Maximum stress intensity factor

Rmax Maximum stress intensity factor (MPa m1/2) (cyclic tests)... 

A comparison of the crack velocities measured under static and cyclic loads is illustrated in Fig. 7.2. For this purpose, the crack velocity under cyclic loads, da/dt = da/dN x vc, plotted against the maximum stress intensity factor of the fatigue cycle, Kmax = AA7(1 — R), from the results shown in Fig. 7.1. The static crack velocity da/dt is also plotted against the stress intensity factor Kj corresponding to the applied load. In the intermediate range of crack growth, the static crack velocity generally follows the power-law relationship... 

Fig. 7.2 Cyclic crack growth velocity, da/dt = (da/dN) x vc, plotted as a function of maximum stress intensity factor, K, and static crack growth velocity, da/dt, plotted as a function of applied stress intensity factor, K, in AD 90 alumina in 1050°C air. After Ref. 34. Experimental conditions are the same as those in Fig. 7.1. Also shown are da/dt values predicted for cyclic loads on the basis of static fracture data using Eqn.

Fig. 8.16 Variation of static and cyclic fatigue crack velocity, daldt, with the applied (maximum) stress intensity factor, KIy for fatigue tests on A CVSiCw composites conducted at 1400°C. The inset shows a schematic of the change in crack velocity for a change from static- cyclic-> static loading at fixed Kt.51...

The figure illustrates type A true CF growth pattern in which the synergistic interaction between cyclic plastic deformation and environment produces cycle- and time-dependent crack growth rates. Tme CF influences cychc fracture, even when the maximum stress intensity factor in fatigue is less than A iscc-... 

Since valid Kic values could not be determined, the maximum load at failure was used to calculate the maximum stress intensity factor (ATmax) values. While ATmax is not a recognized measure of toughness, the values shown in Table VII support indications from the notch tensile and tear tests that the toughness of the 5083-0... 

Fig. 7.53 Maximum stress intensity factor (Kniax) and crack resistance (IQ) versus crack length I growth due to overload, II growth due to fatigue. III growth due to overload and fatigue [18]. With kind permission of John Wiley and sons...

Figure 12.43 Relationship between the stress intensity range h.K, corresponding to an arbitary value of Ac/AN 7.6 X 10 mcycle , and the maximum stress intensity factor range AZmax observed at failure for a group of polymers. The polymers are (1) cross-linked polystyrene, (2) PMMA, (3) PVC, (4) LDPE, (5) polystyrene, (6) polysulphone, (7) high-impact polystyrene, (8) ABS resin, (9) chlorinated polyether, (10) poly(phenylene oxide), (11) nylon 6, (12) polycarbonate, (13) nylon 6 6, (14) poly(vinylidene fluoride) (Reproduced with permission from Manson and Hertzberg, CRC Crit. Rev. Macromol. Sci., 1, 433 (1973))...

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