Nonlinear behavior mechanism of change in electrical resistance on 3D printed carbon fiber / PA6 composites during cyclic tests

The aim of this paper is to investigate the cause of nonlinear behavior mechanism of change in electrical resistance of 3D printed carbon fiber reinforced plastics (CFRP) due to tensile loading. The electrical resistance change method is a nondestructive testing method that helps detect strain and damage. In previous research for electrical resistance change method applied to 3D printed CFRP, the change in electrical resistance is different compared with the one of conventional CFRP. The behavior makes health monitoring difficult, and the phenomenon needs to be clarified. In this research, we focused on the electrode fabrication method and viscoelasticity effect during cyclic tests. Polishing and laser processing are used as surface treatments for electrode fabrication. Consequently, the treatments are found to affect the reverse piezo-resistivity. In addition, the decrease in electrical resistance depends on the test speeds of cyclic test. The viscoelasticity is found to affect the nonlinear behavior.