A modified reference strain method for engineering critical assessment of reeled pipelines

Jia, Pengyu; Jing, Hongyang; Han, Yongdian; Zhao, Lei

doi:10.1016/j.ijmecsci.2015.11.003

Cited by 14 publications

(4 citation statements)

References 16 publications

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“…Liu et al, 2012;Nourpanah and Taheri, 2010;Chiodo and Ruggieri, 2010;Parise et al, 2015;Østby, 2005)). Others were derived analytically from the original form of reference stress method proposed by Ainsworth (1984) with limited FE validations (e.g Budden, 2006;Budden and Ainsworth, 2012;Smith, 2012;Pisarski et al, 2014;Jia et al, 2016)). Some of these solutions predict the J-integral only, thus the CTOD was calculated by the following relationship:…”

Section: Comparison With Existing Crack Driving Force Solutionsmentioning

confidence: 99%

Fracture response of X65 pipes containing circumferential flaws in the presence of Lüders plateau

Wang

et al. 2019

International Journal of Solids and Structures

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A yield discontinuity or Lüders plateau can be observed in tensile tests conducted on seamless pipe manufactured to API 5L X65 strength grade steel. Such material behaviour is associated with strain localisation which can significantly affect the fracture behaviour of X65 steel pipe subjected to plastic strain. This study considers the Lüders plateau, using the so-called "updown-up" (UDU) constitutive model, in finite element (FE) analyses of seamless X65 pipes containing circumferential surface-breaking cracks and subjected to axial plastic straining. The softening modulus of UDU model was found to significantly affect the simulated evolution of plasticity, crack driving force and crack-tip fields of the cracked pipe. The FE analysis results were validated against the full-scale pipe test data. It was found that by correctly selecting the softening modulus, a suitable level of accuracy and conservatism was obtained by using an UDU model in FE analyses for assessing fracture response of flawed pipes which show Lüders plateau behaviour. In contrast, the existing stress-and strain-based fracture assessment solutions generally underestimate the crack driving force in the Lüders plateau phase.

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Section: Comparison With Existing Crack Driving Force Solutionsmentioning

confidence: 99%

Fracture response of X65 pipes containing circumferential flaws in the presence of Lüders plateau

Wang

et al. 2019

International Journal of Solids and Structures

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“…Failure assessment diagram (FAD) [8,9] is a kind of assessment method which is related with the fracture toughness and fracture parameters, e.g. stress intensity factor (SIF) K and J-integral.…”

Section: Introductionmentioning

confidence: 99%

Constraint modified time dependent failure assessment diagram (TDFAD) based on C(t)-A2(t) theory for creep crack

Dai

Liu

Qin

et al. 2020

International Journal of Mechanical Sciences

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Due to the potential influence of constraint effect on failure assessment, a link is needed to bridge the constraint effect characterized by higher order term asymptotic solution and time dependent failure assessment diagram (TDFAD). In this paper, a modification method for creep toughness incorporating C(t)-A2(t) theory is proposed based on Nikbin-Smith-Webster model. The relation between Q-term and A2(t)-term is also presented for creep crack. Results show that the creep toughness can be influenced by constraint parameter remarkably. A modified TDFAD is proposed based on C(t)-A2(t) solution. Based on the creep data of 316H stainless steel and various compact tension specimens, the modified TDFAD curves considering constraint effect characterized with A2(t)-term is presented and discussed, which indicates the important role of constraint effect on the assessment boundary of TDFAD. The research given in this paper can provide an alternative method in which the constraint effect can be included in TDFAD under high temperature.

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“…However, in some situations, the pipes is subjected to displacement-or strain-controlled loading deforming into the plastic regime [130], such as in the reeling installation [110]. In this case, strain-based approach is preferably employed for the fracture assessment [131][132][133].…”

Section: Validation Studymentioning

confidence: 99%

“…Jayadevan et al [37] and Østby et al [38] investigated the fracture responses of homogeneous pipes with a surface crack based on 3-D FE analysis, and it is noted that the CTOD varies linearly with the global strain. Jia et al [131][132][133] proposed a modified engineering critical assessment method for the metallic pipelines containing a circumferential surface crack [133] and a deeplyembedded crack [132], respectively. The variation tendency of CTOD with the global strain for the welded clad pipes with an external surface crack was studied by Zhang et al [134], where the proposed assessment equation is only suited to a specific pipe configuration.…”

Section: Validation Studymentioning

confidence: 99%

Fracture assessment of cracked clad pipelines with weld misalignment

Zhao¹

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With increasing demand of recoverable corrosive hydrocarbons, metallurgically bonded double walled pipelines, referred to as clad pipelines, are widely used to transport the corrosive natural resources. The clad pipelines consist of a carbon steel outer pipe providing the load capacity and a corrosion resistant alloy liner protecting the carbon steel outer pipe from corrosion. The pipeline is constructed by joining one end of the pipe to the other end by girth welding process, and potential cracks are usually detected to initiate from the welding region. Furthermore, weld misalignment, centerline offset misalignment or angular misalignment, is also invariably introduced into the pipeline during the welding process, which further reduces the integrity of the pipes due to the introduction of local bending stress. Therefore, it's crucial to investigate the fracture responses of cracked clad pipelines with weld misalignment. Although BS7910-Amendment 1 [1] has proposed a fracture assessment equation for misaligned structures, the equation actually uses fracture parameters of aligned configurations to assess the corresponding parameters of misaligned ones based on superposition principle, resulting in an over-conservative prediction. Therefore, the fracture analysis for cracked configurations with weld misalignment needs to be investigated in detail. In this study, a finite element (FE) mesh generator is developed to serve for the cracked clad pipelines with weld misalignment, and a small-scale experimental test is carried out to verify the validity of the mesh generator. Based on the mesh generator, extensive 3-D FE analysis is performed to determine the stress intensity factors (SIFs) of aligned and misaligned welded joints. The corresponding SIF equations are proposed using multiple regression analysis, which consider the effect of weld misalignment on the SIFs directly, not by the superposition principle. Then, the fracture responses for oval-shaped clad pipelines with a surface crack are analyzed, and an equivalent J-estimation procedure is built up. Finally, engineering critical assessment is conducted to investigate the effect of weld misalignment on the cracked clad pipelines, and a fracture assessment framework covering the commonly used pipe configurations is established to predict the fracture parameters.

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A modified reference strain method for engineering critical assessment of reeled pipelines

Cited by 14 publications

References 16 publications

Fracture response of X65 pipes containing circumferential flaws in the presence of Lüders plateau

Fracture response of X65 pipes containing circumferential flaws in the presence of Lüders plateau

Constraint modified time dependent failure assessment diagram (TDFAD) based on C(t)-A2(t) theory for creep crack

Fracture assessment of cracked clad pipelines with weld misalignment

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