scholarly journals Crack growth analysis and fatigue life estimation in the piston rod of a Kaplan hydro turbine

2018 ◽  
Vol 41 (11) ◽  
pp. 2402-2417 ◽  
Author(s):  
X. Liu ◽  
A. Presas ◽  
Y. Luo ◽  
Z. Wang
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Growth Analysis ◽  
Hydro Turbine ◽  
Life Estimation ◽  
Fatigue Life Estimation

scholarly journals A fatigue crack initiation and growth life estimation method in single-bolted connections

2019 ◽  
Vol 54 (2) ◽  
pp. 79-94 ◽  
Author(s):  
Arash P Jirandehi ◽  
TN Chakherlou
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Initiation ◽  
Crack Growth ◽  
Fatigue Crack Initiation ◽  
Multiaxial Fatigue ◽  
Estimation Accuracy ◽  
Life Estimation ◽  
Lower Error ◽  
Fatigue Life Estimation

Fatigue life estimation accuracy of mechanical parts and assemblies has always been the source of concern in different industries. The main contribution of this article lies in a study on the accuracy of different multiaxial fatigue criteria, proposing and investigating the accuracy of four optimized fatigue crack initiation life estimation methods—volume, weighted volume, surface and point, thereby improving the multiaxial fatigue life estimation accuracy. In order to achieve the goal, the fatigue lives of bolt clamped specimens, previously tested under defined experimental conditions, were estimated during fatigue crack initiation and fatigue crack growth and then summed together. In the fatigue crack initiation part, a code was written and used in the MATLAB software environment based on critical plane approach and the different multiaxial fatigue criteria. Besides the AFGROW software was utilized to estimate the crack growth share of fatigue life. Experimental and numerical results showed to be in agreement. Furthermore, detailed study and comparison of the results with the available experimental data showed that a combination of Smith–Watson–Topper approach and volume method results in lower error values, while a combination of Fatemi–Socie criterion and surface or point method presents estimated lives with lower error values. In addition, the numerical proposed procedure resulted in a good prediction of the location of fatigue crack initiation.

scholarly journals Survey of the crack growth approach for the fatigue life estimation of application-relevant rubbers

2016 ◽  
Author(s):  
Sandra Seichter ◽  
Vassiliki-Maria Archodoulaki ◽  
Thomas Koch ◽  
Wolfgang Fidi ◽  
Armin Holzner ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Growth Approach

The Fatigue Life Estimation Method From the Stress Concentration Region With Zero Defect: An Application to the Fatigue Crack Growth Simulation Code “FLARP” for the In-Plane Gusset Welded Joint

2004 ◽  
Author(s):  
Masahiro Toyosada ◽  
Koji Gotoh ◽  
Keitaro Konuma ◽  
Akira Sueda
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Opening ◽  
Simulation Code ◽  
Growth Simulation ◽  
Life Estimation ◽  
Crack Growth Simulation ◽  
Fatigue Life Estimation

In-plane gusset welded joints are very popular and used in many steel constructed structures. Fatigue life estimations for this type of joint have been performed by applying the fatigue crack growth simulation code “FLARP” developed by the authors. The fatigue crack shows the typical opening/closing behavior during fatigue crack growth. The plastic deformed layer in the crack wake, which represents the loading history indirectly, contributes to the behavior. The consideration of crack closure is essential in the estimation of the fatigue life. FLARP enables the quantitative simulation of the fatigue crack opening/closing. By considering the cyclic plastic behavior ahead of a fatigue crack tip, the improved effective stress intensity factor range (ΔKRPG) to denote the fatigue crack propagation law, which is formulated by replacing the crack opening load with the Retensile Plastic zone Generating load (RPG load), was defined. ΔKRPG is adopted as the parameter for the fatigue life estimation by FLARP. The validity of the fatigue life estimation by FLARP is confirmed by comparing the estimated S-N curves with the experimental results for the in-plane gusset welded joints.

Improvement of Pipeline Fatigue Life Estimation

2016 ◽  
Author(s):  
Sanjay Tiku ◽  
Aaron Dinovitzer ◽  
Vlad Semiga ◽  
Mark Piazza ◽  
Tom Jones
Keyword(s):  
Numerical Simulation ◽  
Growth Rate ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Life Estimation ◽  
Fatigue Life Estimation

Fracture mechanics methodologies for calculating fatigue lives have been successfully applied by pipeline operators to estimate integrity reassessment intervals. Their application in the definition of pipeline system fatigue lives has been overly conservative in actual practice. The source and magnitude of the conservatism inherent in the calculated fatigue life estimates needs to be identified so operators have a better indicator of when reassessments should take place. The pipe life estimation is especially critical for Electric Resistance Weld (ERW) and Electric Flash Weld (EFW) pipeline systems with longitudinally oriented defects. Prior work on improving fatigue life was initiated through studies completed by Pipeline Research Council International, Inc. (PRCI) to evaluate the sources of differences between fatigue life estimates produced by industry fatigue analysis software and different metallurgists. Two significant sources of conservatism in the fatigue life estimation process were identified: the fatigue crack growth rate (da/dN) and the bulging correction factor applied to axial surface flaws. The experimental and numerical simulation techniques considering the impact of these factors on rate of fatigue crack growth of pipeline axially oriented defects are described in this paper. Finite element modeling was used to simulate pipe bulging in the presence of axial flaws. The effect of the pipe thickness, diameter and flaw geometry was compared with treatments included in existing defect assessment standards. The results illustrate that for longer and deeper flaws existing treatments over represent the local bending due to pipe wall bulging. This results in unnecessarily conservative (shorter) fatigue life estimates. The crack growth rate (da/dN) was measured in a compact tension specimen material fatigue testing program. The test results included a range of ERW and EFW pipe materials with varying vintages and grades. The measured fatigue crack growth rate for the materials tested was found to be lower than that recommended by existing industry standards. This adds to the over conservatism of current approaches. The numerical simulation and materials testing results and related recommendations presented in this paper are compared to existing codified treatments to quantify the level of conservatism inherent in the current state of practice. Recommendations are provided to enhance the precision and better manage conservatism in fatigue crack growth rate calculations. Increased accuracy serves to improve integrity management and would be of interest to pipeline operators, consultants and regulators.

Fatigue life estimation of subsurface cracks based on crack growth rates measured in a vacuum environment

2019 ◽  
Vol 2019 (0) ◽  
pp. PS23
Author(s):  
Sourav Kumar MODI ◽  
Paras MEHENDIRATTA ◽  
Takuma TSUKAGOSHI ◽  
Takashi NAKAMURA ◽  
Nao FUJIMURA ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Crack Growth ◽  
Growth Rates ◽  
Life Estimation ◽  
Subsurface Cracks ◽  
Fatigue Life Estimation ◽  
Crack Growth Rates

Assessment of Geometry Correction Functions of Tanker Knuckle Details Based on Fatigue Tests and Finite-Element Analysis

2003 ◽  
Vol 126 (3) ◽  
pp. 220-226 ◽  
Author(s):  
Y. Garbatov ◽  
S. Rudan ◽  
C. Guedes Soares
Keyword(s):  
Finite Element Analysis ◽  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Correction Function ◽  
Element Analysis ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Geometry Correction

The paper analyzes the fatigue crack growth of knuckle detail typical of tankers. An approach for evaluation of the fatigue life based on fracture mechanics is presented, where a Paris-Erdogan crack-growth law is applied. A geometry correction function is determined from fatigue test data. A closed-form equation is proposed for fatigue life estimation. The results obtained from a fatigue test and the calculated fatigue lives are compared.

Assessment of Geometry Correction Functions of Tanker Knuckle Details Based on Fatigue Tests and Finite Element Analysis

2002 ◽  
Author(s):  
Y. Garbatov ◽  
S. Rudan ◽  
C. Guedes Soares
Keyword(s):  
Finite Element Analysis ◽  
Fatigue Life ◽  
Crack Growth ◽  
Fatigue Test ◽  
Fatigue Tests ◽  
Correction Function ◽  
Element Analysis ◽  
Life Estimation ◽  
Fatigue Life Estimation ◽  
Geometry Correction

The paper analyses the fatigue crack growth of knuckle detail typical of tankers. An approach for evaluation of the fatigue life based on fracture mechanics is presented, where a Paris-Erdogan crack-growth law is applied. A geometry correction function is determined from fatigue test data. A closed-form equation is proposed for fatigue life estimation. The results obtained from a fatigue test and the calculated fatigue lives are compared.

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