中文摘要：

为了研究交流电压、低体积分数条件下（〈1350×10-6）水分对SF6气体局部放电及分解特性的影响,搭建了SF6绝缘电力设备实验及检测平台,详细描述了金属突出物缺陷下局部放电量及SOF2、SO2F2、SO2、CO2等4种气体分解产物随水分体积分数的变化规律。结果表明,平均局放量和总体放电量都随水分体积分数呈现先下降后上升的趋势;水分体积分数的增加对几种产物均有促进作用,且对3种含硫产物的促进作用强于对CO2的促进作用。气体产物体积分数比值φ（SOF2＋SO2）/φ（SO2F2）随水分体积分数表现出较好的稳定性,最终稳定在3~4之间;φ（SOF2＋SO2＋SO2F2）/φ（CO2）则随着φ（H2O）的增加呈现总体增长的趋势,低体积分数水分下的值在2.5~3之间。因此,SF6气体分解检测法应用过程中需要充分考虑水分体积分数的影响。

英文摘要：

The normal contact problem of two spheres was studied to investigate the contact regime of curvature joint interface. The force applied to the circular contact region formed by the point higher pair contact of two spheres was analyzed through utilizing the virtual material thickness of joint interface. The Majumdar-Bhushan plane model and classic Hertz theory were combined in the analysis. It was demonstrated that the entire definite range of fractal dimension satisfies 1≤D〈 2 in the two-dimensional Weierstrass-Mandelbrot fractal function by adopting Hardy＇s non-differentiable condition at a point anywhere. Numerical simulation exhibits that the spherical generalized contact area ratio is not greater than one. The spherical generalized contact area ratio in inner contact is larger than that of outer contact. The spherical generalized contact area ratio may increase by increasing the compressive force or reducing the virtual material thickness of joint interface. The true contact area in internal contact is higher than it in external contact. As the fractal roughness, material hardness or virtual material thickness of joint interface increases, the true contact area decreases. As the fraetal roughness increases, the the fact that an increase in the fractal roughness implies an increase in microcontact ＇s normal deformation, which therefore requires a higher compressive force. As the value of fractal dimension increases from 1.4 to 1.5, the actual contact area first increases for a given compressive force. As the value of fractal dimension increases from 1.5 to 1.9, the true contact area decreases. The Hertz stress in internal contact is smaller than that in external contact. These research findings may provide a basis for further research on the contact strength calculation of spherical bearing. The spherical contact fractal model possesses the universality and practicality to expand the mechanical part contact strength theory in machine design.