Analysis of the dynamic stability of collar-stiffened pipes conveying fluid

The dynamic stability of a collar-stiffened pipe conveying fluid was examined by using the Euler–Bernoulli beam theory. The pipe considered consists of identical substructures, or cells, connected in an identical fashion. Each substructure, or cell, comprises a uniform pipe segment and a collar. A finite element model was developed to predict the dynamic stability of the stiffened pipe under the action of the flowing fluid. Stability maps were obtained for clamped-free collar-stiffened pipes of various design parameters. The design parameters included the arrangement and the geometry of the identical cells. The stability maps demonstrated that the collar-stiffened pipe exhibits unique stability characteristics when compared to a uniform pipe. It was found that the stable region in the stability map enlarges for the collar-stiffened pipe when compared to a uniform pipe. To give clearer insight into the pipe dynamic behavior, the dynamic response and eigenvalue branches were presented for a number of collar-stiffened pipes.