NONLINEAR ACTIVE VIBRATION CONTROL OF A CANTILEVER PIPE CONVEYING FLUID

Active vibration suppression of a fluid conveying cantilever pipe with geometric non-linearity due to post-critical flow speed is examined. The non-linear characteristics of the system is described using the fi ctitious load approach and the dynamic responses can be obtained using successive co-ordinate transformations, which only require the soluti on of linear differential equations, without the need to deal with the complex non-linear strain-displacement relationships. An instantaneou s optimal closed loop control approach by minimizing an objective func tion at each time instant is developed using the Newmark method for so lution of the linear equations of motion. The effect of actuator locat ion on the performance of the control system is described. It is demon strated that the control design is also applicable for vibration suppr ession of the fluid conveying cantilever pipe subjected to random base excitations. (C) 1997 Academic Press Limited.