Estimation of Flexural Properties Degradation in Composite Sandwich Structures using Fiber Bragg Grating Sensors

摘要

The reflective spectrum of fiber Bragg grating (FBG) sensor under axial uniform stresses has a single peak with narrow bandwidth and high reflectivity. But, if the impact-induced damage is generated around FBG sensor attached on the sandwich panel, peak splits can occur due to strain gradient and transverse loading. The detection of the impact-induced damage is very important for structural safety, because this damage can degrade the flexural properties of sandwich panels. From the experiments, the impact-induced damages were detected by using the reflective spectrum change of FBG sensors. Bending stiffness, among the key flexural properties of sandwich panels were measured by 4-point bending test. By matching these results at each experiment, the flexural property degradation of sandwich panels can be estimated after impacts at different energy levels. The survivability of FBG sensors after impact was found to be acceptable, as 11 out of 17 FBG sensors remained intact after the impact test.