The pultrusion of the polybenzoxazine resin matrix Z-pin is studied, because the Z-pin technology is an efficient reinforcement method for composites. Based on the curing characteristics acquired by differential scann...The pultrusion of the polybenzoxazine resin matrix Z-pin is studied, because the Z-pin technology is an efficient reinforcement method for composites. Based on the curing characteristics acquired by differential scanning calorimeter（DSC） analysis, the suitable mould temperature for pultrusion is researched with the visual inspection and the Z-pin short beam shear test. The pull-out test is designed to evaluate the post oven temperature that can affect the combination between Z-pins and laminates. And then, the appropriate temperature for the post oven is obtained. Finally, micro photos are used to inspect the defects in Z-pins. The results show that when the resin is heated to 70°C, Z-pin pultrusion demands for viscosity are satisfied, and the shelf-life is about 4 h. With the mould temperature increasing to 140°C, the Z-pin short beam shear strength rises correspondingly and the cross section profile is the best. When the post oven temperature declines, the combination between Z-pins and laminates becomes stronger. However, pores appear in Z-pins unless the oven temperature increases to 200°C. Therefore, the optimum post oven temperature should be set at 200°C.展开更多
针对传统宽波束天线的局限性,提出基于人工电磁结构的宽波束天线设计.该天线采用两层结构设计,底层辐射体通过引入接地短路探针的方式拓宽圆极化3 d B轴比波束;顶层为方环结构的人工电磁结构,利用其波束赋形特性,增大天线半功率波束宽度...针对传统宽波束天线的局限性,提出基于人工电磁结构的宽波束天线设计.该天线采用两层结构设计,底层辐射体通过引入接地短路探针的方式拓宽圆极化3 d B轴比波束;顶层为方环结构的人工电磁结构,利用其波束赋形特性,增大天线半功率波束宽度.基于该方法设计的天线,兼顾宽圆极化3 dB轴比波束和半功率波束特性,能够应用于北斗卫星导航系统用户终端.展开更多
基金Supported by the Military Product Itemthe Research Funding of Nanjing University of Aeronautics and Astronautics(NS2010162)~~
文摘The pultrusion of the polybenzoxazine resin matrix Z-pin is studied, because the Z-pin technology is an efficient reinforcement method for composites. Based on the curing characteristics acquired by differential scanning calorimeter（DSC） analysis, the suitable mould temperature for pultrusion is researched with the visual inspection and the Z-pin short beam shear test. The pull-out test is designed to evaluate the post oven temperature that can affect the combination between Z-pins and laminates. And then, the appropriate temperature for the post oven is obtained. Finally, micro photos are used to inspect the defects in Z-pins. The results show that when the resin is heated to 70°C, Z-pin pultrusion demands for viscosity are satisfied, and the shelf-life is about 4 h. With the mould temperature increasing to 140°C, the Z-pin short beam shear strength rises correspondingly and the cross section profile is the best. When the post oven temperature declines, the combination between Z-pins and laminates becomes stronger. However, pores appear in Z-pins unless the oven temperature increases to 200°C. Therefore, the optimum post oven temperature should be set at 200°C.
文摘针对传统宽波束天线的局限性,提出基于人工电磁结构的宽波束天线设计.该天线采用两层结构设计,底层辐射体通过引入接地短路探针的方式拓宽圆极化3 d B轴比波束;顶层为方环结构的人工电磁结构,利用其波束赋形特性,增大天线半功率波束宽度.基于该方法设计的天线,兼顾宽圆极化3 dB轴比波束和半功率波束特性,能够应用于北斗卫星导航系统用户终端.
