Fatigue Assessment of Pipeline With Plain Dents Under Cyclic Pressure Loading Using Finite Element Method

2016 ◽  
Author(s):  
Michael Durowoju ◽  
Yongchang Pu ◽  
Simon Benson ◽  
Julia Race
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
Material Strength ◽  
Pipe Material ◽  
Element Analysis ◽  
Fatigue Assessment ◽  
Pipe Geometry ◽  
Dent Depth

One of the major challenges faced in fatigue assessment today is determining the stress concentration factor ‘SCF’ associated with the dents, which are used with appropriate SN curves to determine the fatigue life. This historically has been determined empirically or by using finite element analysis. This paper presents finite element analysis on a parametric range of industry pipes (both offshore and onshore) to extract SCF data used for fatigue assessment. The parametric dataset focuses on the effects of pipe geometry, dent geometry, material properties and pressure cycling on the prediction of the fatigue life. This parametric dataset will eventually be used to develop an algorithm for fatigue prediction using an artificial neural network. Two types of indenters (Dome and Bar) are used to simulate circumferential and longitudinal dents. Four different dent depths ranging from 2% d/D to 10% d/D are also simulated to investigate the effect of dent geometry. Four different pipe grades (X42, X65, X80 and X100) are analyzed to investigate the effect of pipe materials on dent fatigue. Similarly, eight pipes with different diameter to thickness ratio D/t ranging from 18–96 are analyzed to investigate the effect of pipe geometry. Stresses are computed at both 50% SMYS and 72% SMYS to investigate the effect of pressure variation. The results from this study indicate that longitudinal dents have higher stress concentrations compared to circumferential dents of similar dent depth. Results also indicate that the re-round dent depth (i.e. dent depth after pressurization) increases with increasing D/t and increasing dent depth. Similarly, the pipe material has a major effect on the fatigue life. Pipes with higher material strength have higher stress concentration compared to pipes with lower strength of similar dent depth. The stress concentration factors SCF associated with the dents are then computed.

Cross-Weld Tensile Properties of Girth Welds for Strain-Based Designed Pipelines

2006 ◽  
Author(s):  
J. T. Bowker ◽  
J. A. Gianetto ◽  
G. Shen ◽  
W. Tyson ◽  
D. Horsley
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Weld Metal ◽  
Tensile Properties ◽  
True Strain ◽  
Standard Test ◽  
Pipe Material ◽  
Lower Stress ◽  
Element Analysis

For strain-based designed pipelines it is important to understand the relative tensile properties of both weld metal and pipe material in the pipe axial direction. The evaluation of weld metal tensile properties has typically involved extracting all-weld-metal tensile samples in the direction of the weld. In this study an evaluation of the application of “waisted” tensile samples to generate data has been conducted. Initial studies focused on finite element analysis to generate geometry factors for a range of specimen configurations to correct for the level of stress triaxiality. These factors were then applied to samples extracted from X70 and X100 pipe material to establish the validity of this approach. It was shown that, regardless of the radius of waisted specimens, very good agreement was obtained between the geometry-factor-corrected stress-strain curves and those generated from standard test specimens at true strains above 0.02. To achieve a better agreement between the corrected and standard tensile curves in and around yield it was necessary to use samples with a large radius (9 mm) where the stress concentration was low. Finite element analysis provided supporting evidence with respect to the effect of stress concentration associated with different specimen radii on the yielding pattern. These waisted samples were used to measure the tensile properties in all-weld-metal and cross-weld-metal directions for an X70 double joint (DJ) weld and an X100 mechanized pulsed gas metal arc (P-GMA) weld. Waisted samples taken from the double joint weld on X70 with radii of 3 mm and 9 mm showed no difference with respect to their orientation. Once stress-strain behaviour was corrected for geometry, the curves were in excellent agreement with the standard test specimens above 0.01 true strain in the case of the sample of radius 3 mm and for the whole curve for the sample with radius 9 mm. An assessment of the X100 weld identified a small difference between all-weld-metal and cross-weld-metal directions, with the latter displaying a lower stress between yielding and 0.03 true strain. The use of waisted samples of larger radius generated much better agreement with the standard specimens associated with their lower stress concentration. Because of the finite weld width, consideration needs to be given to the extent to which the reduced section may extend beyond the weld and the potential effect of mismatch in strength.

Finite Element Analysis of Dual-Frequency Vibrating Screen

2012 ◽  
Vol 479-481 ◽  
pp. 2124-2128 ◽  
Author(s):  
Yong Jun Hou ◽  
Pan Fang ◽  
Lian Zeng
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Concentration ◽  
High Frequency ◽  
Element Model ◽  
Dual Frequency ◽  
Element Analysis ◽  
Vibrating Screen ◽  
Sufficient Strength

In order to study the stress distribution of dual-frequency vibrating screen and ensure the screen box has sufficient strength and longevity, a finite element model of dual-frequency vibrating screen was built, and the stress, modes and fatigue life of the screen box were analyzed. The results indicate that, the stress concentration appears at the contacting parts between the crossbeam and the stiffener of motor seat, the crossbeam, L-type stiffening plate, baffle of material added and screen box. The middle of crossbeam and the L-type stiffening plate are weaker parts of fatigue, they are easily fatigue failure under high frequency vibration.

Stress Analysis and Structure Optimization for the Opening Flat Cover of Pressure Vessels

2012 ◽  
Vol 538-541 ◽  
pp. 3253-3258 ◽  
Author(s):  
Jun Jian Xiao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Stress Analysis ◽  
Structure Optimization ◽  
Pressure Vessels ◽  
Secondary Stress ◽  
Element Analysis ◽  
Primary Stress ◽  
Flat Cover

According to the results of finite element analysis (FEA), when the diameter of opening of the flat cover is no more than 0.5D (d≤0.5D), there is obvious stress concentration at the edge of opening, but only existed within the region of 2d. Increasing the thickness of flat covers could not relieve the stress concentration at the edge of opening. It is recommended that reinforcing element being installed within the region of 2d should be used. When the diameter of openings is larger than 0.5D (d>0.5D), conical or round angle transitions could be employed at connecting location, with which the edge stress decreased remarkably. However, the primary stress plus the secondary stress would be valued by 3[σ].

scholarly journals Prediction of Thermal Fatigue Life of Lead-Free BGA Solder Joints by Finite Element Analysis

2001 ◽  
Vol 42 (5) ◽  
pp. 809-813 ◽  
Author(s):  
Young-Eui Shin ◽  
Kyung-Woo Lee ◽  
Kyong-Ho Chang ◽  
Seung-Boo Jung ◽  
Jae Pil Jung
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Lead Free ◽  
Element Analysis ◽  
Thermal Fatigue Life

An Estimation Formula of the Stress Concentration Factor of the Butt-Welded Joint

2007 ◽  
Vol 353-358 ◽  
pp. 1995-1998
Author(s):  
Byeong Choon Goo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Stress Concentration ◽  
Gas Metal Arc Welding ◽  
Element Analysis ◽  
Butt Weld ◽  
Estimation Formula ◽  
Metal Arc Welding ◽  
Concentration Factors ◽  
Stress Concentration Factors

The purpose of this paper is to develop an estimation formula of stress concentration factors of butt-welded components under tensile loading. To investigate the influence of weld bead profiles on stress concentration factors of double V groove butt-welded joints, butt-welded specimens were made by CO2 gas metal arc welding. And the three main parameters, the toe radius, flank angle and bead height were measured by a profile measuring equipment. By using the measured data, the influence of three parameters on the stress concentration factors was investigated by a finite element analysis. It is shown that the three parameters have similar effects on the stress concentration factors. According to the simulation results, a formula to estimate the stress concentration factors of butt-weld welded structures was proposed and the estimated concentration factors from the formula were compared with the results obtained by the finite element analysis. The two results are in a good agreement.

Stress and Fatigue Life Modeling of Cannon Breech Closures Including Effects of Material Strength and Residual Stress

2000 ◽  
Vol 123 (1) ◽  
pp. 150-154
Author(s):  
John H. Underwood ◽  
Michael J. Glennon
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Fatigue Life ◽  
Yield Strength ◽  
Residual Stresses ◽  
Solid Mechanics ◽  
Element Model ◽  
Pressure Vessels ◽  
Material Strength ◽  
Element Analysis

Laboratory fatigue life results are summarized from several test series of high-strength steel cannon breech closure assemblies pressurized by rapid application of hydraulic oil. The tests were performed to determine safe fatigue lives of high-pressure components at the breech end of the cannon and breech assembly. Careful reanalysis of the fatigue life tests provides data for stress and fatigue life models for breech components, over the following ranges of key parameters: 380–745 MPa cyclic internal pressure; 100–160 mm bore diameter cannon pressure vessels; 1040–1170 MPa yield strength A723 steel; no residual stress, shot peen residual stress, overload residual stress. Modeling of applied and residual stresses at the location of the fatigue failure site is performed by elastic-plastic finite element analysis using ABAQUS and by solid mechanics analysis. Shot peen and overload residual stresses are modeled by superposing typical or calculated residual stress distributions on the applied stresses. Overload residual stresses are obtained directly from the finite element model of the breech, with the breech overload applied to the model in the same way as with actual components. Modeling of the fatigue life of the components is based on the fatigue intensity factor concept of Underwood and Parker, a fracture mechanics description of life that accounts for residual stresses, material yield strength and initial defect size. The fatigue life model describes six test conditions in a stress versus life plot with an R2 correlation of 0.94, and shows significantly lower correlation when known variations in yield strength, stress concentration factor, or residual stress are not included in the model input, thus demonstrating the model sensitivity to these variables.

scholarly journals Fatigue life prediction of upper arm suspension using strain life approach

2019 ◽  
Vol 17 (1) ◽  
pp. 25-40 ◽  
Author(s):  
Hafida Kahoul ◽  
Samira Belhour ◽  
Ahmed Bellaouar ◽  
Jean Paul Dron
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Aluminium Alloys ◽  
Fatigue Analysis ◽  
Vertical Force ◽  
Upper Arm ◽  
Element Analysis ◽  
Content Type ◽  
Critical Location

Purpose This paper aims to present the fatigue life behaviour of upper arm suspension. The main objectives are to predict the fatigue life of the component and to identify the critical location. In this analysis, three aluminium alloys were used for the suspension, and their fatigue life was compared to select the suitable material for the suspension arm. Design/methodology/approach CAD model was prepared using Solid Works software, and finite element analysis was done using ANSYS 14.0 software by importing the Parasolid file to ANSYS. The model is subjected to loading and boundary conditions; the authors consider a vertical force with constant amplitude applied at the bushing that connected to the tire, the others two bushing that connected to the body of the car are constraint. Tetrahedral elements given enhanced results as compared to other types of elements; therefore, the elements (TET 10) are used. The maximum principal stress was considered in the linear static analysis, and fatigue analysis was done using strain life approach. Findings Life and damage are evaluated and the critical location was considered at node 63,754. From the fatigue analysis, aluminium alloys 7175-T73 (Al 90%-Zn 5.6%-Mg 2.5% -… …) and 2014-T6 (Al 93.5%-Cu 4.4%-Mg 0.5%… …) present a similar behaviour as compared to 6061-T6 (Al 97.9%-Mg 1.0%-Si 0.6%… … .); in this case of study, these lather are considered to be the materials of choice to manufacture the suspension arms; but 7175-T73 aluminium alloys remain the material with a better resistance to fatigue. Originality/value By the finite element analysis method and assistance of ANSYS software, it is able to analyse the different car components from varied aspects such as fatigue, and consequently save time and cost. For further research, the experimental works under controlled laboratory conditions should be done to determine the validation of the result from the software analysis.

Finite Element Analysis of the Rolling Contact Fatigue Life of Railcar Wheels

2008 ◽  
Vol 575-578 ◽  
pp. 1461-1466
Author(s):  
Byeong Choon Goo ◽  
Jung Won Seo
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Element Analysis ◽  
Railway Vehicles ◽  
Contact Fatigue Life

Railcar wheels and axles belong to the most critical components in railway vehicles. The service conditions of railway vehicles have been more severe in recent years due to speed-up. Therefore, a more precise evaluation of railcar wheel life and safety has been requested. Wheel/rail contact fatigue and thermal cracks due to braking are two major mechanisms of the railcar wheel failure. One of the main sources influencing on the contact zone failure is residual stress. The residual stress in wheels formed during heat treatment in manufacturing changes in the process of braking. Thus the fatigue life of railcar wheels should be estimated by considering both thermal stress and rolling contact. Also, the effect of residual stress variation due to manufacturing process and braking process should be included in simulating contact fatigue behavior. In this paper, an evaluation procedure for the contact fatigue life of railcar wheels considering the effects of residual stresses due to heat treatment, braking and repeated contact load is proposed. And the cyclic stressstrain history for fatigue analysis is simulated by finite element analysis for the moving contact load.

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