scholarly journals EXTENDING FATIGUE LIFE OF CRACKED OUT-OF-PLANE GUSSET BY ICR TREATMENT

2011 ◽  
Vol 28 (1) ◽  
pp. 21s-28s ◽  
Author(s):  
Toshiyuki ISHIKAWA ◽  
Kentaro YAMADA ◽  
Takumi KAKIICHI ◽  
Hui LI
Keyword(s):  
Fatigue Life ◽  
Out Of Plane

scholarly journals Correction: Wang et al. Generalized SCF Formula of Out-Of-Plane Gusset Welded Joints and Assessment of Fatigue Life Extension by Additional Weld. Materials 2021, 14, 1249

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2331
Author(s):  
Yixun Wang ◽  
Yuxiao Luo ◽  
Yuki Kotani ◽  
Seiichiro Tsutsumi
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
Life Extension ◽  
Out Of Plane

The authors wish to revise in the text of Appendix A, pages 19–21 [...]

scholarly journals Generalized SCF Formula of Out-Of-Plane Gusset Welded Joints and Assessment of Fatigue Life Extension by Additional Weld

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1249
Author(s):  
Yixun Wang ◽  
Yuxiao Luo ◽  
Yuki Kotani ◽  
Seiichiro Tsutsumi
Keyword(s):  
Fatigue Life ◽  
Fatigue Resistance ◽  
Welded Joints ◽  
Life Extension ◽  
Leg Length ◽  
Notch Stress ◽  
Out Of Plane ◽  
Weld Toe ◽  
Effective Notch Stress ◽  
Geometric Effects

The existing S-N curves by effective notch stress to assess the fatigue life of gusset welded joints can result in reduced accuracy due to the oversimplification of bead geometries. The present work proposes the parametric formulae of stress concentration factor (SCF) for as-welded gusset joints based on the spline model, by which the effective notch stress can be accurately calculated for fatigue resistance assessment. The spline model is also modified to make it applicable to the additional weld. The fatigue resistance of as-welded and additional-welded specimens is assessed considering the geometric effects and weld profiles. The results show that the error of SCFs by the proposed formulae is proven to be smaller than 5%. The additional weld can increase the fatigue life by as great as 9.4 times, mainly because the increasing weld toe radius and weld leg length lead to the smaller SCF. The proposed series of S-N curves, considering different SCFs, can be used to assess the welded joints with various geometric parameters and weld profiles.

scholarly journals Evaluation of fatigue life of thick CFRP laminates with toughened interlaminar layers in out-of-plane and in-plane transverse directions

2017 ◽  
Vol 83 (851) ◽  
pp. 16-00571-16-00571 ◽  
Author(s):  
Sen SEKI ◽  
Tomoki ARAI ◽  
Shinichiro FUKUSHIMA ◽  
Atsushi HOSOI ◽  
Yuzo FUJITA ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Cfrp Laminates ◽  
Plane Transverse ◽  
Out Of Plane

Numerical Methods for Interlink Stiffness Formulations and Parameters Sensitivity of Out-of-Plane Bending in Mooring Chains

2019 ◽  
Author(s):  
Ceasar Edward ◽  
Arun Kr. Dev
Keyword(s):  
Fatigue Life ◽  
Numerical Methods ◽  
Material Properties ◽  
Plastic Material ◽  
Numerical Models ◽  
Critical Role ◽  
Research Work ◽  
Non Linear ◽  
Out Of Plane ◽  
Vertical Displacements

Abstract Mooring components used for offshore floaters are conventionally designed only to resist axial loads with minimum resistance to bending loads. However, the unprecedented failure of four mooring lines of the Girassol Buoy followed by new modifications of similar buoys exposed the gaps in the existing methodology for failure assessment. The root cause of this failure was attributed to the critical role of out-of-plane (OPB) bending induced fatigue which reduced the fatigue life by 95%. The methodology to incorporate OPB fatigue for failure assessments involves a complex process due to numerous parameters required in the formulations and variability of mooring configurations. One of the most critical steps required to simplify methodology is the formulation of the interlink stiffness, contact stiffness and global stiffness of the chain segment. Currently, the interlink stiffness is derived from full-scale laboratory testing which is expensive and has limitations in generating data for a range of configurations. This paper focuses on producing the interlink stiffness using numerical simulations based on non-linear FE analysis to capture the complex interlink contacts mechanism at the mating surface, elastic-plastic material properties considering non-linear isotropic and non-linear kinematic behaviors during OPB response modes, and compare the numerical models based on available experimental data. The numerical model developed for this research are designed to replicate real case OPB scenarios which induces both rotation and vertical displacements at the mooring connection points. This is different from models studied so far that induces only vertical displacements to study OPB responses which produces conservative results. Further to this, an exhaustive analysis of the key OPB inducing parameters like chain diameter, types, pre-tension, instantaneous tensions, proof loading, residual stress, material properties, boundary condition etc. are required for understanding the underlying failure mechanism. This research also investigates the key OPB parameters and analyze their inter-dependencies, proportionalities and relative sensitivities to understand their overall contribution to OPB failures. This paper presents the first part of this research work which focuses on some of these key aspects to generate the simplified methodology using numerical methods. The findings of this research can be used to generate a database of interlink stiffness for application to a range of mooring configurations and develop mathematical formulations for carrying out a direct assessment of OPB fatigue in combination with tension-tension fatigue failures and proposes potential mechanisms for improving the fatigue life.

Investigations Into Fatigue of OPB Loaded Offshore Mooring Chains

2020 ◽  
Author(s):  
Gary H. Farrow ◽  
Simon Dimopoulos ◽  
Andrew A. Kilner
Keyword(s):  
Fatigue Life ◽  
First Principles ◽  
Complex Stress ◽  
Parent Material ◽  
Element Analysis ◽  
Butt Weld ◽  
System Integrity ◽  
Out Of Plane ◽  
Plane Bending ◽  
Fatigue Life Reduction

Abstract The Chain FEARS (Finite Element Analysis of Residual Strength) JIP developed a correlated FEA method for determining fatigue life of Tension-Tension (T-T) loaded offshore mooring chain. The developed first principles method incorporated the non-linear effects of proof loading, accounted for mean chain tension, accounted for material grade, employed a multi-axial fatigue method to account for complex stress fields within the chain, and was based on a parent material S-N curve. It was anticipated that this high fidelity approach could be applied more universally to successfully address a broader spectrum of emergent factors experienced in-field which have caused chain fatigue life reduction and adversely impacted mooring system integrity. These emergent factors include an array of chain degradation modes including; uniform, pitting and mega pitting corrosion; preferential butt weld corrosion; abrasive, contact and interlink wear; and load duties other than Tension-Tension (TT) such as Out-Of-Plane Bending (OPB), In-Plane-Bending (IPB) and Bending-Tension (BT). The objective of the investigations conducted by AMOG Consulting following completion of the Chain FEARS JIP research was to explore the extent to which the developed fatigue method could be applied more universally to address these emergent factors as they pertained to residual fatigue life. Application of the method identified a number of trends in fatigue performance for links subject to hawse pipe and fairlead interaction, and demonstrated good correlation against available guidance on fairlead performance and against OPB fatigue test data. The investigation confirms that the first principles FEA fatigue method can be applied more universally to successfully address a broader spectrum of emergent factors experienced in-field relating to fatigue life reduction.

Extending fatigue life of out-of-plane gusset joint by bonding CFRP plates under bending moment

2016 ◽  
Vol 16 (4) ◽  
pp. 1319-1327 ◽  
Author(s):  
Risa Matsumoto ◽  
Toshiyuki Ishikawa ◽  
Manabu Takemura ◽  
Yoshisato Hiratsuka ◽  
Hirotaka Kawano
Keyword(s):  
Fatigue Life ◽  
Bending Moment ◽  
Out Of Plane

Fatigue Design Methodology for Large Mooring Chains Subjected to Out-of-Plane Bending

2014 ◽  
Author(s):  
Tom Lassen ◽  
Jan Aarsnes ◽  
Einar Glomnes
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Barents Sea ◽  
Weather Condition ◽  
Design Criterion ◽  
Fatigue Damage Accumulation ◽  
Out Of Plane ◽  
Plane Bending ◽  
Mooring Chain

The present paper presents a fatigue life prediction method for chains subjected to tension and Out-of-Plane-Bending (OPB). The investigation was carried out on a high strength mooring chain segment with a diameter of 165 mm and a steel quality R5. Such chains are used in mooring systems for large Floating Production Storage and Offloading (FPSO) units in harsh weather condition. Due to the fact that the mooring chains are pre-tensioned the wave induced displacements will introduce secondary bending effects about the weak axis in the chain links, particularly in the bilge hang-off area. In such chains both conventional tension fatigue and fatigue damage accumulation due to Out-of-Plane-Bending (OPB) have to be analyzed. Results from full scale behavior tests, Finite Element Analyses and a case study with simulation of in-service loading are included in the present study. Finally, fatigue life predictions and an operational strategy are presented for a case study for a floater in the Barents Sea. With a target service life of 30 years, the endurance with respect to fatigue damage is a major design criterion for the mooring chain in this case.

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