Effect of printing parameters on the mechanical and piezoresistive response of cellular structures manufactured with a conductive polylactic acid nanocomposite through a material extrusion process

The piezoresistive response of specimens made by electrically conductive polylactic acid (PLA) under monotonic and cyclic flexural loading was experimentally investigated. A material extrusion process was utilized to 3D print the conductive PLA/carbon black nanocomposite samples using three infill patterns and three infill ratios. Then three-point bending tests, and electrical resistance measurements, were simultaneously conducted on beam-type specimens. The results of the electromechanical tests demonstrated that the 3D printed samples show outstanding piezoresistive sensing characteristics with excellent cyclic stability and reproducibility suitable for in-situ damage detection and strain monitoring through their electrical resistance change. Determination of gauge factors of specimens with different infill ratios and patterns exhibited a significant sensitivity even at low infill ratio. The potential of the piezoresistive property of conductive PLA/carbon black nanocomposite was examined by proposing 3D printed sensors for strain monitoring. The results demonstrated that conductive feedstock can be successfully processed by this material extrusion technique to develop advanced 3D printing sensing solutions. The applicability of the piezoresistive property of conductive cellular structures 3D printed with PLA/carbon black feedstock as a suitable technique for structural health monitoring was demonstrated.