Structural Integrity of Steel Hydrocarbon Pipelines With Local Wall Distortions

2014 ◽  
Author(s):  
Aglaia E. Pournara ◽  
Spyros A. Karamanos ◽  
Theocharis Papatheocharis ◽  
Philip C. Perdikaris
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Local Stress ◽  
Element Analysis ◽  
Experimental Procedure ◽  
Steel Pipes ◽  
The Finite Element Analysis ◽  
Loading Case ◽  
Pipeline Wall ◽  
Local Distortions

Local distortions on pipeline wall in the form of dents or buckles may constitute a threat for the structural integrity of the steel pipeline. In the present paper, experimental research supported by numerical simulation is reported to investigate the structural integrity of smoothly dented steel pipes. A series of six (6) full-scale experiments on 6-inch X52 pipes has been carried out, and numerical simulations have also been conducted. The dented steel pipes are subjected to cyclic loading (bending or pressure) in order to estimate their residual strength and remaining fatigue life. The finite element analysis simulate the experimental procedure for each type of deformation and loading case, in order to estimate the local stress and strain distributions at the dented region. Based on the numerical results, fatigue life is predicted and compared with the experimental results. The results of the present study are aimed at evaluating existing guidelines and methodologies towards appropriate assessment of local wall distortions in steel pipelines.

Structural Integrity of Buckled Steel Pipes

2015 ◽  
Author(s):  
Aglaia E. Pournara ◽  
Theocharis Papatheocharis ◽  
Spyros A. Karamanos ◽  
Philip C. Perdikaris
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Structural Integrity ◽  
Local Strain ◽  
Element Analysis ◽  
Steel Pipeline ◽  
Steel Pipes ◽  
The Finite Element Analysis ◽  
Loading Case ◽  
Pipeline Wall

Local distortions on steel pipeline wall in the form of buckles may constitute a threat for the structural integrity of the steel pipeline. In the present paper, experimental research supported by numerical simulation is reported to investigate the structural integrity of buckled steel pipes. A series of six (6) full-scale experiments has been carried out on 6-inch X52 pipes, followed by finite element simulations. The buckled steel pipes are subjected to cyclic loading (bending or pressure) in order to estimate their residual strength and remaining fatigue life. The finite element analysis simulates the experimental procedure for each type of deformation and loading case, in order to estimate the local strain distributions at the buckled region. Based on the numerical results, fatigue life is predicted and compared with the experimental results using an appropriate defined damage factor. The results of the present study are aimed at evaluating existing guidelines and methodologies towards appropriate assessment of local wall distortions in steel pipelines.

Mechanical Behavior of Dented Steel Pipes Subjected to Bending and Pressure Loading

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Aglaia E. Pournara ◽  
Theocharis Papatheocharis ◽  
Spyros A. Karamanos ◽  
Philip C. Perdikaris
Keyword(s):  
Fatigue Life ◽  
Structural Integrity ◽  
Numerical Study ◽  
Experimental Testing ◽  
Local Stress ◽  
Life Assessment ◽  
Structural Safety ◽  
Pressure Loading ◽  
Steel Pipes ◽  
Remaining Fatigue Life

The presence of dents on steel pipeline wall may constitute a threat for pipeline structural safety. Experimental testing results supported by numerical simulations are reported, in an attempt to assess the structural integrity of smoothly dented (nongauged) steel pipes. Ten experiments on 6 in diameter X52 steel pipes are reported, where dented steel pipes are subjected to bending and pressure loading, in order to estimate their residual strength and remaining fatigue life. Six specimens were subjected to cyclic bending loading, whereas four dented pipe specimens, following cyclic pressure loading, have been pressurized to burst to determine their ultimate pressure capacity. Numerical simulation of the testing procedure and, in particular, the loading pattern of each specimen (denting and cyclic loading) has also been performed so that local stress and strain distributions at the dented region are calculated accurately. Based on the finite element results, a simple and efficient fatigue assessment methodology is adopted, to estimate the remaining fatigue life and the predictions were found to compare with the experimental results. Finally, following a parametric numerical study, strain concentration factors (SNCFs) for dented pipes subjected to bending are calculated, to be used in fatigue life assessment.

Response of Mild Steel Pipes Under High Mass Low Velocity Impacts

2014 ◽  
Author(s):  
Shamsoon Fareed ◽  
Ian May
Keyword(s):  
Finite Element ◽  
Mild Steel ◽  
Impact Energy ◽  
High Mass ◽  
Low Velocity ◽  
Element Analysis ◽  
Steel Pipes ◽  
Impact Tests ◽  
The Finite Element Analysis ◽  
The Impact

Accidental loads, for example, due to heavy dropped objects, impact from the trawl gear and anchors of fishing vessels can cause damage to pipelines on the sea bed. The amount of damage will depend on the impact energy. The indentation will be localized at the contact area of the pipe and the impacting object, however, an understanding of the extent of the damage due to an impact is required so that if one should occur in practice an assessment can be made to determine if remedial action needs to be taken to ensure that the pipeline is still serviceable. There are a number of parameters, including the pipe cross section and impact energy, which influence the impact behaviour of a pipe. This paper describes the response, and assesses the damage, of mild steel pipes under high mass low velocity impacts. For this purpose full scale impacts tests were carried out on mild steel pipe having diameter of 457 mm, thickness of 25.4 mm and length of 2000 mm. The pipe was restrained along the base and a 2 tonnes mass with sharp impactor having a vertical downward velocity of 3870 mm/sec was used to impact the pipe transversely with an impact energy of 16 kJ. It was found from the impact tests that a smooth indentation was produced in the pipe. The impact tests were then used for validation of the non-linear dynamic implicit analyses using the finite element analysis software ABAQUS. Deformations at the impact zone, the rebound velocity, etc, recorded in the tests and the results of the finite element analysis were found to be in good agreement. The impact tests and finite element analyses described in this paper will help to improve the understanding of the response of steel pipes under impact loading and can be used as a benchmark for further finite element modelling of impacts on pipes.

Prediction of thermo-mechanical fatigue life of IN738 LC using the finite element analysis

2014 ◽  
Vol 15 (8) ◽  
pp. 1733-1737 ◽  
Author(s):  
Jeong-Min Lee ◽  
Chang-Sung Seok ◽  
Dongkeun Lee ◽  
Yongseok Kim ◽  
Junghan Yun ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Element Analysis ◽  
Mechanical Fatigue ◽  
The Finite Element Analysis

Fatigue Strength Study on Radial Bogie Vice Frame Based on Finite Element Analysis

2015 ◽  
Vol 723 ◽  
pp. 96-99
Author(s):  
Xiao Wei Wang ◽  
Mao Xiang Lang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Strength ◽  
Structural Strength ◽  
Simulation Software ◽  
Experimental Result ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
The Stability

The vice frame bears and transfers the forces and loads between the bogie and the vehicle body.The strength of the vice frame relates directly to the stability and smoothness of the vehicle. In this study, finite element analysis is utilized first to analyse the structural strength and fatigue life of the vice frame, and the recognize the weak parts of its structure in order to enhance its structural strength in the following design work.The finite element analysis is performed on a simulation software Ansys. Then an experiment is designed to test the fatigue strength of the vice frame. The experimental result indicates that the fatigue strength of the object corresponds to the standards and the finite element analysis has high feasibility in solving this kind of problem.

Life Assessment of Turbine Components Through Experimental and Numerical Investigations

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Dianyin Hu ◽  
Rongqiao Wang ◽  
Guicang Hou
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Life Prediction ◽  
Life Assessment ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Creep Fatigue ◽  
Turbine Component ◽  
Good Agreement

A new lifetime criterion for withdrawal of turbine components from service is developed in this paper based on finite element (FE) analysis and experimental results. Finite element analysis is used to determine stresses in the turbine component during the imposed cyclic loads and analytically predict a fatigue life. Based on the finite element analysis, the critical section is then subjected to a creep-fatigue test, using three groups of full scale turbine components, attached to an actual turbine disc conducted at 750 °C. The experimental data and life prediction results were in good agreement. The creep-fatigue life of this type of turbine component at a 99.87% survival rate is 30 h.

Analyses of Contact Pressure and Stress Amplitude Effects on Fretting Fatigue Life

2000 ◽  
Vol 123 (1) ◽  
pp. 85-93 ◽  
Author(s):  
K. Iyer ◽  
S. Mall
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Contact Pressure ◽  
Stress Amplitude ◽  
Normal Load ◽  
Contact Region ◽  
Local Stress ◽  
Fretting Fatigue ◽  
Element Analysis ◽  
Stress Ratios

Elastic-plastic finite element analyses of a cylinder-on-plate configuration, studied experimentally, were performed to provide an explanation for the decrease in fretting fatigue life with increasing contact pressure. Three values of normal load, namely 1338 N, 2230 N, and 3567 N, and three stress ratios (0.1, 0.5, and 0.7) were considered. Based on a previously determined dependency between contact pressure and friction coefficient, the effect of coefficient of friction was also evaluated. The deformation remained elastic under all conditions examined. Cyclic, interfacial stresses, and slips were analyzed in detail. The amplification of remotely applied cyclic stress in the contact region is shown to provide a rationale for the effect of contact pressure and stress amplitude on life. Comparisons with previous experiments indicate that the local stress range computed from finite element analysis may be sufficient for predicting fretting fatigue life. Further, the results suggest that the slip amplitude and shear traction may be neglected for this purpose.

Fatigue Life Evaluation of Vehicle Wheel Bolts under Random Loading

2005 ◽  
Vol 297-300 ◽  
pp. 1770-1775 ◽  
Author(s):  
Young Woo Choi ◽  
Byeong Wook Noh ◽  
Kyung Chun Ham ◽  
Sung In Bae
Keyword(s):  
Fatigue Life ◽  
Residual Life ◽  
Three Dimensional ◽  
Real Life ◽  
Local Stress ◽  
Tensile Tests ◽  
Fatigue Tests ◽  
Random Loading ◽  
Element Analysis ◽  
Three Dimensional Finite Element

The fatigue life of hexagon head and socket head bolts, attached to vehicle a wheel, is assessed and the estimation of the residual life of existing bolts in vehicle wheel is investigated. Field- measured load histories were applied in this test. Tensile tests and fatigue tests were performed to evaluate the effect of tightening torque and to obtain the basic experimental data. A three-dimensional finite element analysis was also performed to evaluate the local stress fields. Miner’s rule was used to predict the fatigue life of bolts. The results indicate the prediction of fatigue life of the bolts was in good agreement with the real life of vehicle wheel bolts in this test.

scholarly journals Influence of Weld Toe Radii on Fatigue Life Prediction

2018 ◽  
Vol 165 ◽  
pp. 22025 ◽  
Author(s):  
Kin Shun Tsang ◽  
John H. L. Pang ◽  
Hsin Jen Hoh
Keyword(s):  
Fatigue Life ◽  
Stress Intensity ◽  
Life Prediction ◽  
Crack Depth ◽  
Local Stress ◽  
Fatigue Life Prediction ◽  
Element Analysis ◽  
Weld Toe ◽  
Point Bend ◽  
Welded Pipe

A study was carried out to investigate the influence of the weld toe radii on the fatigue strength of butt welded joints loaded in bending and tension. Fatigue analysis starting from weld toe cracks in marine and offshore welded pipe specimens were conducted using cut-out four-point bend fatigue test specimens. Fatigue life can be enhanced by reducing the local stress concentration generated by weld toe radius effects. This study investigated the effect of different weld toe radii on the stress intensity factor at the region of the weld toe through Finite Element Analysis (FEA). FEA was used to model a butt welded steel plate extracted from a pipe subject to tension and four-point bend loading. Semi-elliptical surface (SESC) cracks were modeled at the weld toe region with different SESC crack depth and surface crack length. Four weld toe radii and two modes of loading were investigated. The stress intensity factors, weald toe magnification factors, or Mkc and Mka are reported and used for fatigue life prediction.

The Finite Element Analysis of Car's Rear Axle and Prediction of Fatigue Life

2014 ◽  
Vol 490-491 ◽  
pp. 616-620 ◽  
Author(s):  
Li Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Rear Axle ◽  
Stress And Strain ◽  
Element Analysis ◽  
The Finite Element Analysis ◽  
Structure Strength ◽  
Strength And Stiffness ◽  
Calculation Analysis

This paper makes a static strength calculation and fatigue life prediction of a car's rear axle. To find out the dangerous stress and strain points of the bridge shell by making calculation analysis of the structure strength and stiffness of the rear axle bridge shell by using finite element analysis software, MSC.Patran and MSC.Nastran. Using MSC.Fatigue software on the rear axle to make an analysis of its fatigue life base on the finite element analysis, and make a modal analysis with MSC.Nastran software.

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