scholarly journals Plastic Deformation of the Ring, Changing its Thickness in the Axial Direction in Accordance with z=cr-β, under Internal Pressure

1943 ◽  
Vol 9 (36-1) ◽  
pp. 140-145
Author(s):  
Koiti SAITO
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Axial Direction

Ratcheting assessment of corroded elbow pipes subjected to internal pressure and cyclic bending moment

2021 ◽  
pp. 030932472198989
Author(s):  
Ali Salehi ◽  
Armin Rahmatfam ◽  
Mohammad Zehsaz
Keyword(s):  
Growth Rate ◽  
Stainless Steel ◽  
Internal Pressure ◽  
Bending Moment ◽  
Axial Direction ◽  
Hoop Strain ◽  
Cyclic Bending ◽  
High Fatigue ◽  
The Impact ◽  
Cyclic Bending Moment

The present study aimed to study ratcheting strains of corroded stainless steel 304LN elbow pipes subjected to internal pressure and cyclic bending moment. To this aim, spherical and cubical shapes corrosion are applied at two depths of 1 mm and 2 mm in the critical points of elbow pipe such as symmetry sites at intrados, extrados, and crown positions. Then, a Duplex 2205 stainless steel elbow pipe is considered as an alternative to studying the impact of the pipe materials, due to its high corrosion resistance and strength, toughness, and most importantly, the high fatigue strength and other mechanical properties than stainless steel 304LN. In order to perform numerical analyzes, the hardening coefficients of the materials were calculated. The results highlight a significant relationship between the destructive effects of corrosion and the depth and shape of corrosion, so that as corrosion increases, the resulting destructive effects increases as well, also, the ratcheting strains in cubic corrosions have a higher growth rate than spherical corrosions. In addition, the growth rate of the ratcheting strains in the hoop direction is much higher across the studied sample than the axial direction. The highest growth rate of hoop strain was observed at crown and the highest growth rate of axial strains occurred at intrados position. Altogether, Duplex 2205 material has a better performance than SS 304LN.

Elastic-plastic bending of the pipeline under combined loading

2021 ◽  
pp. 372-377
Author(s):  
Виктор Миронович Варшицкий ◽  
Евгений Павлович Студёнов ◽  
Олег Александрович Козырев ◽  
Эльдар Намикович Фигаров
Keyword(s):  
Internal Pressure ◽  
Limit State ◽  
Bending Moment ◽  
Axial Direction ◽  
Longitudinal Force ◽  
Combined Loading ◽  
Dimensional Problem ◽  
Elastic Plastic ◽  
Pipeline Section ◽  
Thin Walled Pipe

Рассмотрена задача упругопластического деформирования тонкостенной трубы при комбинированном нагружении изгибающим моментом, осевой силой и внутренним давлением. Решение задачи осуществлено по разработанной методике с помощью математического пакета Matcad численным методом, основанным на деформационной теории пластичности и безмоментной теории оболочек. Для упрощения решения предложено сведение двумерной задачи к одномерной задаче о деформировании балки, материал которой имеет различные диаграммы деформирования при сжатии и растяжении в осевом направлении. Проведено сравнение с результатами численного решения двумерной задачи методом конечных элементов в упругопластической постановке. Результаты расчета по инженерной методике совпадают с точным решением с точностью, необходимой для практического применения. Полученные результаты упругопластического решения для изгибающего момента в сечении трубопровода при комбинированном нагружении позволяют уточнить известное критериальное соотношение прочности сечения трубопровода с кольцевым дефектом в сторону снижения перебраковки. Применение разработанной методики позволяет ранжировать участки трубопровода с непроектным изгибом по степени близости к предельному состоянию при комбинированном нагружении изгибающим моментом, продольным усилием и внутренним давлением. The problem of elastic plastic deformation of a thin-walled pipe under co-binned loading by bending moment, axial force and internal pressure is considered. The problem is solved by the developed method using the Matcad mathematical package by a numerical method based on the deformation theory of plasticity and the momentless theory of shells. To simplify the solution of the problem, it is proposed to reduce a twodimensional problem to a one-dimensional problem about beam deformation, the material of which has different deformation diagrams under compression and tension in the axial direction. Comparison with the results of numerical solution of the two-dimensional problem with the finite element method in the elastic plastic formulation is carried out. The obtained results of the elastic-plastic solution for the bending moment in the pipeline section under combined loading make it possible to clarify criterion ratio of the strength of the pipeline section with an annular defect in the direction of reducing the rejection. Application of the developed approach allows to rank pipeline sections with non-design bending in the steppe close to the limit state under combined loading of the pipeline with bending moment, longitudinal force and internal pressure.

Fatigue failure analysis of surface-cracked (±45°)3 filament-wound GRP pipes under internal pressure

2011 ◽  
Vol 46 (9) ◽  
pp. 1041-1050 ◽  
Author(s):  
A Samanci ◽  
N Tarakçioğlu ◽  
A Akdemir
Keyword(s):  
Internal Pressure ◽  
Surface Crack ◽  
Fatigue Behavior ◽  
Load Ratio ◽  
Axial Direction ◽  
Filament Wound ◽  
Reinforced Plastic ◽  
Filament Wound Composite ◽  
Stress Whitening ◽  
Composite Pipes

In this study, the fatigue behavior of (±45°)3 filament-wound composite pipes with a surface crack under alternating internal pressure was investigated. Glass-reinforced plastic (GRP) pipes were made of E-glass/epoxy and tested in the open-ended condition. The pipes had a surface crack with a notch–aspect ratio of a/c = 0.2 and notch-to-thickness ratios of a/t = 0.25, 0.38, or 0.50 in the axial direction. Tests were carried out in accordance with ASTM D2992. This standard offers 25 cycles/min and a load ratio of R = 0.05. Tests were performed at three different load levels: 50%, 40%, and 30% of ultimate hoop stress. Whitening, leakage, and final failure of GRP pipes were observed, and fatigue test results were presented by means of S–N curves.

Effect of Internal Pressure and Dent Depth on Strain Distribution of Pressurized Pipe Subjected to Indentation

2013 ◽  
Vol 376 ◽  
pp. 135-139 ◽  
Author(s):  
Maziar Ramezani ◽  
Thomas Rainer Neitzert
Keyword(s):  
Plastic Deformation ◽  
Internal Pressure ◽  
Cross Section ◽  
Strain Distribution ◽  
Fe Simulation ◽  
Circular Cross Section ◽  
Numerical Results ◽  
Rectangular Shape ◽  
Longitudinal Strains ◽  
Dent Depth

A dent in a pipeline is a permanent plastic deformation of the circular cross section of the pipe. This paper discusses numerical results obtained from finite element (FE) simulation of pressurized pipe subjected to radial denting by a rigid indenter. Dent produced by rectangular shape indenter is assessed and the strain distribution of the pipe is investigated. The effect of internal pressure and dent depth on the distribution of strain is also studied. The results show that the circumferential and longitudinal strains increase with increasing the internal pressure and the depth of the dent. Numerical results are compared with an empirical theoretical model in order to demonstrate the accuracy of the analysis.

Fracture Response of Girth-Welded Pipeline With Canoe Shape Embedded Crack Subjected to Large Plastic Deformation

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Lie Seng Tjhen ◽  
Zhang Yao ◽  
Zhao Hai Sheng
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Internal Pressure ◽  
Structural Integrity ◽  
Biaxial Loading ◽  
Finite Element Simulations ◽  
Critical Parameters ◽  
Large Plastic Deformation ◽  
Long Distance ◽  
Fracture Assessment

Long-distance offshore pipelines always suffer large plastic deformation during installation and operation. Accompanied by high internal pressure, potential flaws are found to initiate from the girth welds, and this brings a significant challenge to the structural integrity of the pipelines. The currently used procedures for fracture assessment of pipelines are usually stress based, which are unsuitable for application to cracked pipeline subjected to large plastic deformation. Therefore, the aim of this paper is to investigate the fracture assessment of pipeline subjected to large plastic deformation and identify and understand the critical parameters influencing the fracture responses under actual loading conditions. The evolution of crack tip opening displacement (CTOD) of a pipeline segment with an embedded canoe shape crack located in the middle of the girth weld is investigated under pure bending and biaxial loading through 3D elastic–plastic finite-element simulations. The effects of crack width, crack length, pipeline thickness, material hardening, and internal pressure on fracture response are discussed. Finally, a strain-based failure assessment diagram (FAD) is developed, and comparison between fracture assessment by BS7910:2013 and finite-element simulations concludes that the former produces conservative predictions for deep crack.

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