Analysis of a Circular Cylindrical Shell Perforated by a Large Number of Radial Holes

1967 ◽  
Vol 89 (3) ◽  
pp. 325-332
Author(s):  
J. B. Mahoney ◽  
V. L. Salerno

The present paper considers a circular cylindrical shell perforated by many radially aligned circular holes that pierce its surface in repeating rectangular patterns (Fig. 1). Eight “effective” stiffness coefficients are developed for this configuration by comparing the elastic strain energy density for an idealized perforated cylindrical shell element (shown in Fig. 2) to the energy density of an orthotropic cylindrical shell element. General equations for the perforated shell element are obtained by utilizing these eight “effective” stiffness coefficients. The general set of equations is then reduced to the usual three partial differential equations in terms of the u, v, and w-displacements. This set of displacement equations is solved for two specific cases; the first case is the rotationally symmetric one where the shell is considered completely perforated; the second case is that of a partially perforated shell. Here a portion of a perforated shell is joined with a portion of an isotropic cylindrical shell along two edges, where θ is constant (see Fig. 4).

2005 ◽  
Vol 73 (4) ◽  
pp. 709-711
Author(s):  
James G. Simmonds

The techniques used by Koiter in 1968 to derive a simplified set of linear equilibrium equations for an elastically isotropic circular cylindrical shell in terms of displacements and the associated pointwise error estimate engendered in Love’s uncoupled strain-energy density are here extended to derive analogous simplified equilibrium equations and an error estimate for elastically isotropic cylindrical shells of arbitrary closed cross section.


2008 ◽  
Vol 08 (03) ◽  
pp. 465-485 ◽  
Author(s):  
YUH-CHYUN TZENG ◽  
CHING-CHURN CHERN

Presented herein is a formulation for the buckling of a cylindrical shell subjected to external loads using an infinitesimal shell element defined in a convenient coordinate system. The governing equation in terms of the radial deflection is derived for the element by adopting an operator. The eighth order partial differential equation derived can be applied for cylindrical shells with various boundary conditions. For illustration, simply supported cylindrical shells subjected to axial compressive forces are studied using either a one-variable or a two-variable shape function. The critical stresses obtained for the buckling of cylindrical shells are compared with those by the finite element program SAP2000. The critical stress of the cylindrical shell is similar to that of the column, in that the critical stress decreases as the thickness ratio (the ratio of R/h) or the slenderness ratio increases. Good agreement has been obtained for most of the comparative cases, while the finite element results appear to be slightly higher for some cases.


2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.


1980 ◽  
Vol 102 (1) ◽  
pp. 8-22 ◽  
Author(s):  
A. M. Hecht ◽  
H. Yeh ◽  
S. M. K. Chung

Collapse of arteries subjected to a band of hydrostatic pressure of finite length is analyzed. The vessel is treated as a long, thin, linearly elastic, orthotropic cylindrical shell, homogeneous in composition, and with negligible radial stresses. Blood in the vessel is treated as a Newtonian fluid and the Reynolds number is of order 1. Results are obtained for effects of the following factors on arterial collapse: intraluminal pressure, length of the pressure band, elastic properties of the vessel, initial stress both longitudinally and circumferentially, blood flow Reynolds number, compressibility, and wall thickness to radius ratio. It is found that the predominant parameter influencing vessel collapse for the intermediate range of vessel size and blood flow Reynolds numbers studied is the preconstricted intraluminal pressure. For pressure bands less than about 10 vessel radii the collapse pressure increases sharply with increasing intraluminal pressure. Initial axial prestress is found to be highly stabilizing for small band lengths. The effects of fluid flow are found to be small for pressure bands of less than 100 vessel radii. No dramatic orthotropic vessel behavior is apparent. The analysis shows that any reduction in intraluminal pressure, such as that produced by an upstream obstruction, will significantly lower the required collapse pressure. Medical implications of this analysis to Legg-Perthes disease are discussed.


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