Methods of determining the stress-strain state and fracture toughness of gas- and oil-line pipe (survey)

Kaminskii, A. A.; Bastun, V. N.

doi:10.1007/bf02700676

Cited by 4 publications

(2 citation statements)

References 19 publications

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“…A nondestructive method that can be generalized to the elastic domain is that employing plastic indicators [5,18,39,40], which are attached to a structure and deform together with it. Testing the method against models and full-scale structures shows that the error of estimating the SSS is from 10 to 12% [18].…”

Section: Stress-strain Analysismentioning

confidence: 99%

Applied Problems in the Mechanics of Strain Hardening of Structural Metallic Materials

Bastun

Kaminskii

2005

Int Appl Mech

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Some applied problems of the mechanics of strain-hardening processes in metallic materials are considered. To solve these problems, the concept of loading surface, which separates the elastic and elastoplastic domains in the stress space, is used. Strain-hardening models are analyzed. For a wide range of steels and alloys, the most commonly used hypothesis of isotropic-and-kinematic hardening is experimentally justified Keywords: applied problems, strain hardening, metallic materials, loading surface Introduction. While manufactured, many metal members experience elastoplastic deformation. Examples of processes that induce such deformation are plastic working, hydraulic shaping of pressurized shells, expansion of welded large-diameter pipes, and autofrettage [7, 33, 37, 52, 54, 86, etc.]. Elastoplastic strains may also occur in members of space-rocket and aviation structures, which are characterized by a small margin of safety, during operation and in off-normal situations, under overloads.The elastoplastic deformation of polycrystallic materials, which include structural metals, is accompanied by structural transformations such as shattering and rotation of grains, formation of shear planes when parts of a crystal slide over each other, and preferred orientations (texture). The random orientation of crystals results in residual microstresses [36,51].Dislocation theory regards elastoplastic deformation as displacement of dislocations and increase in their density. The resistance of crystalline materials to deformation is determined by the mobility and density of dislocations. The stress fields of dislocations have a significant blocking effect on the hardening of materials [52].Some of the above-mentioned effects (shattering of grains, change of density and mobility of dislocations) lead to isotropic hardening, i.e., to approximately equal increase in resistance to deformation in different directions, while rotation of grains, preferred orientations and fibration, and residual microstresses make the hardening process directional. This results in anisotropy of mechanical properties. Its degree is determined by the contribution of one mechanism or another. In the case of unstable states, elastoplastic deformation is additionally accompanied by a change in the phase composition of the material. The physical fundamentals of strain hardening of metals are outlined in [7, 52, 57, 58, 64, etc.].Thus, elastoplastic deformation leads to unequal (in different directions) change in strength characteristics (yield points and ultimate strength). The change of the yield point was investigated most adequately in the case of a uniaxial stress state. Decrease in resistance to deformation due to reversal of the sign of the load is known as the Bauschinger effect, which is the simplest manifestation of strain hardening. The degree of strain hardening is determined by the ratio of yield points in two opposite directions, which is a measure of the Bauschinger effect.In the case of a complex stress state, strain hardening is judged fr...

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Section: Stress-strain Analysismentioning

confidence: 99%

Applied Problems in the Mechanics of Strain Hardening of Structural Metallic Materials

Bastun

Kaminskii

2005

Int Appl Mech

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“…For example, pipelines are used as integral parts in different streams in the oil and gas industry; they are utilised to extract products from a well, for multi-phase separation in the upstream, transportation and storage in the midstream and refinement in the downstream. With the energy needs of the industry set to increase in the coming years [1], pipeline sustainability and integrity have become key focus areas in the past decade due to numerous pipeline ruptures that have led to income and environmental losses, property destruction and even death [2]. Pipeline failures result in significant environmental impacts even in low-risk scenarios where pipelines operate outside the vicinity of human activities.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of guided wave tomography for pipelines via improved transduction and signal deconvolution

Caffoor¹

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I would first and foremost like to thank my supervisor, Assistant Professor Fan Zheng, for his guidance and invaluable discussions. Our weekly meetings have always been insightful, and of all his qualities that I hope to emulate, the two that stand out the most would be his patience and kindness. This thesis would not have been possible without him.Special mentions go out to my peers and seniors in the NDT group at Nanyang Technological University of Singapore (NTU). My utmost appreciation in particular to Dr Yu Xudong, Dr Zuo Peng and Captain Danylo Liesevych. They have helped explain fundamental theory of Guided Wave during my first year and have always made themselves available to orientate me to new equipment or methods of simulation. Their friendship will always be cherished greatly. I would also like to thank Dr Chen Jian, for introducing me to COMSOL and for teaching me methods of modelling PZTs, and Dr Rao Jing for providing reconstruction of defects from our on-site inspections at Jurong Island. This Ph.D would not have been possible without the support from my industry sponsor, Lloyd's Register (LR) and the Economic Development Board of Singapore (EDB). My sincere gratitude to Dr Vynx Lim, the Lead Pipeline Specialist from LR, who has been a haven for discussions on pipelines, whose encouragement and advice have been invaluable and whose experience in the industry is something I hope to attain in my lifetime.Special thanks to the Energy Market Authority of Singapore (EMA) for providing the grant for doing the research on gas pipeline monitoring and SembCorp Gas Ltd for opening their doors to the team from NTU for the monthly on-site inspections.V Finally, and most importantly of all, I would like to thank my parents, Mr. Hamzah Caffoor and Mdm Mariam Homod, for their support and encouragement throughout my Ph.D. I would be remised not to mention my Parents-in-law, Mr. Farid Khan and Mdm.Naeemah Diab, who have supported our little family during the final lap in the Ph.D as well. I am forever indebted to their love and support.To my best friend and wife, Raeesah Khan, my son, Raees Khan Caffoor, and my daughter, Ayla Khan Caffoor, I dedicate this thesis. It will always be us against the world. Love you guys. VI ContentsCONTENTS.

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Analysis of Repaired Cracks With Bonded Composite Wrap in Pipes Under Bending

Achour

Albedah

Benyahia

et al. 2016

Journal of Pressure Vessel Technology

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Composite materials have been used to structurally repair piping and other facilities for many years. However, the original use of composite materials was for repairing corroded pipelines where the intent was to restore strength to the damaged section of the pipeline. In addition to repairing corrosion, composite materials have successfully been used to repair dents, wrinkle bends, induction bends, and pipe fittings including elbows and tees as well as repair of offshore risers. In this study, the behavior of circumferential through cracks in repaired pipe with bonded composite wrap subjected to bending moment is investigated using three-dimensional finite-element analysis. The stress intensity factor (SIF) is utilized as a fracture criterion. The effects of the mechanical and geometrical properties of the adhesive on the variation of the SIF at the crack front were also analyzed. The obtained results show that the presence of the bonded composite repair significantly reduces the SIF, which can improve the residual lifespan of the pipe. Meanwhile, the SIF is also reduced as the elastic and the geometrical wrap properties are improved, particularly when the Young's modulus of the adhesive and the wrap thickness are increased.

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Methods of determining the stress-strain state and fracture toughness of gas- and oil-line pipe (survey)

Cited by 4 publications

References 19 publications

Applied Problems in the Mechanics of Strain Hardening of Structural Metallic Materials

Applied Problems in the Mechanics of Strain Hardening of Structural Metallic Materials

Enhancement of guided wave tomography for pipelines via improved transduction and signal deconvolution

Analysis of Repaired Cracks With Bonded Composite Wrap in Pipes Under Bending

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