Damage Localization From Sensor and Actuator Data

Abstract

Integrated sensor systems are becoming more prevalent in structures for the purpose of structural health monitoring (SHM). A limiting factor for many current SHM methods is that in order to locate damage, modeling of the structural response is required. The structural model can introduce significant errors, in addition to those in the sensor data, both through limitations in the mechanical models and manufacturing variations. This work presents a method of localizing damage that eliminates the requirement for an independent structural model. The method is based on generating flexibility parameters of the structure in pre- and post- damage states. In order to determine these parameters, a technique of loading the structure at each sensor location with actuators and subsequently measuring the displacement at all sensors has been developed. This allows the required information to be constructed from only sensor and actuator data. From the sensor data, a set of damage location vectors are determined. These vectors allow one to localize damage in one of two ways. The first analysis reapplies each set of damage location vectors as applied forces to the structure and locates the lowest regions of stress. The second approach, more applicable to real-time health monitoring, locates the lowest values of the damage location vectors. Both techniques have the ability to locate progressive damage. Simulations on a plate structure are performed for two sensor meshes (eight and thirty-two sensor locations). The results demonstrate excellent damage localization, and some indication of damage severity. Finally, an experimental demonstration of the method utilizing eight sensors surface mounted to an aluminum plate is presented for four applied damage cases.