Dynamics and Stability of Magnetically Actuated Pipes Conveying Fluid

This paper is concerned with the development of a theoretical model for predicting the dynamics and pull-in instability of magnetically actuated pipes conveying fluid. The equation of motion of the pipe is constructed in the presence of nonlinear magnetic forces. The lateral displacement of the pipe comprises two parts, namely, a static displacement and a perturbation displacement about the static. Based on the finite element method (FEM), the static deflection of the pipe is calculated numerically first. The computed static deflection is then used to solve the equation governing the perturbed displacement. Consequently, the pull-in and flow-induced instabilities can be determined for clamped-clamped or cantilevered boundary conditions. Results show that the flow speed can significantly affects the static deflection of the pipe and hence the pull-in magnetic force. The magnetic force, on the other hand, has a great impact on the dynamics of the pipe system.