Ground tests on a wing of an aircraft model using fiber optic sensors

This paper concerns the use of fiber optic sensors for performing an experimental modal analysis in a wing of an aircraft model. Modal analysis can be used as a tool for checking the structural integrity of structures, in other words it can be used in a new branch of non destructing testing called Structural Health Monitoring (SHM). The objective of this paper is preliminary to the design of an SHM system for aeronautical structures. An SHM system is typically constituted by: integrated sensors, a system for data acquisition and an expert system for damage assessment. In this work the last part is not treated. The sensors used are the Fiber Bragg Gratings that have been embedded in the skins of the wing. Time domain response of the fiber optic sensors induced by impact hammer are acquired and transformed into the frequency domain. Using classical modal analysis techniques the first two strain mode shapes of the wing are determined from the Strain Frequency Response Functions. Also an accelerometer has been used to retrieve the mode shapes. Finally the results from a finite element model have been compared with the experimental results.