Simulation of microcrack growth under multiaxial random loading and comparison with experimental results

In this paper a model designed to simulate the growth of microcracks under the influence of cyclic loading is presented. Considering fatigue crack growth microstructural barriers as well as the state of stress play an essential role. The crack growth is initially dominated by shear stresses leading to microstructurally short cracks (stage I). As the tip of the microcrack approaches a grain boundary the crack growth rate decreases. The transition from stage I to stage II crack growth is also considered in the model as the crack reaches a specific length and continues to grow under the influence of maximum normal stresses (physically short cracks). The comparison of the simulation results to experimental results of variable amplitude loading for bending, torsion, multiaxial proportional loading and multiaxial non-correlated loading applied to notched specimens of 42CrMo4V reveals a close match with the experimental results.