Optimal Relaxation of Stress Concentrations in Adaptive Structures by Using Piezoelectric Actuators

Smart structures using induced strain actuators, for example, piezoelectric actuators or shape-memory alloys, may be expected to achieve active damage control. In particular, piezoelectric actuators have the capability to induce various amounts of strain upon being activated, therefore, it is possible to reduce the stress concentrations under varying external load conditions by distributing them in high stress regions in advance. In this paper, an adaptive structure model is proposed for reduction of stress concentrations by using piezoelectric actuators. The model is concerned with a simple actuator/substructure system in which the substructure is an infinite isotropic plate with a circular hole, and actuators are bonded to the plate surfaces around the hole. In order to examine the performance of the adaptive structure, optimally applied voltage to each piezoelectric actuator is calculated to minimize the maximum circumferential stress at the hole boundary in the cases of some external stress conditions.