Control of stress and damage in structures by piezoelectric actuation: 1D theory and monofrequent experimental validation

Abstract

Summary This contribution presents novel results on feed‐forward control of stress in piezoelectric structures by means of piezoelectric actuation. For that sake, we focus on a one‐dimensional benchmark problem, a piezoelectric transducer that is excited by a piezoelectric stack actuator. We investigate the following problem: Is it possible to actuate the piezoelectric transducer in such a manner that the dominant axial stress component is nullified. In order to find a theoretical solution for this question, we discretize our system as a two‐degree‐of‐freedom (2DOF) model. The equations of motion are transformed into the differential equations for the inner forces by taking advantage of the constitutive relations, which relate displacement, stress, and electric field. Finally, we find a mathematical relation for the piezoelectric transducer excitation in order to annihilate the transducer force. A static and a frequency‐dependent approximate solution for the transducer actuation signal are derived. The latter solution reduces the inner force drastically in a certain frequency range. After numerical results for the force‐control algorithm are presented, we finally experimentally verify our theory: First, the force‐controlled configuration is exposed to a monofrequent harmonic excitation test run for 30 min, showing no sign of fatigue or material failure, because the transducer force is below the ultimate tensile strength. Then, the system is excited by the same harmonic excitation again, but the control signal for the piezoelectric transducer is turned off. The result is a visible damage of the piezoelectric transducer, leading to a significant change of the first eigenfrequency.

Advantage of surgical intensive care unit (SICU) predominant by cardiothoracic surgeons in multiple trauma management in a primary hospital

“…Multiple trauma patients sustained uncontrolled bleeding should be treated following damage control theory. 12 Damage control theory which contains damage control surgery and damage control resuscitation emphasizes on temporary control of bleeding and further contamination instead of giving definitive surgery to patients or conducting resuscitation. At the same time, damage control theory requires to control hemorrhage, maintain circulating volume and correct the “lethal triad” of acidosis, coagulopathy and hypothermia until definitive intervention is appropriate.…”

A Review: Structural Shape and Stress Control Techniques and their Applications

“…SOAP considers the residual stresses generated in the structure when the actuators are activated, and it minimizes the residual stresses by optimizing the actuator placement [69]. Piezoelectric actuators nullify the axial force in members in a one-dimensional structure [70].…”

Piezoelectric Materials in Civil Engineering Applications: A Review

“…54 Schoeftner et al ( 2019) actuated a piezoelectric transducer to reduce the dominant stress to zero in a one-dimensional bar, by using the feed-forward technique. 55 They transformed the two-degree freedom equations of motion and created into differential equations related to displacement, voltage, and electric field. They developed a static-and frequencydependent mathematical model to activate the piezoelectric transducer.…”

“… Suggested dynamic model to control stress: (a) the geometry of the system, (b) the dynamic model of the system. Reprinted with permission from ref ( 55 ). Copyright 2019 Wiley.…”

“… Experimental setup for the single frequency harmonic test. Reprinted with permission from ref ( 55 ). Copyright 2019 Wiley.…”