Study of Variability of the Crack Growth Rate by Applying a Crack Growth Model to Sequences of Extrema Modeled by Markov Matrices

The stage of crack propagation in aircraft structures under fatigue is of great interest. The problem of variation in the duration of fatigue crack growth is considered. Under irregular loading, durability can vary significantly. For this study, loading processes are modeled using the Markov address matrix method and several replicas of the initial process are obtained. The fatigue life of each replica is calculated using the Willenborg crack growth retardation model. A model for random processes, the TWIST sequence, which is widely used in aviation to investigate the likely scatter of durability due to the uncertainty of load information in a numerical experiment, is used as the basis for the simulation.