DYNAMIC ANALYSIS OF A SIMPLY SUPPORTED FLUID-CONVEYING PIPE WITH A MASS ATTACHED IN THE MIDDLE OF THE SPAN

Resumo

In this paper, the planar dynamics of a simply supported fluid-conveying pipe with a mass attached in the middle of the span are analyzed. Primarily, as external forces, a pulse load applied at the middle point, and the self-weight of the pipe-fluid system, were considered. For such loads, the dynamic behavior was analyzed for different flow velocities. Additionally, to the current external applied forces, a gravitational force has been considered, because of the attached mass at the middle span. The pipe was considered an Euler-Bernoulli beam having a non-negligible flexural rigidity. Only transversal and angular displacements related to the undeformed pipe axis were considered. We assume an incompressible fluid and an elastic pipe material. The equation of motion for the model is obtained using Hamilton's variational principle. The direct integration of the dynamic equations was solved by the Galerkin's method. Numerical analysis and simulations were performed using a code developed in Matlab. This paper demonstrated that, in the presence of the attached mass, for different flow velocities, the system frequencies decrease with time, for increasing flow velocities, approaching zero at the theoretical critical velocity.