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.

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].

Fatigue Assessment of “Corroded” Mooring Chain

2019 ◽  
Author(s):  
David A. Baker ◽  
Zhen Li ◽  
Sue Wang ◽  
Xiying Zhang ◽  
Yunliang Shao ◽  
...  
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Fatigue Test ◽  
Best Practice ◽  
Fatigue Testing ◽  
Fatigue Tests ◽  
Element Analysis ◽  
Cycle Count ◽  
Remaining Fatigue Life ◽  
Mooring Chain

Abstract Assessment of corroded mooring chain for continued service is a challenging task faced by industry. Current best practice relies heavily on qualitative inspection information collected during inspection campaign. There has been little investigation into this practice and whether it is an appropriate technique or can be improved. To address this issue, the Fatigue of Corroded Mooring Chains (FoCCs) Joint Industry Project (JIP), initiated in 2016 with fifteen (15) participating organizations, including oil majors, chain manufactures, consulting firms, and classification societies, to examine assessment methods for evaluating remaining fatigue life. JIP teams were formed to progress fatigue testing and finite element objectives. One such team, comprised of ExxonMobil, ABS and Asian Star Anchor Chain, has performed an additional series of fatigue tests beyond the core JIP work effort. A fatigue test was conducted to 1) demonstrate the utility of finite element analysis in the assessment of fatigue life and 2) demonstrate performance of simulated damage. This unique fatigue test program was conducted on mooring chain with manufactured “corrosion pits” of different dimensions. All chain surface features were digitally recorded and converted into finite element models. These models were subsequently analyzed to compare with test results — both cycle count and failure location. This paper presents the findings from these fatigue tests and finite element analyses and how they can be utilized for assessment of remaining fatigue life.

Behaviour of Axially Loaded Composite Wall Panel by Using Finite Element Analysis

2015 ◽  
Vol 815 ◽  
pp. 49-53
Author(s):  
Nur Fitriah Isa ◽  
Mohd Zulham Affandi Mohd Zahid ◽  
Liyana Ahmad Sofri ◽  
Norrazman Zaiha Zainol ◽  
Muhammad Azizi Azizan ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Composite Structures ◽  
Element Analysis ◽  
Steel Sheets ◽  
Linear Behavior ◽  
Non Linear ◽  
Composite Wall ◽  
Experimental Values ◽  
Civil Engineering Infrastructure

In order to promote the efficient use of composite materials in civil engineering infrastructure, effort is being directed at the development of design criteria for composite structures. Insofar as design with regard to behavior is concerned, it is well known that a key step is to investigate the influence of geometric differences on the non-linear behavior of the panels. One possible approach is to use the validated numerical model based on the non-linear finite element analysis (FEA). The validation of the composite panel’s element using Trim-deck and Span-deck steel sheets under axial load shows that the present results have very good agreement with experimental references. The developed finite element (FE) models are found to reasonably simulate load-displacement response, stress condition, giving percentage of differences below than 15% compared to the experimental values. Trim-deck design provides better axial resistance than Span-deck. More concrete in between due to larger area of contact is the factor that contributes to its resistance.

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

Specimen positioning effect on microshear test: Non-linear finite element analysis

2012 ◽  
Vol 28 ◽  
pp. e15-e16
Author(s):  
L.H.A. Raposo ◽  
L.C.M. Dantas ◽  
T.A. Xavier ◽  
A.G. Pereira ◽  
A. Versluis ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Element Analysis ◽  
Linear Finite Element ◽  
Non Linear

Dynamic Loading Approach for Structural Evaluation of Ultra Large Container Carriers

2005 ◽  
Author(s):  
Bill Shi ◽  
Donald Liu ◽  
Christopher Wiernicki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Dynamic Loading ◽  
Impact Load ◽  
Failure Mechanisms ◽  
Direct Calculation ◽  
Element Analysis ◽  
Design Philosophy ◽  
Non Linear ◽  
Large Container

The emerging global economic needs are driving the designs for the next generation of ocean going vessels. Current ultra-large container carrier (10,000 TEU plus) designs are considerably larger and more complex than any currently in service. Proper and rational classification assessment requires that first principles based direct calculation methods be used to augment the standard classification review. The design philosophy behind the ABS Dynamic Loading Approach enables comprehensive identification of potential failure mechanisms. The scope of the necessary engineering assessment encompass full-ship finite element analysis under non-linear sea loads, spectral fatigue analysis, finite element lashing analysis, free and forced vibration analysis, and transient and impact load analysis. This paper describes key aspects of the DLA design philosophy such as non-linear sea loads, load combinations, various applications derived from full-ship finite element analysis. Several examples are given to highlight some critical failure mechanisms to be considered for ultra-large container carriers.

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