Subcritical Crack Growth

So far two types of crack extension have been considered: stable crack extension starting at K₁ =K₁₀ and unstable crack extension, if K₁=K_1inst is reached (or at K₁ =K_1c for a material with a flat crack growth resistance curve). A third type of crack extension is called subcritical crack extension. This is a time-dependent phenomenon, where a crack is growing at constant load below K₁ =K_1inst. In this section the subcritical crack extension below the high temperature regime is considered. The creep crack growth is described in Sect. 12.2. The subcritical crack extension under cyclic loading is dealt with in Chap. 6.