Multifunctional Carbon Nanotubes Enhanced Structural Composites with Improved Toughness and Damage Monitoring

Abstract

The potential of carbon nanotubes (CNT) as multifunctional filler in poly(epoxy)-based structural composites has been investigated. In a first step the reinforcement effect of CNT has been studied by tensile and three points bending tests, which evidenced significant improvements of stress and strain at break (respectively +17% and +30% for tensile tests on unidirectional carbon fibre-epoxy composites). Moreover, fracture experiments have also revealed a positive effect of CNT on the toughness (G1c) of carbon fibres-epoxy composites (+105% of improvement at the initial stage). In a second step, the health monitoring capability quantum resistive strain sensors (sQRS) made of CNT filled epoxy nanocomposite, incorporated in the core of glass fibres-epoxy composites has been studied. It was shown that during cyclic tensile tests, following the evolution of the relative resistance amplitude (Ar) of sQRS with strain gives a pertinent information on non-reversible phenomena such as plastic deformation and cracks’ development within the composite. In particular, the evolution of the sQRS sensitivity (gauge factor GF) under and over the elastic limit, allows to track damage accumulation throughout the composite. These results suggest a possible use of sQRS for the structural health monitoring (SHM) of composites in fields such as boating, wind energy, aeronautics and automotive.

Improving through‐thickness conductivity of carbon fiber reinforced polymer using carbon nanotube/polyethylenimine at the interlaminar region

“…The electron transfer is greatly improved at the closest conductive areas between the carbon fibers' layers. In a CNT network, the main conduction mode is tunneling conductivity, 42–44 that explains the logarithmic relationship between conductivity and CNT loading, as the latter directly influences the minimal interparticle distance between the CNT 45 …”

“…In a CNT network, the main conduction mode is tunneling conductivity, [42][43][44] that explains the logarithmic relationship between conductivity and CNT loading, as the latter directly influences the minimal interparticle distance between the CNT. 45 Allaoui and Zeng 14,41 studies reported that the CNT percolation threshold ranged from 0.5 to 2.5 wt%. In fact, the uniformity and dispersion of the CNT can significantly influence the percolation threshold.…”

Coupled Flexural-Electrical Evaluation of Additively Manufactured Multifunctional Composites at Ambient Temperature

“…Three-point bend testing was conducted on traditionally fabricated multifunctional carbon nanotubes, enhanced structural composites for improved toughness, and damage monitoring. Reinforcement effects of the multifunctional carbon nanotubes enhanced structural composites were structurally investigated via tensile and three-point bend testing, which led to significant improvement of stress and strain at failure [13]. This study also included the assessment of the structural health monitoring capability via the use of quantum resistive strain sensors made up of carbon nanotubes filled epoxy nanocomposite embedded at the core of the glass fiber-epoxy composites [13].…”

“…Reinforcement effects of the multifunctional carbon nanotubes enhanced structural composites were structurally investigated via tensile and three-point bend testing, which led to significant improvement of stress and strain at failure [13]. This study also included the assessment of the structural health monitoring capability via the use of quantum resistive strain sensors made up of carbon nanotubes filled epoxy nanocomposite embedded at the core of the glass fiber-epoxy composites [13]. While the electrical characterization is mentioned, the electrical conductivity is not included in this research [13].…”

“…This study also included the assessment of the structural health monitoring capability via the use of quantum resistive strain sensors made up of carbon nanotubes filled epoxy nanocomposite embedded at the core of the glass fiber-epoxy composites [13]. While the electrical characterization is mentioned, the electrical conductivity is not included in this research [13]. Also, the coupled flexural-electrical evaluation of additively manufactured multifunctional composites at ambient temperature was not addressed [13].…”