scholarly journals Joint Kinematics and Sealing Capacity Assessment of Ductile Iron Pipes under Abrupt Transverse Ground Movements

2021 ◽  
Author(s):  
Xiaogang Qin ◽  
Yu Wang ◽  
Cuiwei Fu
Keyword(s):  
Ductile Iron ◽  
Joint Kinematics ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Joint Rotation ◽  
Joint Kinematic ◽  
Ground Movements ◽  
Sealing Capacity ◽  
Axial Translation ◽  
Kinematic Behaviour

Joint kinematic behaviour, i.e., joint rotation and axial translation, can partially help pipelines to accommodate abrupt ground movements, and cause leaking if joint service limit is exceeded, even without any structural failure. Kinematic behaviour of bell-spigot jointed ductile iron (DI) pipes and its influence on joint sealing capacity under abrupt transverse ground movements are investigated in this study. Firstly, a beam-on-spring finite element analysis on joint kinematics of DI pipes is conducted, in which different fault-pipe crossing positions are implemented. Based on simulated results, a modified joint kinematic solution incorporating pipe deflection and joint shear force under different fault-pipe crossing positions is proposed. Then, a Monte Carlo simulation (MCS)-based reliability assessment procedure for joint sealing capacity is developed. Sensitivity analysis is subsequently conducted to investigate the effects of uncertainties associated with initial axial translation, soil properties, and crossing positions on the joint sealing capacity, and the effects of different deterministic solutions are compared. The proposed method allows engineers to effectively evaluate how the joint sealing capacity of DI pipes changes with consideration of uncertainties when abrupt transverse ground movements are encountered.

Elastic-Plastic J-Estimation for Circumferentially Cracked Pipes Under Combined Mechanical and Thermal Loadings

2013 ◽  
Author(s):  
Chang-Young Oh ◽  
Yun-Jae Kim ◽  
R. A. Ainsworth
Keyword(s):  
Finite Element ◽  
Thermal Gradient ◽  
Order Effects ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Defect Assessment ◽  
Failure Assessment ◽  
Two Parameters ◽  
J Estimation

This paper addresses load order effects on elastic-plastic J estimation under combined mechanical and thermal loads for circumferentially cracked pipes. The load order effects, for various thermal gradient types and mechanical loading, are evaluated for a range of magnitudes of the loadings, crack sizes and material hardening. Variations of elastic-plastic J obtained by finite element analysis are compared with existing and proposed methods for use with the R6 defect assessment procedure. The load order effects are presented on the R6 failure assessment diagram (FAD) by calculating the two parameters Kr and Lr from the finite element results. It is shown that there are significant load order effects at large secondary stress cases but these are successfully treated by simplified methods proposed for use with R6.

Integral Mean of Yield Concept Applied to Thermal Hot Spots: Validation of a Level 2 Damage Assessment Method

2018 ◽  
Author(s):  
Henry Kwok ◽  
Simon Yuen ◽  
Jorge Penso
Keyword(s):  
Hot Spots ◽  
Damage Assessment ◽  
Hot Spot ◽  
Load Capacity ◽  
Assessment Method ◽  
Pressure Vessels ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Level 3 ◽  
Level 2

The overall framework for a Level 2 assessment of local thermal hot spot in pressure vessels was first developed by Seshadri [1]. The assessment procedure invokes the concept of integral mean of yield and the concept on a reference volume to determine the reduction of load capacity caused by hot spot damage. This paper investigates the accuracy of this assessment by comparing the results of the Level 2 assessment with a Level 3 assessment (inelastic finite element analysis). Three examples with varying pressure component and hot spot sizes are considered. The comparison yielded a low variance between the Level 2 and Level 3 assessments with the Level 2 assessment being more conservative.

scholarly journals Sealing Performance Analysis of an End Fitting for Marine Unbonded Flexible Pipes Based on Hydraulic-Thermal Finite Element Modeling

Energies ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 2198 ◽  
Author(s):  
Liping Tang ◽  
Wei He ◽  
Xiaohua Zhu ◽  
Yunlai Zhou
Keyword(s):  
Finite Element ◽  
Fluid Pressure ◽  
Temperature Fields ◽  
Effect Of Temperature ◽  
Fe Model ◽  
Element Analysis ◽  
Sealing Capacity ◽  
Sealing Performance ◽  
Metal Seal ◽  
Essential Components

End fittings are essential components in marine flexible pipe systems, performing the two main functions of connecting and sealing. To investigate the sealing principle and the influence of the temperature on the sealing performance, a hydraulic-thermal finite element (FE) model for the end fitting sealing structure was developed. The sealing mechanism of the end fitting was revealed by simulating the sealing behavior under the pressure penetration criteria. To investigate the effect of temperature, the sealing behavior of the sealing ring under different temperature fields was analyzed and discussed. The results showed that the contact pressure of path 1 (i.e., metal-to-polymer seal) was 31.7 MPa, which was much lower than that of path 2 (metal-to-metal seal) at 195.6 MPa. It was indicated that the sealing capacities were different for the two leak paths, and that the sealing performance of the metal-to-polymer interface had more complicated characteristics. Results also showed that the finite element analysis can be used in conjunction with pressure penetration criteria to evaluate the sealing capacity. According to the model, when the fluid pressures are 20 and 30 MPa, no leakage occurs in the sealing structure, while the sealing structure fails at the fluid pressure of 40 MPa. In addition, it was shown that temperature plays a significant role in the thermal deformation of a sealing structure under a temperature field and that an appropriately high temperature can increase the sealing capacity.

UK Research Programme on Residual Stresses: Progress to Date

2007 ◽  
Author(s):  
S. K. Bate ◽  
A. P. Warren ◽  
C. T. Watson ◽  
P. Hurrell ◽  
J. A. Francis
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Research Programme ◽  
Assessment Procedure ◽  
Engineering Structures ◽  
Element Analysis ◽  
Simplifying Assumptions ◽  
Modelling Techniques

A long-term UK research programme on residual stresses was launched in 2004. It involves Rolls-Royce plc and Serco Assurance, and is supported by UK industry and academia. The programme is aimed at progressing the understanding of weld residual stresses and the implementation of finite element simulation and residual stress measurement for assessing the integrity of engineering structures. Following on from this, the intention is then to develop improved guidance on residual stress modelling techniques. In the first two years finite element activities have addressed heat source representation, simplified modelling (e.g. 2D v 3D, bead lumping), material hardening models, high temperature behaviour and phase transformations. It is recognized that simplifying assumptions have to be made in order to reduce the computational run-time and modelling complexity, especially for multi-pass welds. The effects of these assumptions on the determined stresses have been considered by carrying out finite element analyses of welded mock-ups. The welded mock-ups have been developed to provide measured residual stress data which are necessary to validate the modelling techniques that have been developed. These activities have been used to support the development of guidelines on the use finite element analysis to predict residual stresses in welded components. These guidelines will be incorporated in the next issue of the British Energy R6 defect assessment procedure.

A deep retaining structure in till and sand. Part II: Performance and analysis

1983 ◽  
Vol 20 (1) ◽  
pp. 131-140 ◽  
Author(s):  
Z. Eisenstein ◽  
L. V. Medeiros
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Case History ◽  
Lateral Pressure ◽  
Stress Strain ◽  
Element Analysis ◽  
Transit System ◽  
Ground Movements ◽  
Retaining Structure ◽  
Analytical Results

The problem of magnitude and distribution of lateral pressure acting on a deep retaining structure supporting an excavation in till and sand is studied by an approach integrating field measurements from a case history with a finite element analysis. Also studied are ground movements associated with the excavation. The finite element analysis is based on stress path dependent testing of the soils involved.The case history is the behaviour of a deep supported wall of the underground Churchill Square Station of the recently built line of the Light Rail Transit System in Edmonton. A tangent pile wall, 17 m deep, has been placed through glacial till to underlying sands. The site has been instrumented to record displacements of the wall and of the surrounding ground as well as the loads carried by the lateral supports.A finite element analysis employing several stress–strain models was used to simulate the excavation and its sequence, the placement of lateral support, and the differential stiffness of the structural components and of the surrounding soil. Special attention has been given to the effect of different stress–strain models of soils, with a particular focus on the influence of stress paths typical for the studied structure.Agreement between the field and analytical results for displacements is accepted as a criterion of validity of the analytical results of stresses, where direct in situ stress measurements are difficult to obtain and interpret. Of special importance is the calculated lateral pressure against the wall and its relation to the stiffness of the wall and to the magnitude of associated ground movements. The calculated lateral pressure has been found to differ significantly from the semiempirical design pressure diagrams used in practice.The soil stress–strain model found to describe the field behaviour most closely has been derived from test results obtained using a plane strain apparatus. Keywords: deep supported excavation, displacement, lateral pressure, field measurement, finite element analysis.

Plastic Collapse Assessment Procedure for Vessel With Local Thin Area Simultaneously Subjected to Internal Pressure and External Bending Moment

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Shinji Konosu ◽  
Norihiko Mukaimachi
Keyword(s):  
Internal Pressure ◽  
Pressure Ratio ◽  
Bending Moment ◽  
Outer Diameter ◽  
Assessment Procedure ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Tension And Compression ◽  
And Storage ◽  
Moment Ratio Diagram

Assessment of the local thin area should be undertaken for both tension and compression bending. In this paper, simplified reference stresses for a flaw in a cylinder are proposed. By using these results, a newly developed p-M (internal pressure ratio and external bending moment ratio) diagram which can evaluate the collapse condition for pressure equipment such as vessels, piping, and storage tanks with a local thin area simultaneously subjected to internal pressure p and external bending moment M due to earthquake, etc., is proposed. The p-M line is verified by comparison with the finite element analysis results and the numerous results of experiment for a cylinder with a volumetric flaw obtained through the reference literatures. It was clarified that the differences in collapse limit between the p-M line and DNV guideline under both internal pressure and compression moment became evident where the outer diameter/wall thickness of a cylinder is large and the yield ratio of the material is small.

scholarly journals Sex, Age and Stature Affects Neck Biomechanical Responses in Frontal and Rear Impacts Assessed Using Finite Element Head and Neck Models

2021 ◽  
Vol 9 ◽  
Author(s):  
M. A Corrales ◽  
D. S Cronin
Keyword(s):  
Finite Element ◽  
Intervertebral Disc ◽  
Injury Risk ◽  
Muscle Activation ◽  
Facet Joint ◽  
Epidemiological Data ◽  
Joint Kinematics ◽  
Joint Rotation ◽  
Head Kinematics ◽  
Rear Impacts

The increased incidence of injury demonstrated in epidemiological data for the elderly population, and females compared to males, has not been fully understood in the context of the biomechanical response to impact. A contributing factor to these differences in injury risk could be the variation in geometry between young and aged persons and between males and females. In this study, a new methodology, coupling a CAD and a repositioning software, was developed to reposture an existing Finite element neck while retaining a high level of mesh quality. A 5th percentile female aged neck model (F0575YO) and a 50th percentile male aged neck model (M5075YO) were developed from existing young (F0526YO and M5026YO) neck models (Global Human Body Models Consortium v5.1). The aged neck models included an increased cervical lordosis and an increase in the facet joint angles, as reported in the literature. The young and the aged models were simulated in frontal (2, 8, and 15 g) and rear (3, 7, and 10 g) impacts. The responses were compared using head and relative facet joint kinematics, and nominal intervertebral disc shear strain. In general, the aged models predicted higher tissue deformations, although the head kinematics were similar for all models. In the frontal impact, only the M5075YO model predicted hard tissue failure, attributed to the combined effect of the more anteriorly located head with age, when compared to the M5026YO, and greater neck length relative to the female models. In the rear impacts, the F0575YO model predicted higher relative facet joint shear compared to the F0526YO, and higher relative facet joint rotation and nominal intervertebral disc strain compared to the M5075YO. When comparing the male models, the relative facet joint kinematics predicted by the M5026YO and M5075YO were similar. The contrast in response between the male and female models in the rear impacts was attributed to the higher lordosis and facet angle in females compared to males. Epidemiological data reported that females were more likely to sustain Whiplash Associated Disorders in rear impacts compared to males, and that injury risk increases with age, in agreement with the findings in the present study. This study demonstrated that, although the increased lordosis and facet angle did not affect the head kinematics, changes at the tissue level were considerable (e.g., 26% higher relative facet shear in the female neck compared to the male, for rear impact) and relatable to the epidemiology. Future work will investigate tissue damage and failure through the incorporation of aged material properties and muscle activation.

scholarly journals A New Multi-Level Assessment Procedure for Corroded Line Pipe

2000 ◽  
Author(s):  
Duane S. Cronin ◽  
Roy J. Pick
Keyword(s):  
Three Dimensional ◽  
Strain Curve ◽  
Tensile Tests ◽  
Assessment Method ◽  
Uniaxial Tensile ◽  
Assessment Procedure ◽  
Element Analysis ◽  
Line Pipe ◽  
Experimental Database ◽  
Multi Level

A new assessment method to predict the failure pressure of corrosion defects in line pipe has been developed. Comparison to an experimental database shows that this new assessment procedure has advantages over existing techniques. The implementation of this method is proposed in a multi-level assessment procedure. The assessment levels are organized in terms of increasing complexity, with Level I being a lower bound solution and requiring only the maximum defect depth. The new assessment method requires detailed corrosion geometry measurements and is proposed as a Level II. Three dimensional elastic-plastic finite element analysis is proposed for the Level III. These methods assume the true stress-strain curve of the material is known, which can be determined from uniaxial tensile tests. When these material properties are unknown, the currently accepted codes are suggested for defect evaluation.

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