Stability Control of Active Compressed Rods with Shape Memory Polymers

Abstract

In structural systems, applied compressive force fields cause second-order effects that may not only influence the buckling behavior, but also enhance the internal stress and the deformation field in the structure. Specifically, slender and thin-walled structural elements subjected to compressive force fields may experience buckling instability, which may affect their service life. In the case of imperfection-sensitive systems, loading and geometric imperfections may drastically affect the buckling response and reduce the buckling resistance. This behavior may be positively influenced by a structural adaptation to bending effects. In this connection, an attempt is made to use the potentials of the adaptive systems to influence the second-order as well as the buckling response of the slender compression elements by means of the actuator components. To this end, the stability control problem of adaptive slender rods with embedded Shape Memory Polymer (SMP) actuators is theoretically treated. The main goal of this investigation was to explore the possibility of minimizing the end deflection of a cantilever rod under eccentrically applied force via actuation of an SMP fiber. First, the stability theory of spatial rods is outlined, and the non-linear governing equations of straight rods are derived. The specific case treated is the problem of a cantilever rod with a single eccentric SMP fiber under eccentrically applied end compressive force. Numerical calculations were carried out with the help of the Runge-Kutta method. It is shown that the response of the rod can be effectively controlled by the appropriate action of the SMP actuator. Specifically, the goal of minimizing the end deflection of the eccentrically loaded cantilever rod through the action of the SMP actuator is achieved. In carrying out the computations, the second-order effects arising from the action of SMP fiber as well as the axial force were taken into consideration. Moreover, the follower action of the SMP force was considered.

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