scholarly journals Evaluation of Fatigue Crack Growth Rate on the Surface of Steel Members Using COD(Crack Opening Displacement) Measurement

2011 ◽  
Vol 15 (2) ◽  
pp. 179-188
Author(s):  
Kwang Jin Kim ◽  
In Tae Kim
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Opening Displacement ◽  
Fatigue Crack Growth Rate ◽  
Crack Opening ◽  
Opening Displacement ◽  
Steel Members

Investigation of the fatigue crack growth rate in heatresistant nickel alloys

2021 ◽  
pp. 48-63
Author(s):  
I. A. Khodinev ◽  
S. A. Monin ◽  
P. V. Ryzhkov
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Elevated Temperatures ◽  
Crack Opening ◽  
Cyclic Crack Resistance ◽  
Inconel 625

The results of tests on the FCGR (fatigue crack growth rate) of compact specimens of eccentric tension using a crack opening (COD) sensor under conditions of an asymmetric loading cycle R=0.1 at room and elevated temperatures are presented. The relationship between the conditions of force loading of preliminary growth of the initial fatigue crack is considered. The values of the effective stress intensity factor Keff were obtained, which is an important estimate for interpreting the observed character of crack growth. A comparison of the properties of the cyclic crack resistance of the VZh175-ID alloy with the properties of foreign analogues Rene 88DT, Inconel 625 SLM and domestic ones - EP741NP, EK151-ID is presented. The influence of the test temperature on the growth rate is shown. The hypothesis about the linear dependence of the parameters of the Paris equation is tested.

Fatigue Crack Growth Rate Characteristics of Laser Shock Peened Ti-6Al-4V

1999 ◽  
Vol 121 (3) ◽  
pp. 321-329 ◽  
Author(s):  
John J. Ruschau ◽  
Reji John ◽  
Steven R. Thompson ◽  
Theodore Nicholas
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Crack Opening ◽  
Laser Shock ◽  
Effective Stress Intensity Range ◽  
Stress Ratios

The fatigue crack growth rate (FCGR) characteristics of Laser Shock Peened (LSP) titanium 6Al-4V were examined and compared to those of unprocessed material. The FCGR resistance of LSP processed material tested at low stress ratios (R) is shown to be significantly greater than for unprocessed, baseline material. The increased damage tolerance can be attributed to the large residual compressive stresses generated by the LSP process. Differences in the growth rate behavior due to LSP can be accounted for by using the closure corrected effective stress intensity range, ΔKeff, which takes into account only the portion of loading above the crack opening load. The rationale of using ΔKeff is also demonstrated through fractographic investigations.

Influence of Strength Mismatch and Weld Residual Stress on Fatigue Crack Growth Behavior for Pipeline Steel Including Closure Effects

2010 ◽  
Author(s):  
Diego Felipe Sarzosa Burgos ◽  
Claudio Ruggieri
Keyword(s):  
Residual Stress ◽  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Fatigue Crack Growth Rate ◽  
Crack Opening ◽  
Tensile Stresses

The integrity of mechanical components, particularly when they undergo significant fatigue damage for the duration of operating life, can be strongly influenced by the presence of residual stress fields and mechanical heterogeneity. Premature closure of crack flanks greatly influences fatigue crack growth rate. To estimate the crack closure in any welded structure, the residual stresses and strength mismatch in the vicinity of the crack tip should be considered. Extensive elastic-plastic finite element analyses have been carried out to investigate detailed crack closure behavior in heterogeneous compact tension (CT) specimens with three levels of weld strength mismatch and imposed uniform tensile residual stress field. The restriction on uncraked ligament imposed by E-647 is rather unconservative because it does not ensure linear elastic behavior at the crack tip. A relationship between the crack opening loads, the mismatch level and maximum applied stress intensity factor was obtained for small scale yielding (SSY) condition. This equation shall be used for fast estimations of closure effects for welding joints. A homogeneous, soft material has the largest crack opening loads, while a heterogeneous material with 50% overmatch conditions has the smallest opening load under SSY condition. Residual tensile stresses have detrimental effects on the fatigue resistance of the material. On average, residual tensile stresses, with magnitude equal to 0.5σy of the base metal, increase the Fatigue Crack Growth Rate (FCGR) by 40% when compared to the case without residual stress under SSY condition. Moreover, overmatch conditions in welded joints have detrimental effects on fatigue crack propagation rate. The fatigue life can be reduced by more than 70% for a condition of 50% overmatch when compared with the evenmatch condition.

scholarly journals Fatigue Crack Growth Rate of the Long Term Operated Puddle Iron from the Eiffel Bridge

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 53 ◽  
Author(s):  
Grzegorz Lesiuk ◽  
José A. F. O. Correia ◽  
Michał Smolnicki ◽  
Abílio M. P. De Jesus ◽  
Monika Duda ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Fatigue Crack Growth Rate ◽  
Crack Opening ◽  
Low Carbon ◽  
R Ratio

The paper summarises an experimental study on the fatigue crack propagation and cracks paths in ancient steel—19th-century puddle iron from the Eiffel bridge. The tests were performed with the load R-ratio equal to 0.05 and 0.5. All tests were performed under different notch inclinations (mode I + II). The fatigue crack growth rate in the tested material is significantly higher than its “modern” equivalent—low carbon mild steel. The crack closure phenomenon occurs in specimens during the process of crack growth. Understanding this aspect is crucial for the examination of a stress R-ratio influence on kinetic fatigue fracture diagram (KFFD) description. Both the experimental and numerical approach, using the HP VEE environment, has been applied to the crack closure as well as the crack opening forces’ estimation. These analyses are based on the deformation of the hysteresis loop. The algorithm that was implemented in the numerical environment is promising when it comes to describing the kinetics of fatigue crack growth (taking into consideration the crack closure effect) in old metallic materials.

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