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.

Plane Strain Crack Growth Models for Fatigue Crack Growth Life Predictions

1996 ◽  
Vol 118 (1) ◽  
pp. 78-85 ◽  
Author(s):  
J. M. Bloom ◽  
S. R. Daniewicz ◽  
J. L Hechmer
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Crack Opening ◽  
Constraint Factor ◽  
R Ratio ◽  
Point Bend

Experimental data and analytical models have shown that a growing fatigue crack produces a plastic wake. This, in turn, leads to residual compressive stresses acting over the crack faces during the unloading portion of the fatigue cycle. This crack closure effect results in an applied stress intensity factor during unloading which is greater than that associated with the Kmin, thus producing a crack-driving force which is less than ΔK = Kmax − Kmin. Life predictions which do not account for this crack closure effect give inaccurate life estimates, especially for fully reversed loadings. This paper discusses the development of a crack closure expression for the 4- point bend specimen using numerical results obtained from a modified strip-yield model. Data from tests of eight 4-point bend specimens were used to estimate the specimen constraint factor (stress triaxiality effect). The constraint factor was then used in the estimation of the crack opening stresses for each of the bend tests. The numerically estimated crack opening stresses were used to develop an effective stress intensity factor range, ΔKeff The resulting crack growth rate data when plotted versus ΔKeff resulted in a material fatigue crack growth rate property curve independent of test specimen type, stress level, and R-ratio. Fatigue crack growth rate data from center-cracked panels using Newman's crack closure model, from compact specimens using Eason 's R-ratio expression, and from bend specimens using the model discussed in this paper are all shown to fall along the same straight line (on log-log paper) when plotted versus ΔKeff, even though crack closure differs for each specimen type.

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.

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 Rates of HPS 485W in China

2010 ◽  
Vol 452-453 ◽  
pp. 157-160
Author(s):  
Chun Sheng Wang ◽  
Lan Duan ◽  
Jing Yu Hu
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
High Fracture Toughness ◽  
Stress Intensity Factor Range ◽  
Low Carbon ◽  
High Fracture

This paper provides an introduction of existing fatigue and fracture behavior studies about high performance steel (HPS). This paper is emphasis on the crack propagation studies of HPS 485W, which is a new kind of structural weathered steel produced by Wuyang Steel Company using quenching and tempering (Q&T) in China. HPS has more advantages than traditional steel, such as high fracture toughness and cracking tolerance, high strength, low preheating weld or no preheating, recycle using and so on, so it can be used in sustainable bridge and building structures with low carbon releasing. To ensure the using safety and extend applying area of the new green civil material, the key material properties of HPS should be studied, such as fatigue crack growth rate. Fatigue crack growth rate characterizes the material resistance to stable crack extension under cyclic loading. A set of 5 compact specimens were made from 8mm and 14mm thick HPS 485W separately. Fatigue crack growth rate function of crack-tip stress-intensity factor range, da/dN versus ΔK, is proposed based on the test results, which shows HPS has high cracking tolerance ability.

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