Accounting for straight parts effects on elbow's flexibilities in a beam type finite element program

An extension of Von Karman's theory is applied to the calculations of the flexibility factor of a pipe bend terminated by a straight part or a flange. This analysis is restricted to the linear elastic deformation behaviour under in plane bending. Analytical solutions are given for the propagation of ovalization in the elbow and in the straight part. Considering the response of the piping structures, we note that the ovalization of the piping systems are reduced significantly when the straight parts or flanges effects are included. The results are presented in terms of global as well local flexibility factors. They have been compared to numerical results obtained by shell type finite element method. A complete piping system is analyzed, for economical reasons, with a beam type approach. Also, we show how it is possible to take into account on elbow's flexibilities the straight parts effects by means of flexibilities factors introduced in a beam type element. We have implemented this method in the computer program TEDEL. In some specific geometrical features, we compare solutions using shell type elements and our formulation