Enhancing Sensitivity of Vibration-based Damage Metrics using Feedback Control: Towards Dual Use Smart Structures

Dartmouth College, Hanover NH

Investigators

Abstract

Laura R. Ray 9988414 Enhancing Sensitivity of Vibration-Based Damage Metrics using Feedback Control: Towards Dual Use Smart Structures This project explores methods of enhancing sensitivity of modal properties to local damage in order to detect damage noninvasively and autonomously in smart structures. Smart structures contain embedded or surface mounted sensors and actuators that are normally used for vibration or acoustic control. Developing and demonstrating methods by which these components can also be used to diagnose and localize structural degradation due to damage is the primary objective of the project. A second objective is to integrate damage detection and active vibration control in order to develop multifunctional smart structures. Choice of the control system, which encompasses determining an appropriate control model of the structure, quantifying nominal uncertainty, selecting number of and placement of actuators and sensors, and choosing a compensator, is investigated in the context of each objective. Vibration-based damage detection is complicated by the small sensitivity of modal metrics to local damage. The hypothesis of the project is that careful selection of control laws for actuating the structure can enhance observability of local parameter variations induced by damage. An analytic framework for designing sensitivity enhancing control laws and for integrating such systems with vibration damping objectives is developed using optimization. Proposed metrics targeted for sensitivity enhancement include modal frequencies, mode shapes, and electromechanical impedance. Experimental efforts focus on demonstrating sensitivity enhancing control for plate structures constructed from homogeneous materials. The methods under development have application to autonomous damage detection and control of flexible structures or substructures. Examples include aerodynamic surfaces, aircraft fuselage, building and bridge substructures (e.g., plates, beams, shells), rotating machinery, and thin-walled pipes. Through assured damage detection methods and multifunctional smart components, the research promotes economical use and development of smart structures in a variety of applications.