scholarly journals A Study on the Fatigue Life Assessment for Load-carrying Fillet Welded Joints using Stress Intensity Factor

2008 ◽  
Vol 26 (6) ◽  
pp. 97-102 ◽  
Author(s):  
Myung-Hyun Kim ◽  
Sung-Won Kang ◽  
Hyoung-Rae Kim
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Welded Joints ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Load Carrying

scholarly journals Mapping of scatter in fatigue life assessment of welded structures—a round-robin study

2021 ◽  
Author(s):  
Gustav Hultgren ◽  
Mansoor Khurshid ◽  
Peter Haglund ◽  
Zuheir Barsoum
Keyword(s):  
Fatigue Life ◽  
Round Robin ◽  
Life Assessment ◽  
Fatigue Life Assessment ◽  
Fatigue Life Estimation ◽  
Box Structures ◽  
Load Carrying ◽  
Local Stresses ◽  
Sources Of Variation ◽  
Global And Local

AbstractA round-robin study has been carried out within a national project in Sweden with the addition of an international participant, where several industrial partners and universities are participating. The project aims to identify variation and sources of variation in welding production, map scatter in fatigue life estimation, and define and develop concepts to reduce these, in all steps of product development. The participating organisations were asked to carry out fatigue life assessment of welded box structures, which is a component in load-carrying structures. The estimations of fatigue life have also been compared with fatigue test results. Detailed drawings, loads and material data were also given to the participants. The participants were supposed to use assessment methods based on global and local stresses using the design codes or recommendations they currently use in-house. Differences were identified between both methods and participants using the same codes/recommendations. Applicability and conditions from the cases in the codes were also identified to be differently evaluated between the participants. It could be concluded that for the applied cases the nominal stress method often overestimated the fatigue life and had a high scatter in the estimations by different participants. The effective notch method is conservative in comparison to the life of tested components with little scatter between the results derived by the participants.

Equivalent crack approach for fatigue life assessment of welded joints

2015 ◽  
Vol 149 ◽  
pp. 144-155 ◽  
Author(s):  
Eeva Mikkola ◽  
Yukitaka Murakami ◽  
Gary Marquis
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
Life Assessment ◽  
Fatigue Life Assessment

scholarly journals Effect of Pre-Corrosion Pits on Residual Fatigue Life for 42CrMo Steel

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2130 ◽  
Author(s):  
Dezheng Liu ◽  
Yan Li ◽  
Xiangdong Xie ◽  
Jing Zhao
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Research Work ◽  
Residual Fatigue Life ◽  
42Crmo Steel ◽  
Regression Formula ◽  
Residual Fatigue ◽  
Corrosion Pits

The effect of pre-corrosion pits on residual fatigue life for the 42CrMo steel (American grade: AISI 4140) is investigated using the accelerated pre-corrosion specimen in the saline environment. Different pre-corroded times are used for the specimens, and fatigue tests with different loads are then carried out on specimens. The pre-corrosion fatigue life is studied, and the fatigue fracture surfaces are examined by a surface profiler and a scanning electron microscope (SEM) to identify the crack nucleation sites and to determine the size and geometry of corrosion pits. Moreover, the stress intensity factor varying with corrosion pits in different size parameters is analyzed based on finite element (FE) software ABAQUS to derive the regression formula of the stress intensity factor. Subsequently, by integrating the regression formula with the Paris formula, the residual fatigue life is predicted and compared with experimental results, and the relationship of the stress intensity factor, pit depth, and residual fatigue life are given under different corrosion degrees. The fatigue life predicted by the coupled formula agrees well with experiment results. It is observed from the SEM images that higher stress amplitude and longer pre-corroded time can significantly decrease the residual fatigue life of the steel. Additionally, the research work has brought about the discovery that the rate of crack extension accelerates when the crack length increases. The research in this paper also demonstrates that the corrosion pit size can be used as a damage index to assess the residual fatigue life.

Fatigue Damage Analysis on Crack Growth and Fatigue Life of Welded Bridge Members with Initial Crack

2006 ◽  
Vol 324-325 ◽  
pp. 251-254 ◽  
Author(s):  
Tai Quan Zhou ◽  
Tommy Hung Tin Chan ◽  
Yuan Hua
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Damage ◽  
Initial Crack ◽  
Traffic Loading

The behavior of crack growth with a view to fatigue damage accumulation on the tip of cracks is discussed. Fatigue life of welded components with initial crack in bridges under traffic loading is investigated. The study is presented in two parts. Firstly, a new model of fatigue crack growth for welded bridge member under traffic loading is presented. And the calculate method of the stress intensity factor necessary for evaluation of the fatigue life of welded bridge members with cracks is discussed. Based on the concept of continuum damage accumulated on the tip of fatigue cracks, the fatigue damage law suitable for steel bridge member under traffic loading is modified to consider the crack growth. The proposed fatigue crack growth can describe the relationship between the cracking count rate and the effective stress intensity factor. The proposed fatigue crack growth model is then applied to calculate the crack growth and the fatigue life of two types of welded components with fatigue experimental results. The stress intensity factors are modified by the factor of geometric shape for the welded components in order to reflect the influence of the welding type and geometry on the stress intensity factor. The calculated and measured fatigue lives are generally in good agreement, at some of the initial conditions of cracking, for a welded component widely used in steel bridges.

Fatigue Growth Behaviour for Surface Crack in Welded Joints Under Combined Tension and Bending Stresses

2006 ◽  
Author(s):  
Jian-Ping Zhao ◽  
Wen-Long Huang
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Growth ◽  
Surface Crack ◽  
Welded Joints ◽  
Stress Intensity Factor Range ◽  
Growth Behaviour ◽  
Bending Stresses ◽  
The Relationship

The fatigue growth behaviour for surface crack in welded joints under combined tension and bending stresses is studied by fatigue crack growth tests of 16MnR steel in bow specimens. In this present paper the Newman-Raju empirical equation was used for the stress intensity factor of a surface crack. The experimental results show that the Paris’ relationship between crack growth rate and stress intensity factor range under tension and bending fatigue stresses is still valid, and the relationship between the Paris’ coefficients Ca and Cc can be represented as Cc = (0.89)mCa.

Fracture Mechanics Fatigue Evaluation of a Flowline Clamp Connector Using Finite Element Modeling of a Crack

2019 ◽  
Author(s):  
Curtis Sifford ◽  
Ali Shirani
Keyword(s):  
Finite Element Analysis ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Pressure Vessel ◽  
Crack Tip ◽  
Element Analysis

Abstract This paper presents the application of the rules from ASME Section VIII, Division 3 of the ASME Boiler and Pressure Vessel Code for a fracture mechanics evaluation to determine the damage tolerance and fatigue life of a flowline clamp connector. The guidelines from API 579-1 / ASME FFS-1 Fitness-For-Service for the stress analysis of a crack-like flaw have been considered for this assessment. The crack tip is modeled using a refined mesh around the crack tip that is referred to as a focused mesh approach in API 579-1 / ASME FFS-1. The driving force method is used as an alternative to the failure assessment diagram method to account for the influence of crack tip plasticity. The J integral is determined using elastic-plastic finite element analysis and converted to an equivalent stress intensity factor to be compared to the fracture toughness of the material. The fatigue life is calculated using the Paris Law equation and the stress intensity factor calculated from the finite element analysis. The allowable number of design cycles is determined using the safety factors required from Division 3 of the ASME Pressure Vessel Code.

Fracture Mechanics Fatigue Evaluation of a Flowline Clamp Connector Using Finite Element Modeling of a Crack

2018 ◽  
Author(s):  
Curtis Sifford ◽  
Ali Shirani
Keyword(s):  
Finite Element Analysis ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Fracture Mechanics ◽  
Intensity Factor ◽  
Pressure Vessel ◽  
Crack Tip ◽  
Element Analysis

This paper presents the application of the rules from ASME Section VIII, Division 3 of the ASME Boiler and Pressure Vessel Code for a fracture mechanics evaluation to determine the damage tolerance and fatigue life of a flowline clamp connector. The guidelines from API 579-1 / ASME FFS-1 Fitness-For-Service for the stress analysis of a crack-like flaw have been considered for this assessment. The crack tip is modeled using a refined mesh around the crack tip that is referred to as a focused mesh approach in API 579-1 / ASME FFS-1. The driving force method is used as an alternative to the failure assessment diagram method to account for the influence of crack tip plasticity. The J integral is determined using elastic-plastic finite element analysis and converted to an equivalent stress intensity factor to be compared to the fracture toughness of the material. The fatigue life is calculated using the Paris Law equation and the stress intensity factor calculated from the finite element analysis. The allowable number of design cycles is determined using the safety factors required from Division 3 of the ASME Pressure Vessel Code.

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