Study on Limit Load of Orthotropic Cylindrical Pipe Under Different Combined Load Conditions

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Min Xu ◽  
Jian-bin Wen ◽  
Yu-jie Zhao ◽  
Chang-Yu Zhou ◽  
Xiao-hua He
Keyword(s):  
Yield Strength ◽  
Internal Pressure ◽  
Axial Force ◽  
Shear Force ◽  
Bending Moment ◽  
Limit Load ◽  
Cylindrical Pipe ◽  
Load Combination ◽  
Combined Loads ◽  
Torsion Moment

Abstract In engineering, many pressure pipes are made of steels with good plasticity, which are subject to internal pressure, axial force, shear force, bending moment, torsion moment or their combined loads. The plastic limit load is an important indicator of the load capacity of pressure pipe. According to Hill yield function, the theoretical solutions of limit load of orthotropic cylindrical pipe under various combined loads under internal pressure, axial force, shear force, torsion moment, and bending moment have been derived on the basis of elastic perfectly plastic constitutive model. The effects of radial stress on different combined limit loads of cylindrical pipe are explored and these results show that the radial stress should be considered about the limit load calculation especially for thick-walled cylindrical pipe. The interactions of various load combination are analyzed in detail and drawn with the interaction curves. For isotropic cylindrical pipe, the limit load increases with the yield strength. For the orthotropic cylindrical pipe, the limit loads of cylindrical pipe under axial force, bending moment, shear force, and torsion moment without internal pressure are only related to the axial yield strength. The limit bending moment is mainly dependent on the axial yield strength when internal pressure is lower, while the impact of the circumferential yield strength of orthotropic cylindrical pipe is obvious when internal pressure is some higher. When the axial yield strength of orthotropic cylindrical pipe is the same, the circumferential yield strength can enhance the limit axial load, limit torsion moment, and limit shear load. Under the different load conditions including internal pressure, bending moment, axial force, shear force, and torsion moment or their combined loads, the relation of limit bending moment with yield strength ratio is diverse, which is decide by the load combination, the circumferential yield strength, and the axial yield strength.

Limit Load Solutions of the Orthotropic Thick-Walled Pipe Subjected to Internal Pressure, Bending Moment and Torsion Moment

2019 ◽  
Author(s):  
Min Xu ◽  
Yujie Zhao ◽  
Binbin Zhou ◽  
Xiaohua He ◽  
Changyu Zhou
Keyword(s):  
Analytical Solution ◽  
Yield Strength ◽  
Internal Pressure ◽  
Yield Criterion ◽  
Bending Moment ◽  
Limit Load ◽  
Pure Bending ◽  
Pure Torsion ◽  
Torsion Moment ◽  
The Difference

Abstract Based on the Hill yield criterion, the analytical solutions of the limit load of orthotropic thick-walled pipes under pure internal pressure, bending moment and torsion are given respectively. The simplified Mises analytical solution and finite element results of limit load for isotropic thick-walled pipe are obtained. The solution verifies the reliability of the analytical solution. The paper discusses the difference of limit load of isotropic and orthotropic pipes under the conditions of pure internal pressure, pure bending moment and pure torsion moment. It is concluded that the influence of material anisotropy on the limit load is significant. The limit load of pipe under pure internal pressure is mainly determined by circumferential yield strength, pure bending is only related to axial yield strength and pure torsion moment is related to the yield strength in the 45° direction and radial yield strength.

The Limit Load Interactions of the Brazed Aluminum Plate-Fin Heat Exchanger Header Under Combined Piping Loads

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Wei Wang ◽  
Liang Chen ◽  
Caidong Guo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Heat Exchanger ◽  
Axial Force ◽  
Shear Force ◽  
Bending Moment ◽  
Limit Load ◽  
Force Component ◽  
Element Analysis ◽  
Interaction Curves

In order to investigate the strength design problem of the brazed aluminum plate-fin heat exchanger header under complex external piping loads, the limit load interactions of the header under combined piping loads are studied in this paper. To establish the limit piping load interaction curves, nonlinear finite element analysis assuming the elastic perfectly plastic material model is performed by using the commercial finite element analysis software ANSYS and multiple piping load combinations, which are the combination of orthogonal bending moment components, torque component-shear force component, bending moment component-axial force component, compound bending moment-axial force component, and torque component-compound shear force, of the header with six opening ratios ranging from 0.5 to 1 are explored. The results of the interaction diagrams show that the feasible combined piping load zone of the header derived from the interaction curves can be simplified as a triangular zone determined by the individual limit piping load components safely and the simplified feasible zone is suggested to be used for establishing a simplified safety assessment method for the header under combined piping loads.

The Effect of D/T on the Load Interaction Behavior of a Plain Pipe

2004 ◽  
Vol 126 (4) ◽  
pp. 518-522 ◽  
Author(s):  
Amran Bin Ayob
Keyword(s):  
Internal Pressure ◽  
Effective Stress ◽  
Axial Force ◽  
General Trend ◽  
Bending Moment ◽  
Design Codes ◽  
Yield Behavior ◽  
Combined Loads ◽  
Interaction Behavior ◽  
Von Mises

The objective of the study is to determine the effect of diameter/thickness (D/T) ratio on the interaction of axial force, bending moment, torsion and internal pressure in plain pipes. The Tresca and von Mises criteria are used to determine the first yield behavior of pipes when subjected to combined loads. The results show that for certain load combinations, the load interaction behavior is affected by D/T ratio and some load interaction relations change with a load dominance. The general trend is an increase in effective stress as D/T is increased. Most design codes show slightly conservative pipe design.

Shakedown and Limit Analysis of Kinematic Hardening Piping Elbows Under Internal Pressure and Bending Moments

2021 ◽  
Author(s):  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
Yield Strength ◽  
Internal Pressure ◽  
Limit Analysis ◽  
Kinematic Hardening ◽  
Limit Load ◽  
Bending Moments ◽  
Plastic Limit ◽  
Plastic Limit Load ◽  
Interaction Curves ◽  
Shakedown Limit

Abstract In this paper, the Stress Compensation Method (SCM) adopting an elastic-perfectly-plastic (EPP) material is further extended to account for limited kinematic hardening (KH) material model based on the extended Melan's static shakedown theorem using a two-surface model defined by two hardening parameters, namely the initial yield strength and the ultimate yield strength. Numerical analysis of a cylindrical pipe is performed to validate the outcomes of the extended SCM. The results agree well with ones from literature. Then the extended SCM is applied to the shakedown and limit analysis of KH piping elbows subjected to internal pressure and cyclic bending moments. Various loading combinations are investigated to generate the shakedown limit and the plastic limit load interaction curves. The effects of material hardening, elbow angle and loading conditions on the shakedown limit and the plastic limit load interaction curves are presented and analysed. The present method is incorporated in the commercial finite element simulation software and can be considered as a general computational tool for shakedown analysis of KH engineering structures. The obtained results provide a useful information for the structural design and integrity assessment of practical piping elbows.

Buckling Analysis of Tubular Strings in Horizontal Wells

SPE Journal ◽  
2014 ◽  
Vol 20 (02) ◽  
pp. 405-416 ◽  
Author(s):  
Wenjun Huang ◽  
Deli Gao ◽  
Fengwu Liu
Keyword(s):  
Boundary Conditions ◽  
Axial Force ◽  
Shear Force ◽  
Virtual Work ◽  
Bending Moment ◽  
Horizontal Wells ◽  
Comprehensive Description ◽  
New Model ◽  
First Category ◽  
Second Category

Summary A new buckling equation in horizontal wells is derived on the basis of the general bending and twisting theory of rods. The boundary conditions of a long tubular string are divided into two categories: the sum of the virtual work of bending moment and shear force at the ends of tubular strings is equal to zero, and the sum of the virtual work of bending moment and shear force at the ends is not equal to zero. Buckling solutions under different boundary conditions are obtained by solving the new buckling model. For the boundary conditions of the first category, the buckling solutions are identical with previous results. For the boundary conditions of the second category, the buckling solutions are different from the results under the boundary conditions of the first category. The results indicate that buckling behaviors depend on both the axial force and the boundary conditions. Compared with previous results, buckling solutions of the new model provide a more comprehensive description of tubular-buckling behaviors.

The Assessment of Locally Thinned Areas Subject to a Hoop Stress and an Axial Stress: Background to the Guidance Given in Annex G of BS 7910:2013

2019 ◽  
Author(s):  
Andrew Cosham ◽  
Robert Andrews
Keyword(s):  
Internal Pressure ◽  
Axial Force ◽  
Hoop Stress ◽  
Axial Stress ◽  
Bending Moment ◽  
Full Scale ◽  
Plane Bending

Abstract Annex G Assessment of locally thinned areas (LTAs) in BS 7910:2013 is applicable to LTAs in cylinder, a bend and a sphere or vessel end. It can be used to assess the longitudinally-orientated LTA in a cylinder subject to a hoop stress and a circumferentially-orientated LTA in a cylinder subject to an axial stress (due to axial force, in-plane bending moment and internal pressure), and also to assess an LTA subject to a hoop stress and an axial stress. An outline of the origins of Annex G is given. A comparison with full-scale burst tests of pipes or vessels containing LTAs subject to a hoop stress and an axial stress is presented. It is demonstrated that the method in G.4.3 Hoop stress and axial stress is conservative.

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