Numerical analysis of fatigue crack growth using a plastically dissipated energy factor based model

Author(s):  
Jie Wang ◽  
Wei Jiang

The investigation of fatigue crack growth (FCG) behavior may contribute to the assessment of damage tolerance of components. To study the FCG behavior considering the elastic–plastic behavior at the crack tip, a numerical simulation scheme based on compact tension (CT) specimen is developed. Also, an effective plastically dissipated energy (PDE) factor composed of maximum PDE ([Formula: see text]) and PDE range ([Formula: see text]) is proposed to establish the expression for evaluating the FCG rate. The simulation results show good agreement with the results of test under same load conditions. Also, the mesh sensitivity analysis and the comparison with test results confirm the validation of proposed model. Based on the proposed numerical simulation scheme, the FCG behavior is studied by analyzing the influence of plastic wake, mean load, load range, overload, underload, load sequence, and cyclic compression load on FCG from the perspective of crack driving force, FCG rate, and crack opening displacement (COD). It is found from the analysis results that the developed numerical simulation scheme can consider the load history effect and crack closure effect. The mechanisms of these factors on the influence of FCG rate are analyzed in detail.

2000 ◽  
Author(s):  
Yoshihisa Tanaka ◽  
Yu-Fu Liu ◽  
Chitoshi Masuda

Abstract The fatigue crack growth behavior in SiC (SCS-6) fiber reinforced Ti-15-3 matrix alloy composite subjected to a constant tension-tension loading mode was studied using single edge specimen in 2 × 10−3 Pa vacuum at 293 and 823K, with a frequency of 2 Hz, and a stress ratio of R = 0.1. Direct measurement of the fatigue crack length, and the crack opening displacement along the crack wake during the test were carried out by scanning electron microscope (SEM). The increase in the test temperature was found to lead to a decrease in the fatigue crack growth rate. The degradation of bridging fibers in the crack wake was severe for T = 293K, and this behavior was dependent of the test temperature. Fine particle-like debris was found on the fracture surface in the region of crack propagation in specimens tested at T = 823K. This is thought to be caused by the interface wear behavior. The crack opening displacement along the crack wake tested at T = 823K decreased with increasing crack length, and this tendency is dependent on the applied stress range. The associated increase in the crack tip shielding is explained on the basis of the crack closure due to the matrix relaxation by fatigue creep and the interface wear behavior.


1972 ◽  
Vol 8 (2) ◽  
pp. 209-219 ◽  
Author(s):  
R. J. Donahue ◽  
H. McI Clark ◽  
P. Atanmo ◽  
R. Kumble ◽  
A. J. McEvily

Author(s):  
R.J. Donahue ◽  
H.McI. Clark ◽  
P. Atanmo ◽  
R. Kumble ◽  
A.J. McEvily

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