OS0508 Measurement of Effective Stress Intensity Factor Range of Mode II Fatigue Crack Propagation

2011 ◽  
Vol 2011 (0) ◽  
pp. _OS0508-1_-_OS0508-3_
Author(s):  
Minjian LIU ◽  
Shigeru HAMADA
1973 ◽  
Vol 15 (4) ◽  
pp. 271-273 ◽  
Author(s):  
K. Jerram ◽  
E. K. Priddle

A new technique is described for determining the critical stress intensity factor required for fatigue crack propagation to occur. It enables data to be obtained more rapidly and with fewer testpieces than existing techniques. Initial results obtained for En 3A mild steel are in excellent agreement with published data.


Author(s):  
Motoki Nakane ◽  
Satoshi Kanno ◽  
Shota Hashimoto ◽  
Takayuki Watanabe ◽  
Yukio Takahashi

This study discusses methods for evaluating fatigue crack propagation under torsional loading for pipes. To achieve this objective, fatigue crack propagation tests were carried out on both stainless steel and carbon steel used in piping systems of nuclear power plants. Two different kinds of pipes were tested in this study. These pipes had the same shape but the diameter and thickness of the larger pipe were twice those of the smaller pipe. The nominal shear stress amplitudes applied to the specimen were set between 50 and 100 MPa depending on the dimension of the specimen and desired crack growth rates. All fatigue tests were conducted under pure torsional loading with stress ratio R = −1 and at room temperature. The geometrical correction factors for the specimen were derived from elastic J-integral calculated by the FEM. The fatigue crack propagation tests results show that the crack growth rates estimated by the elastic stress intensity factor with the geometrical correction factor were much faster than curves prescribed in The Japan Society of Mechanical Engineers (JSME) codes. These results suggest that elastic plastic fracture parameters should be considered into the stress intensity factor because yield stresses for torsional loading would be smaller than those of uniaxial loading. The plastic zone correction method and modified reference stress method were examined as alternative methods. The crack growth rates estimated by the proposed methods almost totally correspond to the JSME curves. The two proposed methods were found to be quite effective at correctly evaluating the crack growth rates under torsional loading.


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