PSI - Issue 68

J.M. Parente et al. / Procedia Structural Integrity 68 (2025) 160–165 J.M. Parente et al. / Structural Integrity Procedia 00 (2025) 000–000

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resistance, a trend that persists in subsequent cycles. On the other hand, the results of the incremental cyclic relaxation tests show that the electrical resistance response changes when a mechanical load is applied. During the relaxation period between cycles, the electrical resistance initially decreases, followed by stabilization, a behaviour that is more pronounced for longer stabilization periods, which is in line with the studies developed by Tamburrano et al. (2013).

6,00E+04 7,00E+04 8,00E+04 9,00E+04 1,00E+05 1,10E+05

(Ω/sq)

eletrodes on the top eletrodes on bottom

Average surface resistivity

0,75 CNT

0,5 CNT

0,375 CNT 0,375 GNP

0,25 CNT

0 GNP

0,25 GNP

0,5 GNP

Fig. 4. Surface resistivity for different GNP and CNT weight contents .

Fig. 5. Representative mechanical (red) and piezoresistive (blue) results for nanocomposites: a) with increasing bending strength; b) increasing stabilization time between cycles. 4. Conclusion This work analyzed the effect of nano-reinforcement hybridization, with a particular focus on the combination of carbon nanotubes (CNTs) with graphene nanoparticles (GNPs), on the mechanical performance and piezoresistive sensitivity of epoxy-based nanocomposites. The results showed that the synergistic effects of hybridization outweigh the use of single nano-reinforcements, offering improvements in bending strength, stiffness, and piezoresistive gauge factor. The optimum combination of 0.25 wt.% GNP and 0.5 wt.% CNT resulted in the most pronounced mechanical and piezoresistive improvements, due to the complementary geometries and properties of the nanomaterials. These results suggest that hybrid nano-reinforcements are very promising for advanced applications in structural components and sensors, providing the development of multifunctional and high-performance materials. Further research into the