Localizations and force reconstruction of low-velocity impact in a composite panel using optical fiber sensors

A new approach of monitoring low-velocity impact events on composite structures was presented and experimentally evaluated. In this approach, impact strain histories of a composite plate were measured with optical fiber sensors. The recorded signals were used to estimate locations and forces of low-velocity impact events. For experimental validation, four-sensor heads were surface mounted at the four corners of a composite panel. The optical sensors caught dynamic strain due to impacts on the panel, and the optical cables transmitted wavelength changes of the sensors. The multiplexed wavelength changes were measured using a high-speed fiber Bragg grating interrogator for the determination of impact location. The locations of impact events were estimated using a neural network program and measured signals. The estimated locations and converted strain signals were taken as the inputs to the process of reconstructing impact forces. Even though the current study is an initial investigation on a simple impact problem, the result shows the possibility that the proposed technique can be applied to low-velocity impact monitoring of general composite structures.