computed the correlations between the impact response and the impulse response function in training data using the time reversal concept to localize impact on a composite wing structure. Impact localization on composite materials can be done using several techniques, ,,.
Several studies have been performed to demonstrate the feasibility of using FBG sensors for SHM applications,. Moreover, one of the key advantage of FBG sensors is that large number of measurement points can be multiplexed in one optical fiber line, which is beneficial to minimize the wiring issues involved with SHM of large-scale structures. Among various types of sensors, FBG sensors are highly attractive for SHM application because of their advantages such as immunity to electromagnetic interference, small size, lightweight and they can be embedded into composite structures. There are several different kinds of sensors available for SHM application such as piezoceramic, , and fiber optic based sensors. SHM is done using attached or embedded sensing technologies to monitor the safety and integrity of the structure. Therefore, real-time structural health monitoring (SHM) of aircraft structures to detect and locate these low velocity impacts can be crucial to alerting ground engineers to inspect for BVID occurrence. This is of particular concern to the aerospace industry since these materials are being increasingly used for manufacturing various aircraft components. Low velocity impact on structures made of composite materials can cause barely visible impact damage (BVID), which significantly reduce the strength of the composite material. Overall, impacts on the upper and lower surface of the composite wing were predicted and the localization results for three and one FBG sensors were comparable. The feasibility of utilizing the error outlier with weighted MAD threshold algorithm to localize impact with a single sensor was effectively demonstrated. A parametric study was also performed to determine the possibility of localizing impact using a single sensor. The weighted MAD threshold used to filter the likely impact locations from a set of detected locations, and the proposed algorithm was able to localize impacts with consistent overall performance for a varying number of allowed detected locations.
Impact monitoring was performed with three multiplexed FBG sensors and the data acquisition was done using SFI-710 high speed interrogator to obtain the impact response signal at a frequency of 100 kHz. The error outlier with MAD threshold algorithm was used to localize impacts on a 1000 mm × 1400 mm area of the upper and lower surfaces of a Jabiru UL-D composite wing. In this paper, a low velocity impact localization algorithm based on an error outlier assessment technique with weighted Median Absolute Deviation (MAD) threshold was developed to localize impact on complex composite structures.
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