Numerical analysis of the fatigue crack growth on gears

During designing it is important to be able to know as accurately as possible the entire service life. In this case the model of initiation and growth of short cracks as well as model of growth of long cracks are important. From the theory it is known that the defects, i.e., the cracks causing destruction or fracture of the basic function of the individual components, spent almost 80 - 90 percent of the entire service life in micro conditions, i.e., in conditions in which they cannot be detected by standard non-destructive methods. Therefore it is very important to have as precise computation models for determination of the service life. For this area we used Bilby, Cottrell and Swinden model which is based on the theory of continuously distributed dislocations. In the presented work the model is complemented with random generation of structure of material before cracks. Such a model is intended for "narrow" gears where it is possible to assume that the crack propagates uniformly along entire width.