Sensor Placement and Structural Damage Identification from Minimal Sensor Information

Abstract

A method of prioritizing sensor locations on a flexible structure for the purpose of determining damaged structural elements from measured modal data is presented. This method is useful in applications where practicality dictates only a small subset of the total structural degrees of freedom can be instrumented. In such cases, it is desirable to place sensors in locations yielding the most information about the damaged structure. No a priori knowledge of the damage location is assumed. The prioritization is based on an eigenvector sensitivity analysis of a finite element model of the structure. In addition, the dual problem is presented and solved, which determines the observability of change in the measured elgenstracture from the instrumented degrees of freedom. This analysis is used to determine the extent to which damage can be localized. An analytical example is presented that illustrates the relationship between the number of measured modes, the number of instrumented degrees of freedom, and the extent to which damage can be localized. Additionally, an analysis of an experimental cantilevered eight-bay truss assembly consisting of 104 elements instrumented with eight single-axis accelerometers is presented. The extent to which structural damage can be localized from the measurement data is limited by the number of measured modes.