No abstract

No abstract

This work is aimed at the development of finite element models and prediction of the mechanical behavior of MXene nanosheets. Using LS-Dyna Explicit software, a finite element model was designed to simulate the nanoindentation process of a two-dimensional MXene Ti3C2Tz monolayer flake and to validate the material model. For the evaluation of the adhesive strength of the free-standing Ti3C2Tz-based film, the model comprised single-layered MXene nanosheets with a specific number of individual flakes, and the reverse engineering method with a curve fitting approach was used. The interlaminar shear strength, in-plane stiffness, and shear energy release rate of MXene film were predicted using this approach. The results of the sensitivity analysis showed that interlaminar shear strength and in-plane stiffness have the largest influence on the mechanical behavior of MXene film under tension, while the shear energy release rate mainly affects the interlaminar damage properties of nanosheets.

Real-time strain monitoring of large composite structures such as wind turbine blades requires scalable, easily processable and lightweight sensors. In this study, a new type of strain-sensing coating based on 2D MXene nanoparticles was developed. A Ti3C2Tz MXene was prepared from Ti3AlC2 MAX phase using hydrochloric acid and lithium fluoride etching. Epoxy and glass fibre–reinforced composites were spray-coated using an MXene water solution. The morphology of the MXenes and the roughness of the substrate were characterised using optical microscopy and scanning electron microscopy. MXene coatings were first investigated under various ambient conditions. The coating experienced no significant change in electrical resistance due to temperature variation but was responsive to the 301–365 nm UV spectrum. In addition, the coating adhesion properties, electrical resistance stability over time and sensitivity to roughness were also analysed in this study. The electromechanical response of the MXene coating was investigated under tensile loading and cyclic loading conditions. The gauge factor at a strain of 4% was 10.88. After 21650 loading cycles, the MXene coating experienced a 16.25% increase in permanent resistance, but the response to loading was more stable. This work provides novel findings on electrical resistance sensitivity to roughness and electromechanical behaviour under cyclic loading, necessary for further development of MXene-based nanocoatings. The advantages of MXene coatings for large composite structures are processability, scalability, lightweight and adhesion properties.

The potential of particle and fiber reinforced anti-erosion coatings for the protection of wind turbine blades is explored through computational modelling. A hypothesis that stiff disc-shaped particle or fiber reinforcements embedded in viscoelastic coatings ensure better erosion protection is validated numerically, and mechanisms of this effect are analyzed. A computational unit cell model of coatings with embedded fibers (fiber pulp) or disc particles subject to rain droplet impact is developed, and series of computational experiments is carried out. The distribution and scattering of stress waves from the rain droplet impact and damping properties are analyzed for homogeneous viscoelastic polyurethane coatings, coatings with discshaped particles, and fiber pulp. It is shown that the stress waves are increasingly scattered, and the damping is increased with higher volume percentage of the fibers. The mechanism of such increased energy dissipation is found to be related to the high local viscoelastic deformation in the regions between closely located fibers and the higher stiffness of the unit cell. The current work demonstrates the high potential of fiber engineered coatings for the improvement of anti-erosion protection of wind turbine blades.