Laser induced graphene for in situ damage sensing in aramid fiber reinforced composites

In situ monitoring of strain and damage in fiber-reinforced composites provides critical information regarding the state of the material without requiring the structure to be removed from operation. In order to avoid the use of complex, heavy, and bulky sensor networks to track the state of the structure, recent focus has turned to multifunctional materials with inherent characteristics which enable in situ monitoring. This work investigates laser induced graphene (LIG) integrated within aramid fiber reinforced composites for damage and strain sensing during mechanical loading. The LIG used here fully integrates the sensing material within the composite as the piezoresistive graphene layer is coated directly onto the reinforcing aramid fabric prior to infusing the fibers with the supporting matrix. The sensing element is thus not susceptible to environmental effects and adds no extra weight while also maintaining the specific strength of the material. As strain and damage occur within the composite, the LIG proves capable of tracking strain and detecting plastic deformation in situ. Thus, the result of this work is the integration of a multifunctional component into aramid composites which possesses in situ sensing capabilities. Furthermore, the processes and materials are easily scalable for the large-scale production of multifunctional aramid fiber reinforced composites.