Superconductor Conduits: Fatigue Crack Growth Rate and Near-Threshold Behavior of Three Alloys

Materials ◽  
1992 ◽  
pp. 167-174 ◽  
Author(s):  
A. Bussiba ◽  
R. L. Tobler ◽  
J. R. Berger
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Threshold Behavior ◽  
Near Threshold

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.

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