Practical method for localizing low-velocity impact on a UAV composite wingbox structure under loading conditions

Abstract

A low-velocity impact event can produce undetectable damages inside laminated composite structures. Such damages have been introduced as one of the main causes of catastrophic failure of whole structure, thus impact event detection and localization should be essential for many kinds of composite structures. In this study, low-velocity impact localization method was proposed using six multiplexed fiber Bragg grating (FBG) sensors on the composite wingbox structure. The principle is to find the location which has the most similar set of reference signals from the database. Firstly, the required reference signals were measured to construct the database for the test section which is located on the upper skin of the wingbox. Then, the localization was implemented with the process of detecting the time of arrival (TOA) and finding the impact location. The similarities between the impact-induced signals and reference signals are assessed by calculating the root mean squared (RMS) values. Through the impact localizations on the non-reference locations, this method was validated. Also, this method was applied to the impact localizations when the wingbox structure was under static loads. From the acceptable results of such experiments under static loading conditions, the practicality of this method was successfully verified.