Crack-growth curve

Fig. 8.59 Features of a corrosion fatigue crack growth curve...

Figure 7.9. Constant load-amplitude fatigue crack growth curves for a mill-annealed T1-6A1-4V alloy tested in vacuum at room temperature [4],...

Here, B is the amount of crack growth apparently occurring at the point where the fatigue crack growth curve is extrapolated to intersect with the asymptote associated with the fracture strength, Gc- A typical value is roughly 0.01 mm/cyc. A simple empirical form for a R) is... 

Figure 7.72 Different effects of enviromnent on the crack growth curve.

This means that an increasing stress ratio R moves the crack growth curve to the left in the log da/dN-log AK diagram. 

Figure 7.73 Crack growth curves for a St 52-3 steel in air, in seawater with fiee corrosion, and with cathodic protection at two different potentials, f = 0.17-1 Hz, t=5-12 C,R = 0.5 [7.59].

As an example, the graphic representation in Figure 5.13. shows crack growth curves of natural rubber compounds reinforced with layered silicate and silica. It can be seen that the crack propagation behaviour is different in dependence on the filler type and on the content of the layered silicate, too. The slope of the crack propagation curve is decreased by adding 60 phr in comparison to 15 phr layered silicate and to 60 phr silica. This means, the crack growth speed is reduced. 

Fig. 3.1-178 Crack growth curve near threshold stress intensity of a center surface cracked specimen machined from a recrystallized Mo5Re rod, tested at a stress ratio of R = —l. test temperature = 50 °C, and 20 kHz cychc frequency open symboh test under increasing load, solid symbols tests under decreasing load [1.126]...

Most metal-environment systems do not yield experimental crack growth curves with such well pronounced characteristics. The identification of the different mechanisms contributing to crack growth is then more difficult. One may expect that similar mechanisms as those responsible for crack growth under static conditions... 

Figure 26. Fatigue crack growth curve for DCB specimens.

This shape of the crack growth curve Aa/dt is very similar to the crack-growth rate Aa/AN in cyclic loading of metals, to be discussed in section 10.6.1. 

Fig. 10.16. Crack-growth curve, plotting da/d7V versus the cyclic stress intensity factor AK in a double-logarithmic plot. There are three characteristic regions as shown for the curve with the R ratio Ri...

Fig. 10.17. Crack-growth curves of several materials An aluminium alloy (AlZn 6 CuMgZr), a steel (20MnMoNi4-5), a nickel-base superalloy (Waspaloy), a titanium alloy (TiA16V4), silicon carbide, and a psz ceramic [6,38,53,57,87]...

In region III, the crack velocity is independent of the partial pressure of water. The shape of the crack-growth curve in region III has been explained by Wiederhorn et al. [12] in terms of electrostatic interactions between the environment and charges that develop at the crack tip during fracture. 

Experimental fatigue crack growth curve for a CFRP-epoxy double cantilever beam (Data from Ashcroft and Shaw 2002)... 

The present paper describes the main elements of a novel concept for lifetime and safety assessment of PE pressure pipes for arbitrary installation conditions based on modem methods of fracture mechanics. At the core of the proposed concept is the accelerated generation of so-called synthetic crack growth curves and corresponding material laws for crack growth initiation and slow crack growth for service-near temperature conditions without the use of stress cracking liquids. 

The relationship between crack growth curves of this type and results from the internal pressirre-creep stress rapture testing of pipes is also illustrated schematically in Figirre 2. The relationship for a quantitative lifetime model for the internal pressure-creep stress behavior according to... 

For the generation of crack growth curves for arbitrary forms of loading, especially for static long-term loading, the procedure outlined schematically in Figure 5 can be applied. The five key steps in this procedure are ... 

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