M3D aerosol jet printed buckypaper multifunctional sensors for composite structural health monitoring

Sensors placed along various stages of manufacturing processes can identify errors and ensure the quality of a product. Specially, sensors are becoming essential for more complicated composite fabrication due to coupling together heat transport, curing kinetics, resin rheology and flow as well as pressure effects. In this research, embedded composite sensor fabrication, maskless mesoscale materials deposition system has been used to print electrically conductive silver patterns on the carbon nanotube (CNT) sheets or buckypaper (BP) to measure its resistance change, and thus used as embedded sensors in composite laminates for both manufacturing process and structure health monitoring. Three different samples of nanotube sheets were used in this work and compared. The samples exhibited slightly different behaviors in terms of resistive response during the resin infusion and curing process with vacuum bagging, yet also demonstrated similar patterns, which indicated their sensing capabilities. Upon the resin flow, the sensor resistance dropped similar to 20-30% from the initial value, then increased up to 120-145% compared to its minimum value at the final curing stage. After curing process, embedded sensors could monitor the impact or structural deformation of a composite part.