A Comparative Fatigue Analysis Study Based on RCC-M Code and EN13-445 Standard Through Actual Test Cases

2017 ◽  
Author(s):  
François Billon ◽  
Julien Halleguen
Keyword(s):  
Fatigue Curve ◽  
Fatigue Analysis ◽  
Combination Method ◽  
Test Cases ◽  
Fe Model ◽  
Support Ring ◽  
Butt Weld ◽  
Full Penetration ◽  
Shell Type ◽  
Welding Procedure

This document is aimed at comparing the fatigue analysis methods based on the RCC-M code and on the harmonized standard EN 13445-3 with a view to quantifying the associated deviations and uncertainties, at each step of the calculation, by taking into account every aspect of each code such as calculation thickness of the FE model, physical properties, combination method and fatigue curve. This comparison study consists in analyzing the 4 Test Cases (TC) described below: • TC1: Study of the cylindrical-edge transition cone with its upper shell/shell type full-penetration butt weld. • TC2: Study of the feedwater nozzle (FWN) with its full-penetration weld on the nozzle support ring. • TC3: Study of the misalignment effect of neutral axes at shell/shell type full-penetration butt weld level. • TC4: Study of the out-of-roundness effect at shell/shell type full-penetration butt weld level. The welds considered in this study are full-penetration butt welds whose RCC-M quality is Level 1, whose welding procedure has been qualified, which are dressed, made flush with base metal by grinding and which have been fully (100%) inspected by NDE.

Managing Flow Induced Vibration in Subsea Jumpers

2021 ◽  
Author(s):  
Rakshith Naik ◽  
Yetzirah Urthaler ◽  
Scot McNeill ◽  
Rafik Boubenider
Keyword(s):  
Dynamic Properties ◽  
Fatigue Analysis ◽  
Management Program ◽  
Measured Data ◽  
Operating Conditions ◽  
Valuable Insight ◽  
Fe Model ◽  
Flow Induced Vibration ◽  
Vibration Measurements

Abstract Certain subsea jumper design features coupled with operating conditions can lead to Flow Induced Vibration (FIV) of subsea jumpers. Excessive FIV can result in accumulation of allowable fatigue damage prior to the end of jumper service life. For this reason, an extensive FIV management program was instated for a large development in the Gulf of Mexico (GOM) where FIV had been observed. The program consisted of in-situ measurement, modeling and analysis. Selected well and flowline jumpers were outfitted with subsea instrumentation for dedicated vibration testing. Finite Element (FE) models were developed for each jumper and refined to match the dynamic properties extracted from the measured data. Fatigue analysis was then carried out using the refined FE model and measured response data. If warranted by the analysis results, action was taken to mitigate the deleterious effects of FIV. Details on modeling and data analysis were published in [5]. Herein, we focus on the overall findings and lessons learned over the duration of the program. The following topics from the program are discussed in detail: 1. In-situ vibration measurement 2. Overall vibration trends with flow rate and lack of correlation of FIV to flow intensity (rho-v-squared); 3. Vibration and fatigue performance of flowline jumpers vs. well jumpers 4. Fatigue analysis conservatism Reliance on screening calculations or predictive FE analysis could lead to overly conservative operational limits or a high degree of fatigue life uncertainty in conditions vulnerable to FIV. It is proposed that in-situ vibration measurements followed by analysis of the measured data in alignment with operating conditions is the best practice to obtain a realistic understanding of subsea jumper integrity to ensure safe and reliable operation of the subsea system. The findings from the FIV management program provide valuable insight for the subsea industry, particularly in the areas of integrity management of in-service subsea jumpers; in-situ instrumentation and vibration measurements and limitations associated with predictive analysis of jumper FIV. If learnings, such as those discussed here, are fed back into design, analysis and monitoring guidelines for subsea equipment, the understanding and management of FIV could be dramatically enhanced compared to the current industry practice.

scholarly journals Fatigue life prediction in a door hinge system under uni-axial and multi-axial loading conditions

2021 ◽  
Author(s):  
Sacheen Bekah
Keyword(s):  
Axial Loading ◽  
Fatigue Analysis ◽  
Design Stage ◽  
Fe Model ◽  
Preliminary Design ◽  
Standard Requirement ◽  
Ground Vehicle ◽  
Design Engineers ◽  
Door Hinge ◽  
Preliminary Design Stage

This thesis presents the use of Finite Element (FE) based fatigue analysis to locate the critical point of crack initiation and predict life in a door hinge system that is subjected to both uni-axial and multi-axial loading. The results are experimentally validated. The FE model is further used to obtain an optimum design per the standard requirement in the ground vehicle industry. The accuracy of the results showed that FE based fatigue analysis can be successfully employed to reduce costly and time-consuming experiments in the preliminary design stage. Numerical analysis also provides the product design engineers with substantial savings, enabling the testing of fewer prototypes.

scholarly journals Fatigue life prediction in a door hinge system under uni-axial and multi-axial loading conditions

2021 ◽  
Author(s):  
Sacheen Bekah
Keyword(s):  
Axial Loading ◽  
Fatigue Analysis ◽  
Design Stage ◽  
Fe Model ◽  
Preliminary Design ◽  
Standard Requirement ◽  
Ground Vehicle ◽  
Design Engineers ◽  
Door Hinge ◽  
Preliminary Design Stage

This thesis presents the use of Finite Element (FE) based fatigue analysis to locate the critical point of crack initiation and predict life in a door hinge system that is subjected to both uni-axial and multi-axial loading. The results are experimentally validated. The FE model is further used to obtain an optimum design per the standard requirement in the ground vehicle industry. The accuracy of the results showed that FE based fatigue analysis can be successfully employed to reduce costly and time-consuming experiments in the preliminary design stage. Numerical analysis also provides the product design engineers with substantial savings, enabling the testing of fewer prototypes.

Evaluation of Welding Residual Stress Based on Temper Bead Welding Technique

2011 ◽  
Vol 418-420 ◽  
pp. 1208-1212 ◽  
Author(s):  
Xian Shi ◽  
Yi Liang Zhang ◽  
Jian Ping Zhao ◽  
Rui Bin Gou
Keyword(s):  
Residual Stress ◽  
Engineering Application ◽  
Maximum Principal Stress ◽  
Welding Residual Stress ◽  
Ray Method ◽  
Butt Weld ◽  
Welding Procedure ◽  
16Mn Steel ◽  
Better Than ◽  
Welding Technique

To reduce welding residual stress (WRS) of a class 3 pressure vessel during the reconstruction, temper bead welding technique (TBWT) was applied to the container. To compare WRS causing by common welding and TBWT, WRS of the two different kinds of welded specimens of 16Mn steel were measured and evaluated by X-ray method. To study the effect of butt weld reinforcement height on WRS, welds with and without weld reinforcement were measured. The results show that longitudinal stress was reduced obviously and the lateral stress is the maximum principal stress for TBWT; WRS of TBWT T-shape specimens were obviously decreased which proves TBWT is better than common welding procedure; WRS was decreased by more than 25% after removing the weld reinforcement and further proves that it is one of effective ways to reduce WRS in engineering application.

Fracture Mechanics Based Mooring Fatigue Analysis for a Semi-Submersible Subjected to Triple Narrow-Band Loading Processes

2019 ◽  
Author(s):  
Xutian Xue ◽  
Nian-Zhong Chen ◽  
Yongchang Pu
Keyword(s):  
Fatigue Life ◽  
Fracture Mechanics ◽  
Fatigue Analysis ◽  
Second Order ◽  
Combination Method ◽  
Mooring System ◽  
Initial Surface ◽  
Loop Current ◽  
Mooring Lines ◽  
First Order

Abstract In the general offshore operating locations, mooring systems are normally considered to be primarily affected by environmental loadings induced by waves, wind and current. WF motion induced by first-order waves, LF motion induced by second-order waves and wind would make the most contribution to the fatigue damage of mooring lines. However, it was reported recently that in the Gulf of Mexico (GoM), the fatigue life of mooring lines can be significantly affected by the vortex induced motion (VIM) induced by loop current. The aim of this presented paper is to address the influence of VIM on fatigue life of the mooring system operating at the central of the GoM through performing a fracture mechanics (FM) based fatigue analysis for an offshore mooring system. A frequency-domain mooring analysis for the semi-submersible is conducted where WF motion induced by first-order waves, LF motion induced by second-order waves and wind, and VIM induced by loop current are taken into account. WF motion, LF motion and VIM are treated as three independent loading processes. A wide-band loading combination method is then used for predicting the loading processes acting on the mooring system combining WF motion, LF motion and VIM. A fracture mechanics based analysis is performed to examine the fatigue life of mooring system, in which initial surface cracks in previous existence are assumed to grow from the surfaces of mooring chain links connecting to the fairleads. The stress intensity factor ranges to estimate the crack growth in the FM based analysis are obtained from a finite element (FE) analysis.

A Description of Local Material Properties Close to a Butt Weld

2013 ◽  
Vol 586 ◽  
pp. 146-149
Author(s):  
Pavel Hutař ◽  
Martin Ševčík ◽  
Ralf Lach ◽  
Zdeněk Knésl ◽  
Luboš Náhlík ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Material Properties ◽  
Radial Crack ◽  
Welded Joint ◽  
Butt Weld ◽  
Pipe System ◽  
Local Material ◽  
Mechanics Analysis ◽  
Welding Procedure ◽  
Local Material Properties

The paper presents a methodology for the lifetime assessment of welded polymer pipes. A fracture mechanics analysis of a butt-welded joint is performed by simulating radial crack growth in the nonhomogenous region of the pipe weld. It was found that the presence of material nonhomogeneity in the pipe weld caused by the welding procedure leads to an increase in the stress intensity factor of the radial crack and changes the usual failure mode of the pipe system. This can lead to a significant reduction in the lifetime of the pipe system.

Direct Calculation of Fatigue Damage of Ship Structure Details

2011 ◽  
Author(s):  
Zhiyuan Li ◽  
Jonas W. Ringsberg
Keyword(s):  
Fatigue Damage ◽  
Time Domain ◽  
Direct Calculation ◽  
Fatigue Analysis ◽  
Fe Model ◽  
Stress Concentration Factors ◽  
Rainflow Counting ◽  
Global And Local

Fatigue assessment of ships using the direct calculation approach has been investigated by numerous researchers. Normally, this approach is carried out as either a global model analysis, or as a local model structural analysis. The current investigation presents a case study of a container vessel where the global and local analyses procedures are combined. A nonlinear time-domain hydrodynamic analysis followed by a global FE analysis is employed to screen for the most severe locations of the global ship’s hull with regard to fatigue damage. Once these locations have been identified, a sub-modelling technique is employed to transfer global loads from the global FE model to local FE models that have high resolution of elements for local structure details. Results from a selection of local FE model simulations are presented. Stress concentration factors at four critical locations are calculated and compared with values recommended by classification guidelines. Results are presented from a short-term fatigue analysis which has been carried out using the rainflow counting method. Finally, a long-term fatigue analysis is performed in time-domain using a designed wave scatter diagram of representative sea states.

Modification and Extension of Screening Criteria for Fatigue Analysis

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Jun Shen ◽  
Mingwan Lu ◽  
Zhenyu Wang ◽  
Heng Peng ◽  
Yinghua Liu
Keyword(s):  
Fatigue Curve ◽  
Fatigue Analysis ◽  
Allowable Stress ◽  
Design Factor ◽  
Screening Criteria ◽  
Asme Code ◽  
Applicable Range ◽  
Number Of Cycles ◽  
Design Pressure

Abstract ASME Code VIII-2-2019 and previous versions provided three screening criteria for fatigue analysis. From edition 2004 to 2019, the design factor for material allowable stress decreased and the considered range of permissible cyclic number for design fatigue curve extended. However, screening criteria are almost unchanged except one restriction: If the specified number of cycles is greater than 106, then the screening criteria are not applicable and a fatigue analysis is required. In this paper, percentage limit of the design pressure in method A is modified and the specified number of cycles is extended. Some revision suggestions are also proposed to broaden the applicable range of the screening criterion.

scholarly journals Numerical and Experimental Study on Trimaran Cross-Deck Structure’s Fatigue Characteristics Based on the Spectral Fatigue Method

2019 ◽  
Vol 7 (3) ◽  
pp. 62
Author(s):  
Chunbo Zhen ◽  
Guoqing Feng ◽  
Tianlin Wang ◽  
Pengyao Yu
Keyword(s):  
Fatigue Test ◽  
Fatigue Analysis ◽  
Scale Model ◽  
Fe Model ◽  
Linear Potential ◽  
Structural Detail ◽  
Wave Load ◽  
Factors Influencing ◽  
Fatigue Characteristics ◽  
The Cross

Spectral fatigue analysis is performed on the trimaran cross-deck structural detail. A global finite element (FE) model with local fine meshes at hot spot locations is built for the calculation of structural response. Three-dimensional linear potential flow theory and global FE analysis are used for wave load and stress transfer function calculations. Then, the hot spots’ fatigue damage is calculated, considering various factors influencing spectral analysis, which includes cycle counting correction factors, wave scatter diagram, and the distribution coefficient of wave headings. A full-scale model fatigue test is used to investigate the fatigue behavior of the cross-deck structural detail. Using the fatigue test data, the curve characteristic of the cross-deck structural detail is produced. Finally, the trimaran cross-deck structural detail’s fatigue characteristics are summarized and the effects of the factors influencing spectral fatigue analysis are reported.

Vibration Analysis of Bracket for Vehicle Components

2018 ◽  
Author(s):  
Dongjoon Kim ◽  
Chulwoo Park ◽  
No-Cheol Park ◽  
Young-Pil Park
Keyword(s):  
Finite Element ◽  
Vibration Analysis ◽  
Element Model ◽  
Fatigue Analysis ◽  
Design Stage ◽  
Static Fatigue ◽  
Fe Model ◽  
Vehicle Components ◽  
External Forces ◽  
Dynamic Fatigue

As automobile is exposed to continuous external forces such as road noise and engine vibration, it is necessary to evaluate vehicle components’ vibration durability at the initial design stage. Fatigue failure is one of the frequent failure mechanism occurred in mechanical components when cyclic loading is applied to subject. Fatigue analysis can be classified into two types; quasi-static fatigue analysis dynamic fatigue analysis considering structural resonance. As the tested bracket’s first natural frequency existed in the requirement spec for vibration test (10∼50 Hz) so dynamic fatigue analysis should be performed. In this study, vibration analysis was carried out in advance of fatigue analysis. Improving design based on the experiments is inefficient and takes a lot of time and money, so finite element model was constructed. From single components to assembly, modal test was performed and verified the finite element (FE) model within 10% error. Also, boundary conditions were determined using beam elements. After FE model construction, vibration analysis was performed using harmonic analysis. The cause of the failure was analyzed based on simulation results.

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