Applicability of fiber Bragg grating sensors for cure monitoring in resin transfer molding processes

This article examines the use of fiber Bragg grating sensors for cure monitoring purposes in resin transfer molding processes. Within a resin transfer molding test series a thermoset epoxy-amine resin system was used in combination with a woven flax fiber reinforcement. Particular attention was paid on the location of the optical fiber sensor and its sensitive Bragg grating element inside the mold cavity. Three different installation approaches were tested and the correlation of the corresponding strain response with the actual cure state of the resin system was investigated at 50 degrees C and 70 degrees C isothermal cure temperature, respectively. We could demonstrate that characteristic, conspicuous strain changes are directly related to the sol-gel conversion of the thermoset polymer, which was analyzed considering different approaches for the gel-point detection based on rheological measurements. With the installation of the sensor inside a controllable, capsuled resin volume, we could achieve the most reliable strain response that provides capabilities to give in-situ information of the cure state beyond the gelation point.

Automated summary

This article explores the use of fiber Bragg grating sensors in resin transfer molding processes for cure monitoring, focusing on the correlation between strain response and the actual cure state of the resin system. By testing different installation approaches and analyzing the strain changes related to sol-gel conversion of the thermoset polymer, the study demonstrates the capability of providing in-situ information of the cure state beyond the gelation point with the most reliable strain response achieved by installing the sensor inside a controllable, capsuled resin volume.