NONLINEAR IMPACTING OSCILLATIONS OF PIPE CONVEYING PULSATING FLUID SUBJECTED TO DISTRIBUTED MOTION CONSTRAINTS

The nonlinear dynamics of a simply supported pipe conveying pulsating fluid is investigated by introducing distributed motion constraints along the pipe axis. The constraints are modeled by trilinear springs. The flowing fluid in the pipe is pulsatile, which is assumed to have a time-dependent harmonic component superposed on the steady fluid flow. Attention is concentrated on the potential performance of the pipe/impacting system with various pulsating frequencies. To investigate the short-wave buckling, the behaviors of the simply supported pipe with steady internal flow velocities are presented first. The partial differential equations (PDEs) are formulated and then transformed into a set of ordinary differential equations (ODEs) using the Galerkin's method. The nonlinear dynamical responses are presented in the form of bifurcation diagrams, time histories, phase portraits, Poincare maps and power spectrums. Some interesting and sometimes unexpected results have been observed under various system parameters.