AbstractAs an emerging material, nanomaterials have attracted extensive attention due to their small size, surface effect and quantum tunneling effect, as well as potential applications in traditional materials, medical devices, electronic devices, coatings and other industries. Herein, the influence of nanoparticle selection, production process, grain size, and grain boundary structures on the mechanical properties of nanomaterials is introduced. The current research progress and application range of nano-materials are presented. The unique properties of nano-materials make them superior over traditional materials. Therefore, nanomaterials will have a broader application prospect in the future. Research on nanomaterials is significant for the development and application of materials science.

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Abstract:The thermal conductivity of a graphene coating for anti-/deicing is rarely studied. This paper presents an improved anti-/deicing efficiency method for composite material anti-/deicing by using the heat-transfer characteristic of a graphene coating. An anti-/deicing experiment was conducted using the centrifugal force generated by a helicopter rotor. Results showed that the graphene coating can accelerate the internal heat transfer of the composite material, thereby improving the anti-icing and deicing efficiency of the helicopter rotor. The spraying process parameters, such as coating thickness and spraying pressure, were also studied. Results showed that reducing coating thickness and increasing spraying pressure are beneficial in preparing a graphene coating with high thermal conductivity. This study provides an experimental reference for the application of a graphene coating in anti-/deicing.

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a b s t r a c tConducting a further analysis on loading sharing among compound planetary gear system in wind turbine gearbox, and making a meshing error analysis on the eccentricity error, gear thickness error, base pitch error, assembly error, and bearing error of wind turbine gearbox respectively. In view of the floating meshing error resulting from meshing clearance variation caused by the simultaneous floating of all gears, this paper establishes a refined mathematical model of two-stage power split loading sharing coefficient calculation in consideration of multiple errors. Also obtains the regular curves of the load sharing coefficient and floating orbits of center gears, and conducts a load sharing coefficient test experiment of compound planetary gear system to verify the research results, which can provide scientific theory evidence for proper tolerance distribution and control in design and process. Compound planetary gear system is widely used in the field of wind turbine gearbox, aeronautics and other special precision transmission system. The RENK and SANY company adopts compound planetary gear system used in its wind turbine as main gearbox. Compound planetary gear system uses multiple double planet gear with fixed axes for load sharing. Planet gear does not revolve but rotate, featured in power split, high transmission power, and one-side force bearing. Compound planetary gear system can avoid simultaneous mesh with sun gear and annular gear, instead breaking it down into two stages of external gearing and internal gearing, which can overcome traditional planetary gear transmission's bearing of alternating load, intermittent lubrication between planetary gears and bearings, and centrifugal forces caused by the rotation of planet carrier. The wind turbine gearbox using two-stage and fixed axes gear train with unilateral mesh brings greatly improved strength, stiffness, working life as well as reliability of the system. Scholars from both home and abroad have been constantly exploring and studying planetary gear system load sharing behaviors, and the research findings are as follows. Hidaka T et al. studied the relationship between error and load-sharing in planetary gear transmission [1]; Ma et al. probed into the effects of gear errors on planetary transmission [2]; Krantz et al. discussed the characteristics of load sharing of power-split transmission [3,4]; Kahraman focused on the characteristics of load sharing of planetary gear transmission from the perspective of statics [5e10]; Singh et al. established the analysis model on the characteristics of load sharing of planetary transmission [11,12]; Carlos et al. elaborated on the solutions to load distribution on gear teeth [13]; Zhu Rupeng et al. delved into the characteristics of load sharing of planetary and Encased Differential Herringbone Train transmission systems from the perspective of statics [14,15]; Fang zongde et al. studied the load-sharing characteristics of planetary and two-way power-split gear system [16,17]; Mo Shuai et al. devel...

Abstract:The deformation of aeronautical monolithic components due to CNC machining is a bottle-neck issue in the aviation industry. The residual stress releases and redistributes in the process of material removal, and the distortion of the monolithic component is generated. The traditional one-side machining method will produce oversize deformation. Based on the three-stage CNC machining method, the quasi-symmetric machining method is developed in this study to reduce deformation by symmetry material removal using the M-symmetry distribution law of residual stress. The mechanism of milling deformation due to residual stress is investigated. A deformation experiment was conducted using traditional one-side machining method and quasi-symmetric machining method to compare with finite element method (FEM). The deformation parameters are validated by comparative results. Most of the errors are within 10%. The reason for these errors is determined to improve the reliability of the method. Moreover, the maximum deformation value of using quasi-symmetric machining method is within 20% of that of using the traditional one-side machining method. This result shows the quasi-symmetric machining method is effective in reducing deformation caused by residual stress. Thus, this research introduces an effective method for reducing the deformation of monolithic thin-walled components in the CNC milling process.

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