Virtual Reference Approach for Dynamic Distributed Sensing of Damage in Large Structures

Abstract

A reference-free damage detection method based on distributed monitoring of strains in large structural systems is introduced. The method employs the dynamic distributed strain data to formulate its own virtual reference state for detection of defect locations. It uses a single line of optical fiber by way of a dynamic pulse-prepump (amplitude transfer) Brillouin scattering technique in order to acquire dynamic distributed strain data. An experimental program was designed to evaluate the performance of the proposed methodology. The experiments involved dynamic tests of a long beam with simulated defects with small opening displacements ranging between 50 and 550 μm. The implications of this approach are significant since it enables the structure to be monitored at any stage during its service life without the need for prior reference data.