Fatigue cycle number

It is worth noting the difference in the fatigue resistance characteristics of 1 and 3.[131 Compound la has methyl groups at the 4- and 4 -positions of the thiophene rings, while compound 3a has no methyl groups at these positions. Figure 2 shows the cycle number dependence of absorbances of the bleached samples. 

Figure 17 Sensitometry as a function of cycle number. The first cycle characteristics, Vdark, Vmidy and Verase correspond to the voltages obtained with no exposure (dark), exposure to one-half of the initial potential (mid), and those obtained following the erase exposure. The potentials obtained with the same exposures after 104 cycles are also shown. In this example, the photoreceptor fatigued with decreasing Vdark and increasing Verase These characteristics are often described as cycle-down and cycle-up.

Retarded fatigue crack growth (RCG) was first observed by Elinck et al. in PVC, and was called discontinuous initially. They noted that the crack propagated step-wise and that a great number of fatigue cycles was needed for the formation of successive markings on the fracture surface. 

Figure 16.5. Crack length vs. the number of fatigue cycles for PC/ABS blends filled with 8 wt% talc and unfilled. [Adapted, by permission, Irom Seibel S R, Moet A, Bank D H. Nichols K, Antec 93. Conference Proceedings, New Orleans, La., 9th-13th May 1993, Vol. I, 902-5.]...

The number of fatigue cycles associated with pit growth (A pit) and for fatigue crack growth (A feg), and the overall fatigue life Np) in a smooth specimen are as follows ... 

Fatigue Life - Number of loading-unloading cycles of a specified type of material that can endure before failing in a fatigue test. 

Fig. 3. Critical current as a function of the number of fatigue cycles between zero stress and the maximum stress indicated on each curve, et refers to the total strain of the maximum stress, Ac refers to the peak-to-peak strain amplitude as defined in Fig. 4. Critical current was measured by stopping the cyclic loading at maximum.

Fig. 6. Stress-strain curves for the multifilamentary NbTi Cu specimen as a function of the number of fatigue cycles. Each curve has been horizontally displaced to show more clearly the change in enclosed area with fatigue.

In the irreversible region, however, a limited amount of fatigue damage did occur. For example, on cycling the specimen 30,000 times between zero stress and point 4 in Fig. 10 (about 0.9% strain), Ic degraded about 25%, as shown by point 4 in Fig. 10. Most of the h degradation occurred in the first 10 cycles, however. This is shown in Fig. 11, where h is plotted as a function of the number of fatigue cycles, N, at various strain levels in both the reversible (upper curve) and irreversible... 

Fig. 11. Normalized critical current as a function of the number of fatigue cycles, showing the difference in initial fatigue behavior between the upper curve, taken in the reversible region, and the lower two curves, taken in the irreversible region.

Ic = critical current Icm - maximum critical current Ico = critical current at zero external stress Jc = critical current density N = number of fatigue cycles R — resistance... 

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