Prediction Of Mechanical Properties For CNTs/CF Multi-scale Wind Turbine Blade Composites

Wind turbine blade composites with higher strength and stiffness are required asthe development trend of large-scale, lightweight and oceanic blades. A newopportunity has been provided for the development of wind turbine blade compositesbecause of the discovery of carbon nanotubes with excellent performance. Chemicalvapor deposition method is usually used to grow carbon nanotubes in situ on thesurface of carbon fiber to prepare a carbon nanotubes/carbon fiber multi-scalereinforcement which not only can effectively solve the dispersed defect of carbonnanotubes in matrix, also improve the mechanical properties in the transversedirection of multi-scale composites and interface bond strength between carbon fiberand matrix owing to the radial distribution of carbon nanotubes on the surface ofcarbon fiber. Based on asymptotic homogenization theory, the effective properties ofmulti-scale wind turbine blade composites are predicted by calculation programwritten by ANSYS/APDL and multi-scale models to provide a basis for theapplication of carbon nanotubes in the blade materials.First, the two dimensional prediction model of the effective mechanicalproperties for carbon nanotubes/carbon fiber multi-scale wind turbine bladecomposites is established. Using two-scale homogenization method, the influencerules of material parameters (the length, diameter, and elastic modulus of carbonnanotubes; the diameter, elastic modulus and packing modes of carbon fiber; theelastic modulus and Poisson’s ratio of matrix; the thickness, volume fraction, elasticmodulus and Poisson’s ratio of interface) on the effective properties of multi-scalewind turbine blade composites are analyzed by ANSYS/APDL calculation program. Ithas been found that the effective properties of wind turbine blade composites aregreatly reinforced by carbon nanotubes in situ on the surface of carbon fiber. As themain supporting body of the multi-scale composites, the reasonable dimension andpacking modes of carbon fiber can greatly improve the effective properties ofmulti-scale composites. The appropriate matrix can improve the equivalent propertiesof composites. The interface between carbon nanotubes and matrix has little effects onthe effective properties of composites.Second, the prediction model of the effective mechanical properties for wavy carbon nanotubes/carbon fiber multi-scale wind turbine blade composites isestablished. The influence rules of the bending parameters (the amplitude, wavelength,diameter and volume fraction) for carbon nanotubes on the effective properties ofmulti-scale wind turbine blade composites are analyzed. The results show that thewaveform of carbon nanotubes has a certain effect on the effective mechanicalproperties of multi-scale wind turbine blade composites.The results have certain guiding function for the application of carbonnanotubes/carbon fiber multi-scale composites in wind turbine blade.