Abstract
In engineering applications, fractures occur mostly from surface or internal three-dimensional cracks due to defects already existing in the material. These generally propagate in all directions and often have irregular shapes, and are not limited only to metallurgical defects but also include those which are due to the fastening of parts, configuration design, as well as those that result from the need to provide lubrication of ships and offshore structures. Since these generate a stress concentration zone, fatigue crack initiation and propagation are strongly affected. However, these are inevitable in design. Therefore, a study on the characteristics of fatigue crack growth that occur when surface cracks initiated from initial defects propagate into stress concentration zones such as those in lubricating oil holes of connecting rods was conducted.
