausschnitt angegeben. Die Schale wird durch eine Linienlast längs eines Umfangs in der Mitte der Schale belastet. Die hierfür erhaltenen Kräfte und Momente für einen gegebenen Radius ₀ werden dann mit einer Quer-Schubkraft kombiniert, um die Randbedingungen für eine kreiszylindrische Schale mit rundem Ausschnitt vom Radius ₀ zu erhalten. Die gewünschte Lösung wird schließlich durch Überlagerung der beiden Teillösungen erhalten. Die Konvergenz der dabei auftretenden Reihenentwicklungen wird für den Bereich der Belastungslinie verbessert. Numerische Ergebnisse werden angegeben.

     

Physically nonlinear and related approximate theories of elasticity,and their invariance properties

The existing developments of physically nonlinear elasticity have several shortcomings. With the aim of remedying these deficiencies, a number of approximate theories of elasticity are discussed in the present paper and, in particular, a theory of physically nonlinear elasticity is systematically developed. More specifically, stress-strain relations for anisotropic physically nonlinear materials are derived. The method of Casey & Naghdi [1] is then applied to obtain properly invariant results. This method involves the use of auxiliary motions obtained by removing from any given motion the translation and rotation at any one particle, called a pivot. The auxiliary motions represent the original motions in the approximate theory. The connection between the transformation of fields under a change of pivot and invariance requirements associated with the auxiliary motions is investigated.     

A Direct theory of viscous fluid flow in channels

This paper deals with an Eulerian formulation of the theory of directed fluid sheets appropriate for incompressible, linear viscous fluid flow in channels with arbitrary shapes for their major boundaries which may be moving or fixed. Special cases of the theory are applied to a number of two-dimensional fluid flow problems and these solutions are in general discussed for unsteady flow. Specific applications include fluid flow in a channel whose boundaries are symmetric with respect to a middle plane in the channel, subjected to time-dependent pressure gradient at one end; and to lubrication problems in a general shaped channel when one of the channel walls is a fixed plane while the other is moving with a constant velocity. Flow of a viscous fluid with a free surface over a fixed boundary is also discussed.Dedicated to J. L. Ericksen on the occasion of his Sixtieth Birthday     

Stress distribution around large holes in flat plates

Summary Employing a special case of a new method, the solution for the problem of a rectangular flat plate with a central large circular cutout subject to some transverse load and/or moment is derived. This is achieved with the use of certain eigenfunctions generated by sets of circular line loadings of the plate. Numerical results are presented for special cases.

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Übersicht Die Spannungsverteilung für eine rechteckige Platte mit einem großen kreisförmigen Ausschnitt in der Mitte unter der Einwirkung von Querlasten und/oder Momenten wird mit Hilfe des Spezialfalles einer neuen Methode berechnet. Dabei werden Eigenfunktionen verwendet, die durch kreisförmige Linienlasten auf der Platte erzeugt werden. Einige numerische Ergebnisse werden angegeben.

     

On the formulation of contact problems of shells and plates

The equations of motion in terms of resultants and the constitutive equations in the theory of shells and plates are ordinarily derived from the three-dimensional equations relative to an interior surface, often taken to be the middle surface in the reference configuration of the shell-like body. This usual formulation is not, in general, applicable to contact problems of shells for which one of the major surfaces, e.g., the upper surface, is specified as the reference surface. The present paper is concerned with the transformation relations between the relevant variables (and hence also the response functions) of the traditional formulation and one which can be obtained relative to one of the major surfaces. Our derivations, carried out both from the three-dimensional equations and by a direct approach, utilize only the conservation laws and the field equations without recourse to constitutive equations. Hence, the results are applicable to any shell-like medium and their validity is not limited to elastic shells alone.