scholarly journals Analyses of Fatigue Crack Growth and Closure Near Threshold Conditions for Large-Crack Behavior

2008 ◽  
pp. 227-227-25 ◽  
Author(s):  
JC Newman
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Large Crack ◽  
Crack Behavior ◽  
Threshold Conditions ◽  
Near Threshold

Near-Threshold Fatigue Crack Growth at 63Sn37Pb Solder Joints

2002 ◽  
Vol 124 (4) ◽  
pp. 385-390
Author(s):  
Ki-Ju Kang ◽  
Seon-Ho Choi ◽  
Tae-Sung Bae
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Tests ◽  
Lap Joint ◽  
Growth Data ◽  
Micro Structure ◽  
Crack Behavior ◽  
Temperature Aging ◽  
Near Threshold

Fatigue tests were performed using single lap-joint specimens to obtain near-threshold fatigue crack growth data of solder joint under mode-II load. Attention was focused on the effect of high temperature aging and microstructures separately from the intermetallics. As a result, it was shown that the long cast time yielded the intermetallics and microstructures of the solder invariable regardless of aging condition. The granular micro-structure of the air-cooled specimens was shown to be inferior to the laminated micro-structure of the furnace-cooled specimens. Also, transition of fatigue crack behavior with ΔJ and the procedure of fatigue crack propagation from the pre-crack tip were discussed.

Effect of Absorbed Hydrogen on the Near Threshold Fatigue Crack Growth Behavior of Short Crack

2007 ◽  
Vol 567-568 ◽  
pp. 409-412 ◽  
Author(s):  
Keiko Shishime ◽  
Masanobu Kubota ◽  
Yoshiyuki Kondo
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Characteristic ◽  
Propagation Characteristic ◽  
Carbon Steels ◽  
Crack Growth Behavior ◽  
Integrity Assessment ◽  
Crack Behavior ◽  
Near Threshold

Hydrogen is considered to be a possible energy source in the coming future. However, it has been recognized that hydrogen has a detrimental effect on the fatigue strength of metal. The fatigue crack growth characteristic is an important property for the integrity assessment of hydrogen utilization machine. In this report, the effect of hydrogen on the fatigue crack propagation characteristic was studied using low alloy steel, carbon steels and A286 alloy. Especially in this study, very short pre-cracked specimen as small as 0.03 mm deep was used and the near threshold fatigue crack behavior was studied. As a result, materials whose Vickers hardness was higher than 300 were found to be susceptible to absorbed hydrogen.

Crack Closure Behavior under High-Load Ratio for AISI 4340 Steel

2011 ◽  
Vol 462-463 ◽  
pp. 54-58
Author(s):  
M. Abdul Razzaq ◽  
Ahmad Kamal Ariffin ◽  
Shahrum Abdullah ◽  
Z. Sajuri
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Closure ◽  
Fatigue Crack Growth Rate ◽  
Threshold Conditions ◽  
Near Threshold ◽  
Aisi 4340

In this paper, fatigue crack growth rate (FCGR) analyses were conducted on compact specimens of an AISI 4340 alloy to study the behavior over a range in load ratios (0.1 ≤ R ≤ 0.95) and constant maximum stress intensity factor (Kmax) condition. Previous study had indicated that high R > 0.7 and constant Kmax test conditions near threshold conditions were suspected to be free of crack-closure and that any differences were caused by Kmax effects, from threshold to near fracture conditions. Cracks in high-cycle fatigue (HCF) components spend a large portion of their fatigue life near threshold conditions. In order to characterize the evolution of damage and crack propagation during these conditions, fatigue crack growth rate (FCGR) data at threshold and near-threshold conditions are essential in predicting service life and in determining the proper inspection intervals. Fatigue crack growth model, namely the Forman model were examined, this model implicit the effect of R ratio and ease of curve fitting to measured data. The Forman model may be suggested for use in critical applications in studying fatigue crack growth for different load ratios.

Evaluation of Fatigue Crack Growth Curves in Existing Codes and a Proposed Modification Based on Experimental Data of Cr-Ni-Mo-V Steel Welded Joints

2016 ◽  
Author(s):  
Yan-Nan Du ◽  
Ming-Liang Zhu ◽  
Fu-Zhen Xuan ◽  
Shan-Tung Tu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Welded Joints ◽  
Growth Curves ◽  
Crack Growth Behavior ◽  
Fatigue Assessment ◽  
Crack Growth Model ◽  
Threshold Regime ◽  
Near Threshold

A comparison of currently available codes for assessment of fatigue crack growth, including ASME (America Society of Mechanical Engineers) SEC. XI, FKM (Forchungskuratorium Maschinenbau) guideline, WES (Japan Welding Engineering Society) 2805, BS7910 and JSME (The Japan Society of Mechanical Engineers), was carried out by paying attention to the suitability of application and the easiness to obtain the parameters, based on fatigue crack growth data of Cr-Ni-Mo-V steel welded joints. Results showed that fatigue crack growth curves provided by the FKM or WES were good choice when few inputs were at hand while the curves in the BS7910, JSME and ASME were recommended for precise estimation. It was indicated that the assessment of welded joints solely by fatigue crack growth behavior at base metal part and the assessment of fatigue crack growth for the aged condition by as-received one both resulted in non-conservativeness, albeit dependent on the range of stress ratios, R. A new bilinear form of fatigue crack growth model independent of R was developed based on transition point occurred in the near-threshold regime. This constituted the bilinear approach to fatigue assessment, and thus contributed to the optimization of fatigue assessment in the near-threshold regime.

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