Enhancing flutter and buckling capacity of column by piezoelectric layers

This paper illustrates the use of a pair of piezoelectric layers in increasing the flutter and buckling capacity of a column subjected to a follower force. The column is fixed at one end while the other one is free to rotate but constrained transversely by a spring. The mathematical formulation is presented and solved numerically. The effect of the spring stiffness on the capacity and type of instability of the column is first illustrated numerically for the case without any piezoelectric actuators. A transition value for the stiffness can be identified, below which the column fails by flutter and above which the column buckles. Next, an external voltage is applied on the piezoelectric layers bonded on the surfaces of the column, which induces locally a pair of tensile follower force. This has the effect of increasing the capacity of the column as the voltage increases while the transition stiffness remains virtually unchanged for a given size and location of piezoelectric actuators. It is also shown that the capacity of the column increases with longer layers for a fixed voltage. However, the location of the layers along the column determines the transition stiffness and hence has an effect on the type of failure for a fixed spring constant. Positioning towards the fixed end increases the flutter capacity whereas positioning away will result in an increase in buckling capacity. (C) 2002 Elsevier Science Ltd. All rights reserved.