Phase Transformation Theory Applied to Predict Fatigue Crack Propagation in Solid Materials

Mechanical deformation of a solid during fatigue cycling is broadly defined a phase transformation, because defects are produced that increase its internal energy. Change in the defect structure, crack initiation and growth are also examples Of phase transformations. Many of the concepts of phase transformation theory are applicable to fatigue crack nucleation and propagation. The physical meaning of fatigue crack propagation in solid materials is studied by using energy considerations. Phase transformation theory is applied to predict the fatigue crack propagation rate in metals and alloys. The fatigue crack propagation rates predicted is compared with experimental data for different steels and aluminum alloys to demonstrate that the prediction of the theory agrees reasonably well with experimental results. The theory is applicable to predict fatigue crack propagation in solids under cyclic stress with corresponding experimental data.