Review and Comparison of Collated Offshore Mooring Chain Fatigue Test Data

2019 ◽  
Author(s):  
Gary H. Farrow ◽  
Andrew E. Potts ◽  
Eric Jal ◽  
Nicholas D’Arcy Evans ◽  
Andrew A. Kilner
Keyword(s):  
Finite Element Analysis ◽  
Fatigue Test ◽  
Test Data ◽  
Element Analysis ◽  
Chain Link ◽  
The Mean ◽  
Fatigue Endurance ◽  
Current Code ◽  
Mooring Chain ◽  
Chain Type

Abstract The first phase of the Chain FEARS (Finite Element Analysis of Residual Strength) Joint Industry Project (JIP) aimed to develop guidance for the determination of a rational discard criteria for mooring chains subject to severe pitting corrosion which, based on current code requirements, would otherwise require immediate removal and replacement. Critical to the ability to evaluate the residual fatigue life of a degraded chain, is to have an accurate estimate of the chain in its as-new condition, thereby providing a benchmark for any loss in fatigue life associated with severe corrosion or wear. A large collection of fatigue test data was collated for comparison and to establish underlying trends in as-new mooring chain fatigue response, and a non-linear multi-axial Finite Element Analysis (FEA) fatigue assessment method was developed to correlate against available as-new chain link fatigue test data and underlying failure trends [1,2] as part of the JIP achieving this critical requirement. This study sought through collation and review of available fatigue test data to: • Identify relationships between chain fatigue performance and the key input parameters of chain type, grade and environmental conditions. • Compare and validate the fatigue test data against the current Code formulations for chain fatigue endurance. • Determine chain nominal stress S-N fatigue endurance curves against which to validate a numerical model developed as part of the Chain FEARS JIP for the assessment of as-new chain link fatigue endurance. The collated fatigue data was separated into groups associated with offshore mooring chain type (i.e. stud and studless), grade (i.e. ORQ, R3, R4 and R5) and environmental conditions (i.e. free corrosion in seawater and in-air) for review. Good correlation occurred between the two standard deviation lower bound of the mean curves and current Code formulation design curves. The mean curves of the collated fatigue test data were considered representative of the overall fatigue performance of chain links and as such formed a good basis for subsequent development and the validation of an FEA model for the assessment of chain fatigue endurance [1,2].

Development of a New, Correlated FEA Method of Assessing Mooring Chain Fatigue

2019 ◽  
Author(s):  
Gary H. Farrow ◽  
Andrew E. Potts ◽  
Andrew A. Kilner ◽  
Phillip P. Kurts ◽  
Simon Dimopoulos ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Test Data ◽  
Linear Chain ◽  
Element Analysis ◽  
Chain Link ◽  
Non Linear ◽  
Mooring Chain

Abstract The first phase of the Chain FEARS (Finite Element Analysis of Residual Strength) Joint Industry Project (JIP) aimed to develop guidance for the determination of a rational discard criteria for mooring chains subject to severe pitting corrosion which, based on current code requirements, would otherwise require immediate removal and replacement. Critical to the ability to evaluate the residual fatigue life of a degraded chain, is to have an accurate estimate of the chain in its as-new condition, thereby providing a benchmark for any loss in fatigue life associated with severe corrosion or wear. A large collection of fatigue test data was collated for comparison and to establish underlying trends in as-new mooring chain fatigue response. A non-linear multi-axial Finite Element Analysis (FEA) fatigue assessment method was developed to correlate against available as-new chain link fatigue test data and underlying failure trends as part of the JIP achieving this critical requirement. It was established that the linear FEA fatigue method currently employed in the industry is too simplistic and does not correlate with the fatigue test data, whereas an alternative method of assessing fatigue based on FEA, developed with respect to the DNV B1 material curve, correlates well with the available physical fatigue test data. The FEA method uses a non-linear chain link FEA and multi-axial stress fatigue calculation method to determine an equivalent Stress Magnification Factor (SMF). This method achieves good correlation of predicted utilisations and associated cycles-to-failure with fatigue test data and in respect of critical locations with evidenced failure locations. The method of equivalent SMF calculation accounted for the significant effects on fatigue performance including proof load induced residual stress, mean stress levels and the increase in material fatigue endurance associated with increased steel UTS (i.e. increased offshore mooring chain grade). The analytical method developed in this study achieved a high degree of correlation with as-new chain fatigue test data, and should enable the accurate prediction of fatigue stresses around a link and in particular for irregular geometry associated with corrosion degraded chain links.

Investigations Into Fatigue Performance of Offshore Mooring Chains

2017 ◽  
Author(s):  
Gary H. Farrow ◽  
Andrew E. Potts ◽  
Daniel G. Washington
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Test Data ◽  
Assessment Method ◽  
Accurate Estimate ◽  
Element Analysis ◽  
Factors Influencing ◽  
Non Linear

The Chain Finite Element Analysis of Residual Strength Joint Industry Project (Chain FEARS JIP) aimed to develop guidance for the determination of a rational discard criteria for mooring chains subject to severe pitting corrosion which would otherwise require immediate removal and replacement. Critical to the ability to evaluate the residual fatigue life of a degraded chain, is to have an accurate estimate of the chain in its as-new condition, thereby providing a benchmark for any loss in fatigue life associated with severe corrosion or wear. A non-linear multi-axial Finite Element Analysis (FEA) fatigue assessment method was developed and correlated against available fatigue test data as part of the JIP achieving this critical requirement. The development of this correlated methodology necessitated a review of: • The available mooring chain fatigue test data, to identify the factors influencing chain fatigue life and failure location. • FEA fatigue methodologies currently employed in the industry. • Current Class Rules relating to fatigue estimation. • The influence of material, manufacturing and operational factors on chain fatigue life. It was established that while the linear FEA fatigue method currently employed in the industry does not correlate with the fatigue test data, the non-linear multi-axial FEA fatigue method developed in the JIP afforded good correlation with test data. It was also demonstrated that the magnitude of mean chain tension and inconsistency in proof loading, as a consequence of the inconsistency in Class Minimum Break Load (MBL) specification, and with respect to chain size and the varying material ductility of steel grades, effects fatigue life. The identified inconsistency in the proofing indicates a likely inconsistency in conservatism embodied in the Class Rules fatigue formulation. Consequently it is possible that chains of certain size and grade may have significantly less fatigue life than anticipated by Class. Further work is recommended to establish a more rational proof load specification and to develop an alternative Class Rules fatigue formulation accounting for the identified factors influencing fatigue.

Investigating the Effect of Weight Reduction of Rod-End in Drag-Link Product with Finite Element Analysis, Fatigue Test, and a Case Study

2020 ◽  
Vol 21 (2) ◽  
pp. 513-518
Author(s):  
Erinç Uludamar ◽  
Mustafa Taş ◽  
Sami Gökberk Biçer ◽  
Cihan Yıldırım ◽  
Ebru Aykut Yıldırım ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Test ◽  
Weight Reduction ◽  
Element Analysis ◽  
Drag Link

Influence of Construction Procedures on the Liner and Stress of a PC Continuous Beam Bridge

2010 ◽  
Vol 121-122 ◽  
pp. 162-167
Author(s):  
Hu Cheng ◽  
Guo Xuan
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Test Data ◽  
Significant Influence ◽  
Continuous Beam ◽  
Element Analysis ◽  
Continuous Beam Bridge ◽  
Cantilever Construction ◽  
Beam Bridge

During the construction of a bridge, the construction procedures may change from the originally designed procedures due to some reasons like the weather. In this paper, the influence of construction procedures on the liner and stress is investigated for a prestressed continuous beam bridge with three spans. Finite element analysis indicated that construction procedures have great impact on the liner control and they affect the middle span and side span differently. Although different sets of construction procedures cause different stress at corresponding construction stages after the cantilever construction is finished, they have no significant influence on the stress of the finally built bridge. Test data agreed with finite element analysis. It is thus the influence of construction procedures on bridge liner control should not be neglected.

scholarly journals Analysis of fatigue test data of retrieved mooring chain links subject to pitting corrosion

2022 ◽  
Vol 81 ◽  
pp. 103119
Author(s):  
Jorge Mendoza ◽  
Per J. Haagensen ◽  
Jochen Köhler
Keyword(s):  
Fatigue Test ◽  
Test Data ◽  
Pitting Corrosion ◽  
Chain Links ◽  
Mooring Chain

New Triaxial Connection Safety Factor for Tubular Design

2021 ◽  
pp. 1-11
Author(s):  
Malcolm A. Goodman
Keyword(s):  
Finite Element Analysis ◽  
Safety Factor ◽  
American Petroleum Institute ◽  
Von Mises Stress ◽  
Element Analysis ◽  
Threaded Connections ◽  
Shear Component ◽  
Physical Tests ◽  
The Mean ◽  
Von Mises

Summary The American Petroleum Institute (API) equation for internal leak of API connections is uniaxial because it ignores axial force and external backup pressure. The ISO 13679 (2002) standard for qualification of premium connections is biaxial at best. It includes tension/compression but ignores backup pressure for both internal and external leak tests. For tubular design, this paper introduces a new fully triaxial safety factor for threaded connections with dependence on thread shear and hydrostatic pressure. Triaxial hydrostatic behavior is modeled with the mean normal stress, and thread shear behavior is modeled with the shear component of the von Mises stress. A leak line for use like the pipe body ellipse is proposed for quick leak assessment. Leak ratings and correlation with finite element analysis (FEA) results are presented for an example case of a 7-in.35-ppf N80 long-thread-casing (LTC) connection. The new triaxial safety factor with two connection constants applies to all types of threaded connections, including tubing, casing, and drillpipe, so long as the two constants are evaluated with appropriate but simple physical tests.

Design of a Dynamic External Finger Fixator

2016 ◽  
Vol 10 (4) ◽  
Author(s):  
May M. Youssef ◽  
Duncan E. T. Shepherd ◽  
O. Garth Titley
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Mechanical Testing ◽  
Stainless Steel 316L ◽  
Element Analysis ◽  
Polyether Ether Ketone ◽  
The Finite Element Analysis ◽  
Ether Ketone ◽  
Improved Design ◽  
Fatigue Endurance

This paper describes an improved design of an external fixator. The new fixator comprises 13 parts which are assembled together. The proposed device materials consist of polyether ether-ketone (PEEK) and stainless steel 316L. The design was subjected to finite-element analysis, and a working model was manufactured and subjected to cyclic mechanical testing. The finite-element analysis showed that the maximum stress was 242.9 MPa and this was less than the yield strength and the fatigue endurance limits for the selected materials. Mechanical testing showed that testing reached run-out of 170,000 cycles with no cracks or damage visible in the device parts.

scholarly journals Finite Element Analysis with COMSOL Code for Air Flow and Thermal Convection in Sealed Attic Spaces with Experimental Validation

2015 ◽  
Vol 12 (1) ◽  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Aspect Ratio ◽  
Thermal Convection ◽  
Air Flow ◽  
Dimensional System ◽  
Computational Domain ◽  
Element Analysis ◽  
The Mean ◽  
Air Flows

The scope of the present paper is concerned with the numerical prediction of the confined air flow characteristics and thermal convection patterns in sealed attic spaces in roofs with upper inverted V-shapes and horizontal suspended ceilings of conventional houses and buildings. For these isosceles triangular cavities, two relevant cases involve prescribed wall temperatures wherein the bottom base wall is cooled/heated and the upper two inclined walls are symmetrically heated/cooled during the summer and winter seasons. Based on finite element analysis, the COMSOL code is implemented to perform numerical solutions of the two-dimensional system of coupled NavierStokesBoussinesq and energy equations. The computational domain is made coincident with the physical domain to handle potential non-symmetric velocities and non-symmetric temperatures that may occur when exposed to vigorous air flows. The numerical solution via finite elements provides the two velocity fields u (x, y), v (x, y) and the temperature field T (x, y) for the confined air flows. Overall, the target design quantity is the mean wall heat fluxes w q varying with the attic aspect ratio and the temperature difference at two opposing walls. The predicted w q values match the experimental measurements for the two distinct cases related to summer and winter seasons. At the end, comprehensive correlation equations are constructed for the quantification of the mean Nusselt number in terms of the Grashof number and the attic aspect ratio, which could be used in building science research.

scholarly journals Finite Element Analysis Generates an Increasing Interest in Dental Research: A Bibliometric Study

2016 ◽  
Vol 10 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Abdoulaziz Diarra ◽  
Vagan Mushegyan ◽  
Adrien Naveau
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Elements ◽  
Impact Factor ◽  
Web Of Science ◽  
Bibliometric Study ◽  
Element Analysis ◽  
Dental Research ◽  
Thomson Reuters ◽  
The Mean

Purpose:The purpose was to provide a longitudinal overview of published studies that use finite element analysis in dental research, by using the SCI-expanded database of Web of Science®(Thomson Reuters).Material and Methods:Eighty publications from 1999-2000 and 473 from 2009-2010 were retrieved. This literature grew faster than the overall dental literature. The number of publishing countries doubled. The main journals were American or English, and dealt with implantology. For the top 10 journals publishing dental finite element papers, the mean impact factor increased by 75% during the decade.Results:Finite elements generate an increasing interest from dental authors and publishers worldwide.

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