Fatigue crack growth and fatigue life estimation of notched members in a short crack range

1998 ◽  
pp. 547-552 ◽  
Author(s):  
D. Kocańda ◽  
S. Kocańda ◽  
H. Tomaszek
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Short Crack ◽  
Life Estimation ◽  
Fatigue Life Estimation

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.

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.

Predicting Fatigue Crack Growth and Fatigue Life Under Variable Amplitude Loading

2010 ◽  
Vol 2010 (2) ◽  
pp. 37-51
Author(s):  
Michal Jasztal ◽  
Dorota Kocanda ◽  
Henryk Tomaszek
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Probabilistic Approach ◽  
Alloy Sheet ◽  
Load Spectrum ◽  
Variable Amplitude Loading ◽  
Variable Amplitude ◽  
Fatigue Life Estimation

Predicting Fatigue Crack Growth and Fatigue Life Under Variable Amplitude Loading A probabilistic approach to the description of fatigue crack growth and fatigue life estimation of a component subjected to variable amplitude loading is presented in the paper. The core of the model is a differential equation originated from the Paris formula. In order to consider the influence of overload-underload cycles existing in an exploitive load spectrum on crack growth rate for an aeronautical aluminum alloy sheet, the modified Willenborg retardation model was applied.

scholarly journals OBSERVATIONS ON FATIGUE CRACK GROWTH AND FATIGUE LIFE OF RIVETED LAP JOINTS

2012 ◽  
Vol 31 (3) ◽  
pp. 108
Author(s):  
Andrzej SKORUPA ◽  
Małgorzata SKORUPA ◽  
Tomasz MACHNIEWICZ ◽  
Andrzej KORBEL
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Lap Joints ◽  
Riveted Lap Joints

scholarly journals Influence of Pre-Stress Magnitude on Fatigue Crack Growth Behavior of Al-Alloy

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1267
Author(s):  
Chunguo Zhang ◽  
Weizhen Song ◽  
Qitao Wang ◽  
Wen Liu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Shot Peening ◽  
Fatigue Property ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Al Alloy ◽  
Fatigue Crack Growth Behavior

From tensile overload to shot peening, there have been many attempts to extend the fatigue properties of metals. A key challenge with the cold work processes is that it is hard to avoid generation of harmful effects (e.g., the increase of surface roughness caused by shot peening). Pre-stress has a positive effect on improving the fatigue property of metals, and it is expected to strength Al-alloy without introducing adverse factors. Four pre-stresses ranged from 120 to 183 MPa were incorporated in four cracked extended-compact tension specimens by application of different load based on the measured stress–strain curve. Fatigue crack growth behavior and fractured characteristic of the pre-stressed specimens were investigated systematically and were compared with those of an as-received specimen. The results show that the pre-stress ranged from 120 to 183 MPa significantly improved the fatigue resistance of Al-alloy by comparison with that of the as-received specimen. With increasing pre-stress, the fatigue life first increases, then decrease, and the specimen with pre-stress of 158 MPa has the longest fatigue life. For the manner of pre-stress, no adverse factor was observed for increasing fatigue property, and the induced pre-stress reduced gradually till to disappear during subsequent fatigue cycling.

Sign in / Sign up

Export Citation Format

Share Document