( SE18--1114) SURVIVABILITY OF SILICONE ENCASED FIBER BRAGG GRATINGS SUBJECT TO HIGH RATE IMPACTS

摘要

Measurement of the back-face deformation versus time is an important parameter when assessing injury for personal protection systems. The high strain to failure of Kevlar~Rlimits the types of sensors that would be able to survive if they were embedded. Fiber Bragg gratings (FBGs) on paper can withstand these types of strains, however, their brittle nature prevents them from surviving after being embedded into a personal protection system. To overcome this, the FBG sensor is held inside of a sensing layer between a Kevlar~Rshot pack and clay backing material. To ensure the sensor survives the impact, there must be relative slip between the FBG and the encasing material but not too much that the sensor misrepresents the shot pack deformation. Silicone has been investigated as an alternative encasing material to increase survivability of the fibers and repeatability of the strain history profile. Silicone offers a lower elastic modulus over Kevlar~Rwhich results in less energy transfer to the FBG and a lower impact on the overall deformation. This property allows greater deformation in the FBG while increasing the sensor's survivability. Three different silicone mixes for the sensing layer were tested at thicknesses of 1 mm and 2 mm, and the resulting damages to the FBG were compared. The results will be used to optimize future FBG sensing layers for better sensor preservation during high velocity, high strain rate impacts.