Electromechanical behavior of self-sensing composite sandwich structures for next generation more electric aerostructures

The composite sandwich structures being a leading load-bearing aero-structure with embedded sensors for monitoring and diagnosing its own health is a huge step toward next-generation, more electric, well-connected aero-structures. This work presents a unique design of self-sensing sandwich structure comprising active graphene coated glass fabric piezoresistive facesheets bonded to a Nomex (TM) honeycomb core. The piezoresistive response of coated fabrics was recorded throughout the manufacturing process using the vacuum assisted resin transfer molding (VARTM) process. The manufactured sandwich structures were tested under three-point bending and compression loading conditions. The effects of coated fabric sensor position and specimen geometrical parameters (span length, core thickness, and beam width) on piezoresistive response of the beams were evaluated during testing. The piezoresistivity was found to be proportional to the span length and width whereas, an inverse relationship was observed with regards to core thickness. By comparing the effects of spatial position, the bottom sided facesheet showed higher sensitivity than the top facesheet. Finally, the Ramberg -Osgood phenomenological model and exponential growth models were proposed to represent experimental piezoresistivity in three-point bending and compression tests, respectively.