Determination of local stresses in a cylindrical shell loaded over a circular area

1989 ◽  
Vol 29 (6) ◽  
pp. 915-919
Author(s):  
B. V. Nerubailo ◽  
I. F. Obraztsov ◽  
V. P. Ol'shanskii
Keyword(s):  
Cylindrical Shell ◽  
Circular Area ◽  
Local Stresses

Overcoming radiotelemetry bias in habitat-selection studies

1999 ◽  
Vol 77 (8) ◽  
pp. 1175-1184 ◽  
Author(s):  
W James Rettie ◽  
Philip D McLoughlin
Keyword(s):  
Habitat Selection ◽  
Patch Size ◽  
Habitat Patch ◽  
Habitat Types ◽  
Species Determination ◽  
Circular Area ◽  
Habitat Mosaics ◽  
Study Techniques ◽  
Habitat Patch Size

For many species, determination of habitat selection is based on habitat-use data obtained through radiotelemetry. Recent papers pertaining to study techniques have largely ignored the effect of habitat-dependent bias in the performance of radiotelemetry systems. Such biases cannot be overcome by increasing radiotelemetry precision, excluding data, or increasing sample sizes, as the biases are centred around data that are missing or that contain habitat-dependent errors in location. The problem is best addressed at the data-analysis stage through the use of geographic information systems. We used Monte Carlo simulations to assess the effect of habitat-dependent bias in radiotelemetry studies on the assessment of habitat selection. We looked at the effects of habitat-patch size, level of telemetry signal inhibition, level of habitat co-occurrence, and selection pattern. We demonstrated that regarding use as the composition of habitat types within a circular area around each telemetry location can help to overcome the inaccurate assessment of habitat-selection patterns that biased data produce. The size of the circular area best able to overcome the bias is related to habitat patch size and to the level of association between two or more habitat types. Furthermore, we argue that the characteristics of habitat mosaics selected by animals can and should be studied in this way.

scholarly journals A Semi-Analytical Solution for Elastic Analysis of Rotating Thick Cylindrical Shells with Variable Thickness Using Disk Form Multilayers

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Mohammad Zamani Nejad ◽  
Mehdi Jabbari ◽  
Mehdi Ghannad
Keyword(s):  
Cylindrical Shell ◽  
Analytical Solution ◽  
Differential Equations ◽  
Variable Thickness ◽  
Deformation Theory ◽  
Shear Deformation Theory ◽  
First Order ◽  
Thick Cylinder ◽  
Good Agreement

Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the cylinder is divided intondisks,nsets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM) is also presented and good agreement was found.

Determination method of dynamic distorted scaling laws and applicable structure size intervals of a rotating thin-wall short cylindrical shell

2014 ◽  
Vol 229 (5) ◽  
pp. 806-817 ◽  
Author(s):  
Z Luo ◽  
YP Zhu ◽  
XY Zhao ◽  
DY Wang
Keyword(s):  
Cylindrical Shell ◽  
Scaling Laws ◽  
Good Accuracy ◽  
Scaling Law ◽  
Thin Wall ◽  
Determination Method ◽  
Governing Equations ◽  
7050 Aluminum Alloy ◽  
Boundary Functions

This study investigates the applicability of distortion models for predicting dynamic characteristics of a rotating thin-wall short cylindrical shell. The significance of this study is that it provides a necessary scaling law, applicable structure size intervals, and its boundary functions, which can guide the design of distortion models. Sensitivity analysis and governing equations are employed to establish the scaling law between the model and the prototype. Then a commonly used 7050 aluminum alloy cylindrical shell is analyzed as a prototype. The determination of applicable structure size intervals is discussed, and the boundary functions of the applicable structure size intervals are investigated. The applicability of the scaling law and the applicable intervals of rotating thin-wall short cylindrical shell are verified numerically. The results indicate that distortion models that satisfy the structure size applicable intervals can predict the characteristics of the prototype with good accuracy.

Local Flexibility of Cylindrical Shells and Pipes at the Support

1993 ◽  
Vol 115 (4) ◽  
pp. 359-363
Author(s):  
L. S. Ong
Keyword(s):  
Cylindrical Shell ◽  
Close Agreement ◽  
Shell Theory ◽  
Theoretical Data ◽  
Parametric Equation ◽  
Local Flexibility ◽  
Support Force ◽  
Geometric Variables ◽  
Applied Displacement

This article presents a parametric study for the determination of the flexibility and stiffness of a cylindrical shell at its support location. The parametric equation incorporates the geometric variables of both cylindrical shell and support; namely, the shell radius, thickness, and length, and the support width and embracing angle. A mathematical model has been devised to provide the theoretical data of flexibilities for establishing the parametric equation. The model is based on a contact stress formulation and uses a cylindrical shell theory. The validity and accuracy of the proposed parametric equation has been checked against available experimental results obtained from literature. There is close agreement between the two. The present study and results should be useful to designers who wish to determine the induced support force (or displacement) due to applied displacement (or force) at the support.

On the Determination of the Centers of Twist and of Shear for Cylindrical Shell Beams

1972 ◽  
Vol 39 (4) ◽  
pp. 1098-1102 ◽  
Author(s):  
E. Reissner ◽  
W. T. Tsai
Keyword(s):  
Cylindrical Shell ◽  
Cross Section ◽  
Flat Plates ◽  
Influence Coefficients ◽  
Special Cases ◽  
Box Beams ◽  
Circular Cylindrical Shells ◽  
Definition Of ◽  
Open Cross Section

We consider the problem on the basis of a definition of the centers of shear and of twist in terms of influence coefficients for end-loaded cantilever beams. We determine the influence coefficients approximately by combining the Saint Venant torsion and flexure solutions with an appropriate version of the principle of minimum complementary energy. We apply this method, considering the beam as a cylindrical shell. We find among other things a formula for closed-cross-section shells which includes as special cases the strength-of-materials formula for open-cross-section shells, as well as a formula for variable-thickness flat plates. Problems of particular theoretical interest for which solutions are given concern rectangular box beams and circular cylindrical shells with circumferentially varying properties.

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