Limits of Stress Reduction in a Plate with a Hole Using Piezoelectric Actuators

Recently there has been much interest in adaptive structures that can respond to a varying environment by changing their properties. Shape memory alloys and piezoelectric materials can be used as induced strain actuators to reduce stresses in regions of stress concentration. In a previous work, we have shown that stress concentration in a plate with a hole can be reduced substantially by applied induced strain. However, limited free induced strain (1000 JAE) and low tensile strength limit the effectiveness of piezoceramics for active stress alleviation. Also, bonded actuators increase the weight of the structure and may have shear lag effects. The present work determines the effects of such limitations on stress reduction for two load cases: a fatigue load case and an extreme load case. Piezoelectric actuators were found to be ineffective in reducing stress concentration factor for the extreme load case. For the fatigue load case, effectiveness depends on the cost and weight associated with supplying actuation energy.