Stresses in Curved, Circular Thin-Wall Tubes

1963 ◽  
Vol 30 (1) ◽  
pp. 134-135
Author(s):  
E. A. Utecht
Keyword(s):  
Thin Wall ◽  
Bending Moments ◽  
Circular Tubes ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending

Curves are presented which give stress intensification factors for curved, thin-walled circular tubes under various combinations of in-plane and out-of-plane bending moments.

A characteristic type of instability in the large deflexions of elastic plates III. Curved rectangular plates in axial compression

1954 ◽  
Vol 222 (1148) ◽  
pp. 44-59 ◽  
Keyword(s):  
Axial Compression ◽  
Rectangular Plates ◽  
Bending Moments ◽  
Elastic Plates ◽  
Characteristic Type ◽  
Circular Tubes ◽  
Axis Parallel ◽  
Post Buckling ◽  
Thin Walled ◽  
The Stability

The analysis of part I is extended to deal with the case of free-edged rectangular plates having an initial curvature about an axis parallel to one pair of opposite edges and loaded by distributed bending moments applied to the straight edges and compressive forces applied to the curved edges. In particular, the stability and post-buckling behaviour of such plates subjected to the compressive forces alone is studied. The axially symmetrical buckling of thin-walled circular tubes in axial compression is also considered. Experimental plates are found to buckle at loads rather lower than those predicted.

Stress and flexibility factors for multi-mitred pipe bends subjected to internal pressure combined with external loadings

1972 ◽  
Vol 7 (2) ◽  
pp. 97-108 ◽  
Author(s):  
M P Bond ◽  
R Kitching
Keyword(s):  
Internal Pressure ◽  
Large Diameter ◽  
Pipe Bend ◽  
Bending Tests ◽  
Bending Load ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending ◽  
Internal Pressures ◽  
Stress Patterns

The stress analysis of a multi-mitred pipe bend when subjected to an internal pressure and a simultaneous in-plane or out-of-plane bending load has been developed. Stress patterns and flexibility factors calculated by this analysis are compared with experimental results from a large-diameter, thin-walled, three-weld, 90° multi-mitred bend which was subjected to in-plane bending tests at various internal pressures.

Bend Flexibility Factors of Piping Elbows and Piping Elbows With Trunnion Attachments Using the Boundary Element Method

2009 ◽  
Author(s):  
Manuel Martinez ◽  
Johane Bracamonte ◽  
Marco Gonzalez
Keyword(s):  
Boundary Element Method ◽  
Numerical Method ◽  
Bending Moment ◽  
Piping System ◽  
Thin Walled Structures ◽  
Out Of Plane ◽  
Thin Walled ◽  
Plane Bending ◽  
Flexibility Factor ◽  
Element Method

Flexibility Factor is an important parameter for the design of piping system related to oil, gas and power industry. Elbows give a great flexibility to piping system, but where a trunnion is attached to an elbow in order to support vertical pipe sections, the piping flexibility is affected. Generally, determination of elbow flexibility factors has been performed by engineering codes such as ASME B31.3 or ASME B31.8, or using the Finite Element Method (FEM) and Finite Difference Method (FDM). In this work, bend flexibility factors for 3D models of piping elbows and piping elbows with trunnion attachments using the Boundary Element Method (BEM) are calculated. The BEM is a relatively new numerical method for this kind of analysis, for which only the surface of the problem needs to be discretized into elements reducing the dimensionality of the problem. This paper shows the simulation of 9 elbows with commercially available geometries and 29 geometries of elbows with trunnion attachments, 10 of them using commercial elbow dimensions, with applied in-plane and out-of-plane bending moments. Structured meshes are used for all surfaces, except the contact surface of elbow-trunnion joints, and no welded joints are simulated. The results show smaller values of flexibility factors of elbow and elbow–trunnion attachments in all loading cases if are compared to ASME B31.3 or correlations obtained from other works. The results also indicate that flexibility factor for elbow-trunnion attachment subjected to in-plane bending moment is greater than flexibility factor for out-of plane bending moment. Accuracy of BEM’s results were not good when flexibility characteristic values are lesser than 0.300, which confirm the problems of this numerical method with very thin-walled structures. The method of limit element could be used as tool of alternative analysis for the design of made high-pitched system, when the problem with very thin-walled structures is fixed.

Stress Concentrations in DT/X Square-to-Square and Square-to-Round Tubular Joints

1994 ◽  
Vol 116 (2) ◽  
pp. 49-55 ◽  
Author(s):  
A. K. Soh ◽  
C. K. Soh
Keyword(s):  
Stress Concentration ◽  
Bending Moment ◽  
Bending Moments ◽  
Axial Loads ◽  
Stress Concentrations ◽  
Tubular Joints ◽  
Out Of Plane ◽  
Concentration Factors ◽  
Plane Bending ◽  
Stress Concentration Factors

A parametric stress analysis of DT/X square-to-square and square-to-round tubular joints subjected to axial loads, in-plane, and out-of-plane bending moments has been performed using the finite element technique in order to provide a sound basis for using such sections in the design of complex structures. The results of this analysis are presented as a set of equations expressing the stress concentration factor as a function of the relevant geometric parameters for various loading conditions. A comparison is made between the results obtained for square-to-square and square-to-round tubular joints and those obtained for round-to-round tubular joints by other researchers. In general, the stress concentration factors for square-to-square tubular joints are the highest, followed by those of the corresponding round-to-round joints, with those of the corresponding square-to-round joints the lowest when the joints are subject to axial loads. In the case of in-plane bending moment, the stress concentration factors for square-to-square joints are generally still the highest, but followed by those of the corresponding square-to-round joints, with those of the corresponding round-to-round joints the lowest. However, the stress concentration factors for the three types of joint are comparable when they are subject to out-of-plane bending moments.

Shakedown Boundary of a 90–Degree Back–to–Back Pipe Bend Subjected to Steady Internal Pressures and Cyclic Out–of–Plane Bending Moments

2014 ◽  
Author(s):  
Hany F. Abdalla
Keyword(s):  
Internal Pressure ◽  
Bending Moment ◽  
Bending Moments ◽  
Pipe Bend ◽  
Structure Comparison ◽  
Out Of Plane ◽  
Plane Bending ◽  
Shakedown Limit ◽  
Elastic Shakedown ◽  
Internal Pressures

Ninety degree back–to–back pipe bends are extensively utilized within piping networks of modern nuclear submarines and modern turbofan aero–engines where space limitation is considered a supreme concern. According the author’s knowledge, no shakedown analysis exists for such structure based on experimental data. In the current research, the pipe bend setup analyzed is subjected to a spectrum of steady internal pressures and cyclic out–of–plane bending moments. A previously developed direct non–cyclic simplified technique, for determining elastic shakedown limit loads, is utilized to generate the elastic shakedown boundary of the analyzed structure. Comparison with the elastic shakedown boundary of the same structure, but subjected to cyclic in–plane bending moments revealed a higher shakedown boundary for the out–of–plane bending loading configuration with a maximum bending moment ratio of 1.4 within the low steady internal pressure spectrum. The ratio decreases towards the medium to high internal pressure spectrum. The simplified technique outcomes showed excellent correlation with the results of full elastic–plastic cyclic loading finite element simulations.

Exact Matching Condition at a Joint of Thin-Walled Box Beams Under Out-of-Plane Bending and Torsion

2012 ◽  
Vol 79 (5) ◽  
Author(s):  
Soomin Choi ◽  
Gang-Won Jang ◽  
Yoon Young Kim
Keyword(s):  
Beam Theory ◽  
Matching Condition ◽  
Higher Order ◽  
Transformation Matrix ◽  
Exact Matching ◽  
Box Beam ◽  
Out Of Plane ◽  
Box Beams ◽  
Thin Walled ◽  
Plane Bending

To take into account the flexibility resulting from sectional deformations of a thin-walled box beam, higher-order beam theories considering warping and distortional degrees of freedom (DOF) in addition to the Timoshenko kinematic degrees have been developed. The objective of this study is to derive the exact matching condition consistent with a 5-DOF higher-order beam theory at a joint of thin-walled box beams under out-of-plane bending and torsion. Here we use bending deflection, bending/shear rotation, torsional rotation, warping, and distortion as the kinematic variables. Because the theory involves warping and distortion that do not produce any force/moment resultant, the joint matching condition cannot be obtained just by using the typical three equilibrium conditions. This difficulty poses considerable challenges because all elements of the 5×5 transformation matrix relating the field variables of one beam to those in another beam should be determined. The main contributions of the investigation are to propose additional necessary conditions to determine the matrix and to derive it exactly. The validity of the derived joint matching transformation matrix is demonstrated by showing good agreement between the shell finite element results and those obtained by the present box beam analysis in various angle box beams.

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