Abstract

Strengthening composite structures for advanced industries such as offshore wind generation is a real issue. Due to the huge dimensions expected for next generation wind-blades, composites based on glass fibers can no longer be used due to the lack of stiffness, whereas composites based on carbon fibers are expensive. Therefore, switching to alternative structural solutions is highly needed. This might be achieved by appropriate use of carbon nanotubes (CNTs) either as fillers of epoxy matrices, especially in inter-plies, or as fillers of epoxy glues used in structural bonding joints. As an example, trailing edges of offshore wind-blades are addressed in the current article, where monolithic bonding holds together the two structural halves and where the risk of sudden and brittle separation of edges while wind-turbines are in service is quite high. This can lead to tedious and very expensive maintenance, especially when keeping in mind the huge dimensions of new generation wind turbine blades that exceed lengths of 100 m. Bond joints and composites inter-plies of the final CNT-reinforced structures will exhibit stiffness and toughness high enough to face the severe offshore environment. In this article, multiscale Finite Element (FE) modeling is carried out to evaluate mechanical properties following the addition of CNTs. To achieve an optimal reinforcement, the effect of inclination of CNTs vs. mechanical loading axis is studied. Two innovations are suggested through this numerical study: The first consists of using homogenization in order to evaluate the effects of CNT reinforcement macroscopically. The second innovation lies in this forward-looking idea to envisage how we can benefit from CNTs in continuous fiber composites, as part of a deep theoretical rethinking of the reinforcement mechanisms operating at different scales and their triggering kinetics. The presented work is purely numerical and should be viewed as a “scenario” of structural composite materials of the future, which can be used both in the offshore industry and in other advanced industries. More broadly and through what is proposed, we humbly wish to stimulate scientific discussions about how we can better improve the performances of structural composite materials.

Highlights

  • IntroductionReinforcement of composite bonding joints by carbon nanotubes (CNTs)-reinforced resin, which will result in higher bonding strength, and improve joints’ toughness

  • Licensee MDPI, Basel, Switzerland.To significantly improve the performance of smart composites [1,2,3], the current article work assesses the benefits of carbon nanotubes (CNTs) as fillers to epoxy resin by way of a numerical multiscale method simulation

  • On the basis of the results presented along with a deep step-back thinking, it seems rather improbable, if not impossible, that the composite whose matrix is reinforced by carbon nanotubes, on one hand, and continuous fibers, on the other hand, could benefit fully from nanometric reinforcement

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Summary

Introduction

Reinforcement of composite bonding joints by CNT-reinforced resin, which will result in higher bonding strength, and improve joints’ toughness. Chirality and functionalization have been studied through atomic simulation, 2) Reinforcement of composite bonding joints byisCNT-reinforced resin, whichforces. Will rewhere the interface between the CNT and matrices governed by Van der Waals sult in higher bonding strength, and improve joints’ toughness. The effect of CNT orientation vs the loading direction is studied. FRP composite scale, hopin a way to show proof of concept of toughness improvement at the laboratory ing that mastering inclination techniques can be achieved soon, industrially. Chirality and functionalization have been studied through atomic simulation, where the interface between the CNT and matrices is governed by Van der Waals forces. In the Structure current article, the effect of CNT orientation vs the loading direction is studied

Atomic of CNTs
Atomic Structure of CNTs
Modeling CNTs and CNT–Matrix Interface
Theory
Homogenization
Influence
Tension and Compression
Torsion angle Φ loads
Shear Test
16. Increase
17. All matrix sections are maximum stress
Macroscopic
Macroscopic Stiffness Tensor of the Nanocell s sion
20. Illustration of the longitudinal section of the mesh of 1the
Synthesis and Discussions
Observations about Engineering Use
Observations about Engineering
10. Prospective
11. Further Thinking
12. Conclusions
Full Text
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