为适应战场环境的快速变化,要求系统具有高机动性能,也要求用来装载和保护电子设备的携行箱更加轻量化。文中针对轻量化需求,采用高强度、高模量的碳纤维材料和耐冲击性能好的芳纶材料作为增强复合材料,研究真空辅助树脂传递模塑(Vacuum...为适应战场环境的快速变化,要求系统具有高机动性能,也要求用来装载和保护电子设备的携行箱更加轻量化。文中针对轻量化需求,采用高强度、高模量的碳纤维材料和耐冲击性能好的芳纶材料作为增强复合材料,研究真空辅助树脂传递模塑(Vacuum Assisted Resin Transfer Molding,VARTM)整体成型工艺,研制了轻型复合材料携行箱,并对携行箱VARTM工艺成型的有效性及可行性进行了验证。采用该工艺制作的携行箱具有重量轻、强度高、成型快速、生产效率高、制造成本低、环境适应性强等优点,具有较高的工程价值和发展前景。展开更多
在树脂传递模塑(Resin transfer molding,RTM)工艺中,边缘效应很容易导致制件产生空隙、干斑等缺陷,其根本原因是在纤维增强体和模具模腔之间的间隙区域树脂的流动阻力小,使得树脂在这一区域流动速度更快。基于达西定律并结合流体体积(V...在树脂传递模塑(Resin transfer molding,RTM)工艺中,边缘效应很容易导致制件产生空隙、干斑等缺陷,其根本原因是在纤维增强体和模具模腔之间的间隙区域树脂的流动阻力小,使得树脂在这一区域流动速度更快。基于达西定律并结合流体体积(Volume of Fluid,VOF)界面追踪方法建立了树脂在纤维增强体中的流动模型,开展RTM工艺边缘效应的数值模拟研究,模型可以准确模拟边缘效应的影响,同时研究树脂粘度及树脂注射压力等工艺参数对于流动时间的影响。研究结果可以对RTM工艺的改善优化提供帮助。展开更多
The thermal conductivity of epoxy resin can be increased by a factor of eight to ten by loading with highly conductive particles. However, higher loadings increase the viscosity of the resin and hamper its use for liq...The thermal conductivity of epoxy resin can be increased by a factor of eight to ten by loading with highly conductive particles. However, higher loadings increase the viscosity of the resin and hamper its use for liquid composite molding processes. Thus, the enhancement of the out-of-plane thermal conductivity of carbon composites manufactured by VARTM and accomplished by matrix filling is limited to about 250%. In order to derive higher increases in out-of-plane thermal conductivity, additional measures have to be taken. These consist of introducing thermally conductive fibers in out-of-plane direction of the preform using a 3D-weaving process. Measured out-of-plane thermal conductivities of 3D-woven fabric composites are significantly increased compared to a typical laminated composite. It has been shown that if introducing highly conductive z-fibers, the use of a particle filled resin is not necessary and furthermore should be avoided due to the manufacturing problems mentioned above. An existing analytical model was altered to predict the effective thermal conductivity as a function of the composite material properties such as the thermal conductivities and volume contents of fibers in in-plane and out-of-plane directions, the thermal conductivity of the loaded resin, the grid-density of the out- of-plane fibers, and material properties of the contacting material. The predicted results are compared with measured data of manufactured samples.展开更多
文摘为适应战场环境的快速变化,要求系统具有高机动性能,也要求用来装载和保护电子设备的携行箱更加轻量化。文中针对轻量化需求,采用高强度、高模量的碳纤维材料和耐冲击性能好的芳纶材料作为增强复合材料,研究真空辅助树脂传递模塑(Vacuum Assisted Resin Transfer Molding,VARTM)整体成型工艺,研制了轻型复合材料携行箱,并对携行箱VARTM工艺成型的有效性及可行性进行了验证。采用该工艺制作的携行箱具有重量轻、强度高、成型快速、生产效率高、制造成本低、环境适应性强等优点,具有较高的工程价值和发展前景。
文摘在树脂传递模塑(Resin transfer molding,RTM)工艺中,边缘效应很容易导致制件产生空隙、干斑等缺陷,其根本原因是在纤维增强体和模具模腔之间的间隙区域树脂的流动阻力小,使得树脂在这一区域流动速度更快。基于达西定律并结合流体体积(Volume of Fluid,VOF)界面追踪方法建立了树脂在纤维增强体中的流动模型,开展RTM工艺边缘效应的数值模拟研究,模型可以准确模拟边缘效应的影响,同时研究树脂粘度及树脂注射压力等工艺参数对于流动时间的影响。研究结果可以对RTM工艺的改善优化提供帮助。
文摘The thermal conductivity of epoxy resin can be increased by a factor of eight to ten by loading with highly conductive particles. However, higher loadings increase the viscosity of the resin and hamper its use for liquid composite molding processes. Thus, the enhancement of the out-of-plane thermal conductivity of carbon composites manufactured by VARTM and accomplished by matrix filling is limited to about 250%. In order to derive higher increases in out-of-plane thermal conductivity, additional measures have to be taken. These consist of introducing thermally conductive fibers in out-of-plane direction of the preform using a 3D-weaving process. Measured out-of-plane thermal conductivities of 3D-woven fabric composites are significantly increased compared to a typical laminated composite. It has been shown that if introducing highly conductive z-fibers, the use of a particle filled resin is not necessary and furthermore should be avoided due to the manufacturing problems mentioned above. An existing analytical model was altered to predict the effective thermal conductivity as a function of the composite material properties such as the thermal conductivities and volume contents of fibers in in-plane and out-of-plane directions, the thermal conductivity of the loaded resin, the grid-density of the out- of-plane fibers, and material properties of the contacting material. The predicted results are compared with measured data of manufactured samples.
