Improved Folias Factor and Burst Pressure Models for Corroded Pipelines

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Bipul Chandra Mondal ◽  
Ashutosh Sutra Dhar
Keyword(s):  
Finite Element ◽  
Reduction Factor ◽  
Fe Analysis ◽  
Thick Wall ◽  
Burst Pressure ◽  
Test Results ◽  
Fitness For Purpose ◽  
Defect Depth ◽  
New Model ◽  
Burst Test

Burst pressure models are used for the fitness-for-purpose assessment of energy pipelines. Existing burst pressure models for corroded pipelines are unable to predict the pipe capacity correctly. In this paper, an improved burst pressure model is developed for corroded pipelines considering the burst pressure of flawless pipes and a reduction factor due to corrosion separately. The equation for the burst pressure of flawless pipe is revised based on the theory of the thick wall cylinder. A new model for the Folias factor is proposed for calculating the reduction factor. The new model for the Folias factor incorporates the depth of corrosion defect, whereas the existing models do not account for the effect of the defect depth. The authors' earlier work revealed that the Folias factor depends on the depth of defect. The proposed burst model reasonably predicts the burst pressures obtained from finite element (FE) analysis conducted in this study and the burst test results available in the published literature.

Finite-Element Evaluation of Burst Pressure Models for Corroded Pipelines

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Bipul Chandra Mondal ◽  
Ashutosh Sutra Dhar
Keyword(s):  
Finite Element ◽  
Three Dimensional ◽  
Reduction Factor ◽  
Burst Pressure ◽  
Design Codes ◽  
Pressure Reduction ◽  
Test Results ◽  
Laboratory Test Results ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

Codes/standards have been developed to calculate accurately the burst pressure for corroded pipelines. Five burst pressure models are evaluated in this paper using three-dimensional finite-element (FE) analysis. The finite-element models are validated using burst test results available in the literature. The design codes/standards are found to calculate variable burst pressures with respect to the finite-element calculations and the laboratory test results. The variability in the calculated burst pressures is attributed to the use of different flow stresses for the material and different burst pressure reduction factors for the corroded geometry. The Folias factor is considered as the major parameter contributing to the burst pressure reduction factor. Three different equations are currently used to calculate the Folias factor in the design codes that are expressed in terms of l2/(Dt). However, the finite-element evaluation presented here reveals that the Folias factor also depends on other parameters such as the defect depth.

Ultimate Behavior of Single Shear Bolted Connections with Thin-Walled Aluminum Alloys(6061-T6)

2012 ◽  
Vol 446-449 ◽  
pp. 3441-3445 ◽  
Author(s):  
Tae Soo Kim ◽  
Yong Hyun Jo ◽  
Seung Hun Kim ◽  
Yong Taeg Lee
Keyword(s):  
Finite Element ◽  
Ultimate Strength ◽  
Plane Deformation ◽  
Free Edge ◽  
Fe Analysis ◽  
Test Results ◽  
Bolted Connections ◽  
Element Analysis ◽  
Out Of Plane ◽  
Single Shear

The purpose of this study is to investigate the ultimate behaviors of aluminum alloy bolted connections assembled with four bolts. Specimens for single shear bolted connections were tested and finite element analysis based on this test results was conducted. The validity of finite element(FE) analysis for predicting the structural behaviors such as ultimate strength, fracture mode and curling(out-of-plane deformation) occurrence was verified through the comparisons between test results and FE analysis results. It is known that the curling resulted in sudden strength drop. Moreover, FE models with free edge and restrained out-of-plane deformation for curled specimens are analyzed additionally, therefore, the influence of curling on the ultimate strength; strength reduction ratio is estimated.

Fracture Mode Prediction Method for Pipe With Wall-Thinning by Using the History Data of Strain Ratio

2008 ◽  
Author(s):  
Irwan Herman ◽  
Toshiyuki Meshii
Keyword(s):  
Fracture Mode ◽  
Prediction Method ◽  
Strain Ratio ◽  
Burst Pressure ◽  
Test Results ◽  
Element Analysis ◽  
Load Increment ◽  
History Data ◽  
Burst Test ◽  
Wall Thinning

In this study, based on the burst test results of pipes with wall-thinning, we have investigated the effect of flaw length δz and pipe size (mean radius Rm) on the burst pressure by using finite element analysis (FEA). Then, the history data of strain ratio εz/εθ along the load increment was used for the fracture mode prediction. Moreover, effect of the wall thickness at the flaw portion t1 on the fracture mode was investigated. Finally, fracture mode prediction method for pipes with wall-thinning was proposed.

The Modeling Study on Kinematic Interface Joints Based on Accordant Displacement Method

2010 ◽  
Vol 29-32 ◽  
pp. 48-53
Author(s):  
Xue Qian Chen ◽  
Qiang Du ◽  
Xiao Juan Chen
Keyword(s):  
Finite Element ◽  
Solid State Laser ◽  
Fe Analysis ◽  
Ambient Vibration ◽  
Fe Model ◽  
Mean Square ◽  
Test Results ◽  
Contact Form ◽  
Displacement Method ◽  
Reflector System

The kinematic interface joints are widely used in reflector systems of the high-power solid-state laser facilities. In order to get better finite element(FE) analysis results of reflector systems, it is important to model the joints exactly. The accordant displacement method is used for modeling the joints according to the contact form of joints. The FE model of the reflector system is built subjected to the assuming, the modal analysis and the ambient vibration calculations are carried out. The computing results of inherent frequencies, measure points’ root mean square(RMS) displacements and the transfer characteristics of four kinematic interface positions are accordant with that of the test results. The compared results show that the method modeling the kinematic interface joints is feasible in the paper.

Prediction of Residual Stress Distributions in Welded Sections of P92 Pipes with Small Diameter and Thick Wall based on 3D Finite Element Simulation

2015 ◽  
Vol 34 (3) ◽  
Author(s):  
Xiaowei Wang ◽  
Jianming Gong ◽  
Yanping Zhao ◽  
Yanfei Wang
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Small Diameter ◽  
Fe Analysis ◽  
Thick Wall ◽  
Fe Model ◽  
Stress Distributions ◽  
Residual Stress Field ◽  
Heat Treated

AbstractThis study used ABAQUS finite element (FE) software to investigate the residual stress distributions of P92 welded pipes in both the as-weld and post weld heat treated (PWHT) condition. Sequential coupling quasi-static thermo-mechanical in conjunction with moving double ellipsoidal heat source and an element add/remove technique to simulate deposition of new weld material, are combined in the 3D FE analysis. To validate the simulation results, the residual stresses in axial direction at the surface of pipe were measured by X-ray diffraction technique and compared with the results of FE analysis. Detailed characteristic distributions of the residual stresses are discussed. Results show that the FE model can predict the residual stress distributions satisfactorily. Highest residual stresses on the outer surface are found in the last weld bead to be deposited. And the highest tensile residual stress for the full welded section take place in heat affected zone (HAZ) near the middle thickness. Larger residual sstress can be found around the welding start point along the pipe circumference. Comparison of heat treated specimen and untreated specimen illustrates that PWHT has a strong effect on the residual stress field.

scholarly journals Influence of Circumferential Flaw Length on Internal Burst Pressure of a Wall-Thinned Pipe

2012 ◽  
Author(s):  
Masataka Tsuji ◽  
Toshiyuki Meshii
Keyword(s):  
Finite Element Analysis ◽  
Fracture Mode ◽  
Experimental Results ◽  
The Other ◽  
Burst Pressure ◽  
Test Results ◽  
Element Analysis ◽  
Burst Test ◽  
Axial Crack ◽  
Planar Flaw

The effect of the circumferential angle of a flaw θ on the internal burst pressure pf of pipes with artificial wall-thinned flaws is examined. When evaluating pf of wall-thinned straight pipes, the effect of θ has been conventionally not regarded as important. Therefore, a burst pressure equation for an axial crack inside a cylinder (Fig. 1, left), such as Kiefner’s equation [1] is widely used [2], [3]. However, it should be noted that there exist the following implicit assumptions when applying the equation for planar flaws to non-planar flaws. 1) The fracture mode of a non-planar flaw under consideration is identical with that of the crack. 2) The effect of θ, which is not considered for an axial crack on pf, is small or negligible. However, from the systematic burst test results of carbon pipes with artificial wall-thinned flaws, Meshii [4] showed that these implicit assumptions may not be correct. On the other hand, the significance of the effect of the fracture mode on pf and the condition for θ to affect pf are not clear. Therefore, in this paper, Meshii’s experimental results are evaluated in farther detail. The purpose of the evaluation was set to clarify the effect of θ on pf. Specifically, the significance of flaw configuration (axial length δz and wall-thinning ratio t1/t) was studied in relation to θ and pf. In addition, a simulation of the effect by a Finite Element Analysis (FEA) was attempted. From the experimental results, θ tended to affect pf in cases with large δz, and t1/t also was correlated to a decrease in pf with the increase of θ. These tendencies were successfully simulated by the elastic-plastic FEA. This effect means the burst pressure predicted for a crack with identical ligament thickness decreases with the increase of θ, so that the effect by θ on pf should not be ignored.

Prediction of Tread Pattern Wear by an Explicit Finite Element Model3

2007 ◽  
Vol 35 (4) ◽  
pp. 276-299 ◽  
Author(s):  
J. C. Cho ◽  
B. C. Jung
Keyword(s):  
Finite Element ◽  
Wear Rate ◽  
Tangential Stress ◽  
Rate Equation ◽  
Constitutive Equations ◽  
Slip Velocity ◽  
Test Results ◽  
Explicit Finite Element ◽  
Driving Condition ◽  
Driving Conditions

Abstract Tread pattern wear is predicted by using an explicit finite element model (FEM) and compared with the indoor drum test results under a set of actual driving conditions. One pattern is used to determine the wear rate equation, which is composed of slip velocity and tangential stress under a single driving condition. Two other patterns with the same size (225/45ZR17) and profile are used to be simulated and compared with the indoor wear test results under the actual driving conditions. As a study on the rubber wear rate equation, trial wear rates are assumed by several constitutive equations and each trial wear rate is integrated along time to yield the total accumulated wear under a selected single cornering condition. The trial constitutive equations are defined by independently varying each exponent of slip velocity and tangential stress. The integrated results are compared with the indoor test results, and the best matching constitutive equation for wear is selected for the following wear simulation of two other patterns under actual driving conditions. Tens of thousands of driving conditions of a tire are categorized into a small number of simplified conditions by a suggested simplification procedure which considers the driving condition frequency and weighting function. Both of these simplified conditions and the original actual conditions are tested on the indoor drum test machines. The two results can be regarded to be in good agreement if the deviation that exists in the data is mainly due to the difference in the test velocity. Therefore, the simplification procedure is justified. By applying the selected wear rate equation and the simplified driving conditions to the explicit FEM simulation, the simulated wear results for the two patterns show good match with the actual indoor wear results.

scholarly journals Theoretical analysis and experimental research on multi-layer elastic damping track structure

2021 ◽  
Vol 13 (2) ◽  
pp. 168781402199497
Author(s):  
Guanghui Xu ◽  
Shengkai Su ◽  
Anbin Wang ◽  
Ruolin Hu
Keyword(s):  
Finite Element ◽  
Analytical Solution ◽  
Finite Element Simulation ◽  
Reaction Force ◽  
Vibration Reduction ◽  
Vertical Direction ◽  
Propagation Path ◽  
Track Structure ◽  
Test Results ◽  
Element Simulation

The increase of axle load and train speed would cause intense wheelrail interactions, and lead to potential vibration related problems in train operation. For the low-frequency vibration reduction of a track system, a multi-layer track structure was proposed and analyzed theoretically and experimentally. Firstly, the analytical solution was derived theoretically, and followed by a parametric analysis to verify the vibration reduction performance. Then, a finite element simulation is carried out to highlight the influence of the tuned slab damper. Finally, the vibration and noise tests are performed to verify the results of the analytical solution and finite element simulation. As the finite element simulation indicates, after installation of the tuned slab damper, the peak reaction force of the foundation can be reduced by 60%, and the peak value of the vertical vibration acceleration would decrease by 50%. The vibration test results show that the insertion losses for the total vibration levels are 13.3 dB in the vertical direction and 21.7 dB in the transverse direction. The noise test results show that the data of each measurement point is smoother and smaller, and the noise in the generating position and propagation path can be reduced by 1.9 dB–5.5 dB.

scholarly journals A Practical Finite Element Modeling Strategy to Capture Cracking and Crushing Behavior of Reinforced Concrete Structures

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 506 ◽  
Author(s):  
Alexandre Mathern ◽  
Jincheng Yang
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Constitutive Relations ◽  
Fe Analysis ◽  
Rc Beams ◽  
Cracking Behavior ◽  
Concrete Cracking ◽  
Rc Structures ◽  
Nonlinear Fe Analysis ◽  
Modeling Strategy

Nonlinear finite element (FE) analysis of reinforced concrete (RC) structures is characterized by numerous modeling options and input parameters. To accurately model the nonlinear RC behavior involving concrete cracking in tension and crushing in compression, practitioners make different choices regarding the critical modeling issues, e.g., defining the concrete constitutive relations, assigning the bond between the concrete and the steel reinforcement, and solving problems related to convergence difficulties and mesh sensitivities. Thus, it is imperative to review the common modeling choices critically and develop a robust modeling strategy with consistency, reliability, and comparability. This paper proposes a modeling strategy and practical recommendations for the nonlinear FE analysis of RC structures based on parametric studies of critical modeling choices. The proposed modeling strategy aims at providing reliable predictions of flexural responses of RC members with a focus on concrete cracking behavior and crushing failure, which serve as the foundation for more complex modeling cases, e.g., RC beams bonded with fiber reinforced polymer (FRP) laminates. Additionally, herein, the implementation procedure for the proposed modeling strategy is comprehensively described with a focus on the critical modeling issues for RC structures. The proposed strategy is demonstrated through FE analyses of RC beams tested in four-point bending—one RC beam as reference and one beam externally bonded with a carbon-FRP (CFRP) laminate in its soffit. The simulated results agree well with experimental measurements regarding load-deformation relationship, cracking, flexural failure due to concrete crushing, and CFRP debonding initiated by intermediate cracks. The modeling strategy and recommendations presented herein are applicable to the nonlinear FE analysis of RC structures in general.

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