Crack Growth Models

The analysis of fatigue failure of structural elements using the fracture mechanics approach requires the knowledge of how the crack size a grows with alternating fatigue loads (see FKM-Guideline (2003), FKM-Guideline (2004), BS7910 (2004) and SINTAP (1999)). The problem is usually simplified by considering that the largest crack in the structural element is the dominant crack leading to failure, and assuming that the crack growth speed ratio da/dN is controlled by the stress intensity factor range ΔK and the stress ratio R^*=σ _m /σ _M , where σ _m and σ _M are the minimum and maximum stresses, respectively, which is known as the crack growth function.