Fatigue crack growth in bending: Successful correlation of mean stress (stress ratio) effects using the change in net-section strain energy

2018 ◽  
Vol 41 (12) ◽  
pp. 2566-2576 ◽  
Author(s):  
K.S. Ravi Chandran
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Strain Energy ◽  
Stress Ratio ◽  
Mean Stress

The Effect of Stress Ratio on Fatigue Crack Growth in a Biaxial Stress Field

1977 ◽  
Vol 99 (1) ◽  
pp. 137-143 ◽  
Author(s):  
S. Y. Zamrik ◽  
M. A. Shabara
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Stress Field ◽  
Crack Growth ◽  
Stress Ratio ◽  
Biaxial Stress ◽  
Stress System ◽  
Mean Stress ◽  
Principal Stresses ◽  
Stress Ratios

The effect of stress ratio (mean stress) on fatigue crack growth in a biaxial stress field was investigated. The biaxiality was introduced by means of anticlastic bending of rhombic plates. A crack initiator in the form of an EDM slot was embedded in the top surface of plate specimen. The crack tip was subjected, as a result of specimen bending, to two principal stresses, one tensile and normal to the crack and the other parallel to it but in a compressive direction. Three mean stress ratios of R = Kmin/Kmax were applied, one in a zero to tension mode, the second in a completely reversed cycling where the stress ratio R = −1, and the third in an intermediate ratio of R = −0.5. All stress ratios were imposed in an existing biaxial stress field. Uniaxial concepts such as Walker’s approach were analyzed and applied to biaxial stress system. Experimental results have shown that fatigue crack growth is influenced by both variables: mean stress ratio and stress biaxiality ratio. Each variable was isolated by using the concept of effective stress intensity range ΔK. The crack growth and the fracture mode under each type of loading are discussed and analyzed.

Application of the R-Curve Concept to Fatigue Crack Growth

1978 ◽  
Vol 100 (4) ◽  
pp. 416-420 ◽  
Author(s):  
D. P. Wilhem ◽  
M. M. Ratwani
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Extension ◽  
Stress Ratio ◽  
Cyclic Stress ◽  
Crack Growth Resistance ◽  
Resistance Curve ◽  
Cyclic Stress Ratio ◽  
Wide Range

Crack growth resistance for both static (rising load) and for cyclic fatigue crack growth has been shown to be a continuous function over a range of 0.1 μm to 10 cm in crack extension for 2024-T3 aluminum. Crack growth resistance to each fatigue cycle of crack extension is shown to approach the materials ordinary undirectional static crack resistance value when the cyclic stress ratio is zero. The fatigue crack extension is averaged over many cycles and is correlated with the maximum value of the crack tip stress intensity, Kmax. A linear plot of crack growth resistance for fatigue and static loading data shows similar effects of thickness, stress ratio, and other parameters. The effect of cyclic stress ratio on crack growth resistance for 2219 aluminum indicates the magnitude of differences in resistance when plotted to a linear scale. Prediction of many of these trends is possible using one of several available crack growth data correlating techniques. It appears that a unique resistance curve, dependent on material, crack orientation, thickness, and stress/physical environment, can be developed for crack extensions as small as 0.076 μm (3 μ inches). This wide range, crack growth resistance curve is seen of immense potential for use in both fatigue and fracture studies.

Effect of Hardness and Tensile Mean Stress on Fatigue Crack Growth in Beryllium Copper

1969 ◽  
Vol 11 (3) ◽  
pp. 343-349 ◽  
Author(s):  
L. P. Pook
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Residual Stresses ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Mean Stress ◽  
Growth Data ◽  
Beryllium Copper

Some fatigue crack growth data have been obtained for age-hardened beryllium copper. The fatigue crack growth rate was found to be very dependent on the hardness and tensile mean stress. This dependence is believed to be associated with the intense residual stresses surrounding Preston-Guinier zones.

scholarly journals Effects of Cycle Frequency, Mean Stress, Temperature and Cathodic Protection on Fatigue Crack Growth in 3% Salt Water

1976 ◽  
Vol 1976 (140) ◽  
pp. 241-247
Author(s):  
Kin-ichi Nagai ◽  
Mitsumasa Iwata ◽  
Hiroshi Yajima ◽  
Yutaka Yamamoto ◽  
Yukio Fujimoto
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Cathodic Protection ◽  
Salt Water ◽  
Mean Stress ◽  
Cycle Frequency
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