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Wind energy has been regarded to be one of the renewable energies to rely on for the future. In tropical countries like India maintenance of wind turbine blades is a challenging task. Solid particle erosion is one of the root causes of wind turbine blade damage resulting in reduction in energy production. In the present study, in-house synthesized ceramic oxide nanoparticles such as Al 2 O 3 , ZrO 2 , and CeO 2 are used as fillers for reinforcement of water-based polyurethane (PU) coatings on glass fibre reinforced polymer (GFRP) substrates for solid particle erosion resistance for the first time. Al 2 O 3 , ZrO 2 , and CeO 2 nanoparticles have been prepared by solution combustion synthesis method using urea, glycine, and oxalyl dihydrazide, respectively, as fuels. These ceramic nanoparticles are found to crystallize in corundum, tetragonal, and cubic structures, respectively, as confirmed by X-ray diffraction studies. Field emission scanning electron microscopy shows the porous microstructure of the oxide products due to the release of gases in course of preparation. Transmission electron microscopy studies of these nanoparticles show corresponding lattice fringes in their high-resolution images. Observed Al–O, Zr–O, and Ce–O vibrational modes in Raman spectra confirm the formation of corresponding oxides. The oxidation states of Al, Zr, and Ce in the respective oxides are found to be +3, +4, and +4, respectively, as demonstrated by X-ray photoelectron spectroscopy. The nanocomposite coatings consisting of PU and Al 2 O 3 , ZrO 2 , and CeO 2 nanoparticles have been developed by a simple spray method on GFRP substrates. The solid particle erosion resistance tests of coatings have been studied at varied concentrations of Al 2 O 3 , ZrO 2 , and CeO 2 nanoparticles at impinging angles of 30° and 90°. It has been observed that ZrO 2 , and CeO 2 nanoparticles-reinforced PU coatings show better solid particle erosion resistance compared to Al 2 O 3 -reinforced coating. Among different concentrations studied here, coatings with 15 wt% filler concentrations offer a relatively low erosion rate than the other concentrations at both impinging angles. However, GFRP substrate and PU coating are observed to show much higher erosion rate compared to nanoparticles reinforced PU coatings. [ABSTRACT FROM AUTHOR]

Wind energy is a non polluting cost-effective renewable energy source. Wind power technology in India has grown significantly in the last decade. Capacity of wind turbines has been increased significantly and at the same time, the cost of generating power from wind has come down. The blades used in the wind turbine are of composite material with aerodynamic profile, twisted tip and varying thickness along its length. Composite wind turbine blades are observed to fail due to matrix compression. Available failure theories are not capable of predicting the maximum stress in transverse compressive-shear stress region. Hence a new set of failure criteria for predicting the failure of composite wind turbine blades is proposed. The criterion is examined with both unidirectional and bidirectional experimental results for wind turbine blade material. The results of failure prediction of unidirectional lamina and multi directional laminate are encouraging. The stress strain prediction is also compared with experimental data sets. The proposed criterion is compared with the criterion proposed by the participants of World wide Failure Exercise (WWFE). The criterion is further extended to composite laminate using classical lamination theory and ply by ply discount procedure using specially designed coding (FPCL). The coding accepts the effect of non linearity and thermal effects. Using the coding it is possible to predict initial and final failure, delamination and mode of failure. The criteria are also applied to the various test results presented in WWFE. The satisfactory results arrived from modified criterion. The error in predicting the failure is tabulated and compared with other's predictions. [ABSTRACT FROM AUTHOR]