Stress intensity factors and fatigue growth of a surface crack in a drill pipe during rotary drilling operation

Drill pipe in a curved section of the drilled well is considered as a rotating hollow cylinder subjected to bending and tension loads. So in this paper, the stress intensity factors and the fatigue growth of a circumferential semi-elliptical surface crack in a hollow cylinder subjected to rotary bending and tension are studied. A stress intensity factor database for three loading cases is build for numerous configurations using 3D Finite Element Models. The crack propagation model employs the Walker fatigue growth rate law. Using this model, we can study the evolution of parameters characterizing the process of crack propagation.

► We study a hollow cylinder subjected to a combination of rotary bending and tension.
► A stress intensity factor database is built for circumferential semi-elliptical cracks.
► Walker law is used for computing crack propagation.
► The results show a very important role of the tension on the fatigue crack growth.
► The crack propagation life of drill pipes is calculated using this developed model.