Displacement field estimation for a two-dimensional structure using fiber Bragg gratingsensors

Abstract

The structure shape itself is of great interest for many aerospace applications. For example,the stability of the surface shape of large, high precision or space reflectors isessential for the communication performance. The knowledge of static and dynamicdisplacements of these structures would provide the possibility to enhance theirperformance by appropriate countermeasures. During operation, however, the directmeasurement of displacements of the whole structure is often difficult. This studyinvestigates whole displacement field estimation using strain measurement and adisplacement–strain-transformation approach. The use of fiber Bragg gratings (FBGs) asstrain sensors for this application offers the possible implementation of an integrated sensornetwork including many measurement points within only a few optical fibers.This paper discusses many issues related to the displacement field estimation ofa dynamically excited plate using a transformation matrix based on a modalapproach. In order to reduce systematic displacement estimation errors due toaliasing, a parametric study was performed and the sensor locations were optimized.Experimental validation was also conducted using a cantilever plate equipped with 16FBG sensors in an optimized configuration. The estimated displacements showedgood agreements with those measured directly from laser displacement sensors.