Probabilistic description of fatigue crack growth in polycrystalline solids

Abstract A stochastic model describing the crack evolution and scatter associated with the crack propagation process has been built on the basis of the discontinuous Markovian process. The evolution and scatter are identified in terms of constant probability curves whose equation is derived as In P r (i) = B(e KI 0 − e Ki ) , i ≥ I 0 , where i is the number of cycles, B and K are crack-length-dependent variables, P r (i) is the probabiliity of the crack being at position r along the fracture surface after i cycles elapse and I 0 is the minimum number of cycles required for the crack to advance from one position on the fracture surface to the next. The validity of the model is established by comparing the crack growth curves generated for Al 2024-T3 at a specific loading condition with those experimentally obtained.