scholarly journals Application of thermoelastic stress analysis for the experimental evaluation of the effective stress intensity factor

2013 ◽  
Vol 7 (25) ◽  
pp. 109-116 ◽  
Author(s):  
Francisco A. Díaz ◽  
Eann A. Patterson ◽  
John R. Yates
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Stress Analysis ◽  
Effective Stress ◽  
Experimental Evaluation ◽  
Thermoelastic Stress ◽  
Thermoelastic Stress Analysis ◽  
Effective Stress Intensity Factor

Effective Stress Intensity Factor in Mode III Crack Growth in Round Shafts

2003 ◽  
Author(s):  
A. Vaziri ◽  
H. Nayeb-Hashemi
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Fracture Surface ◽  
Crack Growth ◽  
Effective Stress ◽  
Mode Iii ◽  
Mode Iii Crack ◽  
Fracture Surfaces ◽  
Effective Stress Intensity Factor

Turbine-generator shafts are often subjected to a complex transient torsional loading. Such transient torques may initiate and propagate a circumferential crack in the shafts. Mode III crack growth in turbo-generator shafts often results in a fracture surface morphology resembling a factory roof. The interactions of the mutual fracture surfaces result in a pressure, and a frictional stress field between fracture surfaces when the shaft is subjected to torsion. This interaction reduces the effective Mode III stress intensity factor. The effective stress intensity factor in circumferentially cracked round shafts is evaluated for a wide range of applied torsional loadings by considering a pressure distribution in the mating fracture surfaces. The pressure between fracture surfaces results from climbing the rought surfaces respect to each other. The pressure profile not only depends on the fracture surface roughness (height and width (wavelength) of the peak and valleys), but also depends on the magnitude of the applied Mode III stress intensity factor. The results show that the asperity interactions significantly reduce the effective Mode III stress intensity factor. However, the crack surfaces interaction diminishes beyond a critical applied Mode III stress intensity factor. The critical stress intensity factor depends on the asperities height and wavelength. The results of these analyses are used to find the effective stress intensity factor in various Mode III fatigue crack growth experiments. The results show that Mode III crack growth rate is related to the effective stress intensity factor in a form of the Paris law.

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