High-Speed Multiplexed Fiber Optic Sensing for Extreme Dynamic Loading Events

Advanced Damage Detection though Optical sensor Network

High-Speed Multiplexed Fiber Optic Sensing for Extreme Dynamic Loading Events

Authors: J. Mertes, M. Haverdings, R.Evenblij, Technobis

Composite structures comprise large parts of modern aircrafts, as they are low in weight in provide strength superior to commonly used metallic structures. However, the complexity of the material demands for novel Structural Health Monitoring (SHM) techniques in order to accurately monitor the state of the material and make statements about lifetime and behavior [1]. In recent years, efforts were made to integrate sensors such as fiber-Bragg gratings (FBG)into composite structures. Their advantage over other SHM sensors are their small size and light weight, immunity to electromagnetic interference and multiplexing capabilities [2]. SHM applications with FBGs are often restricted by the optical interrogation of the sensors, where compromises between sampling frequency, resolution and dynamic range have to be made. In particular, high speed interrogators are limited to strain measurements of only few tens of με and complicated tuning schemes have to be employed to overcome these limitations [3,4].Previously, we demonstrated an interrogator with superior dynamic range of 1,000με, while allowing for 1MHz sampling speed and high strain sensitivity measurements of smaller than1με [5]. The interrogator is based on a small-scale demultiplexed Mach-Zehnder interferometer (DMI) manufactured on a photonic integrated chip. In this work, we showcase the multiplexing capabilities of the tool by monitoring an array of multiple sensors to capture impact events. The impact location is determined from the measured strain data via a Time Difference Of Arrival (TDOA) algorithm. The results show good accuracy and prove the suitability of newly developed interrogator for this SHM task.

2019 ICCST/12 – 12th International Conference on Composite Science and Technology
Sorrento, Italy, 8-10 May 2019

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