Reverse piezo-resistivity of 3D printed continuous carbon fiber/PA6 composites in a low stress range

The 3D printing of carbon fiber reinforced thermoplastics (CFRTPs) is crucial in many fields such as aerospace engineering and electrical motorbikes. Structural health monitoring of 3D printed CFRTPs is important for its practical application. CFRTPs are monitored using the electrical resistance change method, but this method has not been applied to 3D printed CFRTPs. In this study, we used the electrical resistance change method to monitor CFRTPs. The electrical properties were measured in terms of fiber orientation and electrode distance. In addition, a cyclic test was performed to reveal the change in the electrical resistance. Our results reveal that the volume resistance along the 90 degrees orientation has a larger standard deviation than those for the other specimens. The change in resistance exhibited reverse piezo-resistivity at the low stress range in the cyclic tests. The reverse piezo-resistivity occurred due to fiber waviness, which is generated during the 3D printing process.

Automated summary

The study monitored 3D printed CFRTPs using the electrical resistance change method, revealing a larger standard deviation in resistance along the 90 degrees orientation and reverse piezo-resistivity in cyclic tests at low stress ranges.