Interfacial Properties Modification of Carbon Fiber/ Polyarylacetylene Composites

This work was dedicated to performing surface oxidation and coating treatments on carbon fibers (CF) and investigating the changes of fiber surface properties after these treatments, including surface composition, relative volume of functional groups, and sur- face topography with X-ray photoelectron spectroscopy (XPS) and atom force microscopy (AFM) technology. The results show that, after oxidation treatments, interfacial properties between CF and non-polar polyarylacetylene (PAA) resin are remarkably modified by removing weak surface layers and increasing fiber surface roughness. Coating treatment by high char phenolic resin solution after oxida- tion makes interface of CF/PAA composites to be upgraded and the interfacial properties further bettered.     

Thermal Stresses and Cracks During the Growth of Large-sized Sapphire with SAPMAC Method

本文利用有限元法对冷心放肩微量提拉法(SAPMAC)生长大尺寸蓝宝石单晶过程中的热应力进行了模拟计算,应用临界缺陷理论解释了裂纹的萌生与扩展机理。研究表明,晶体内的热应力主要与晶体生长速率,环境温度和结晶取向有关;较大热应力多出现在结晶界面,放肩、收尾以及直径急剧变化等位置;最大热应力总是出现在籽晶与新生晶体的界面附近。裂纹将在临界缺陷位置产生,并在应力作用下沿a或m面扩展。计算结果与实验结果基本吻合,通过晶体生长系统和生长工艺的改进,对晶体的开裂问题得到了有效的抑制。     

陶瓷基复合材料单纤维拔出力学分析

建立了考虑界面滑动摩擦的复合材料单纤维拔出力学模型,得到了包含泊松效应影响的基体轴向应力、纤维轴向应力和界面剪切应力的表达式.针对SiC/RBSN陶瓷基复合材料,在部分脱粘/滑移和完全粘结情况下,对纤维、基体、界面的应力分布进行了分析.计算结果与有限元计算结果相比,具有较好的一致性.结果表明:纤维百分含量的变化能够改变界面发生脱粘/滑移失效点的位置;界面发生脱粘/滑移后的脱粘扩展比界面完全粘结的脱粘扩展更容易发生;不考虑热不匹配的影响,仅通过增加界面摩擦系数不能使应力重分布发生很大变化.      

固体发动机界面结构试件脱粘健康监测研究

以复合材料壳体和绝热层脱粘模型试件为对象,利用粘贴于壳体外表面的压电主动激励传感器,基于高频机电阻抗方法,对模拟药柱/绝热层界面脱粘的结构健康状态监测进行了数值仿真和实验研究,得出了不同脱粘损伤工况下的导纳频谱曲线,计算了能表征脱粘程度的平均绝对偏差损伤指标。结果表明,高频机电阻抗方法可利用粘贴于壳体外表面的压电传感器有效地识别内部结构的界面脱粘,相比于传统检测方法,能实现实时的结构健康监测,损伤指标能量化表征脱粘程度,实验采用的两种压电传感器中,MFC传感器较PZT传感器更适合于曲面固体发动机壳体脱粘检测,为开展实际工况下的固体发动机药柱结构界面脱粘损伤监检测工作提供理论与技术支撑。     

硅微谐振加速度计的研究现状及发展趋势

硅微谐振加速度计具有体积小、 功耗低、 准数字量输出和精度提升大的优点,是一种具有良好应用前景的高精度MEMS惯性仪表.总结分析了近些年国内外在硅微谐振加速度计方面的研究现状,主要在结构设计及工艺、 测控电路设计等方面阐述了各自特点.最后,结合近些年MEMS惯性仪表的发展趋势,对硅微谐振加速度计晶圆级真空封装、 测控电路数字化、仪表补偿智能化3个发展方向进行了展望.     

Multiscale Modelling of Aerospace Composites——A Perspective

This paper introduces a series of approaches in the modelling of composites with complex multiscale structures and features. Fundamental theory underlying multiscale structures are brought to light and discussed. There can be considerable benefit in the representative application of multiscale modelling techniques to civil aircraft design and this aim of this paper is to provide essential perspectives from several fields of research that may be beneficial to aerospace composites modelling methodologies if applied appropriately.     

Investigation of MHD power generation with supersonic non-equilibrium RF discharge

Magnetohydrodynamic (MHD) power generation with supersonic non-equilibrium plasma is demonstrated. Capacitively coupled radio frequency (RF) discharge (6 MHz, maximum continual power output of 200 W) was adopted to ionize the Mach number 3.5 (650 m/s), 0.023 kg/m3 airflow. In a MHD channel of 16 mm × 10 mm × 20 mm, MHD open voltage of 10 V is realized in the magnetic field of 1.25 T, and power of 0.12 mW is extracted steadily and con-tinuously in the magnetic field of 1 T. The reasons for limited power generation are proposed as:low conductivity of RF discharge; large touch resistance between MHD electrode and plasma;strong current eddies due to flow boundary layer. In addition, the cathode voltage fall is too low to have obvious effects on MHD power generation.     

压力传感器单电源调理电路技术研究

对单电源供电的压力传感器调试中出现零位输出较大且存在相应死区的问题,进行了理论分析,找出了问题原因,采取了有效的解决措施,为传感器产品化和产业化奠定了基础。     

多植保无人机协同路径规划

为实现多植保无人机（UAVs）协同作业,并提高作业效率,提出了一种基于改进粒子群优化（PSO）的多植保无人机协同路径规划算法。根据作业区域的形状面积和植保UAV的作业参数划分各架UAV作业区域,采用栅格法生成各区域全覆盖作业航线。以各架植保UAV各架次植保作业距离为算法寻优变量,在确保各架UAV补给时间满足间隔分布约束条件下,综合考虑补给总次数、返航补给总时间、总耗时和最小补给时间间隔4项因素,并构成目标函数,通过采用改进PSO算法,实现了对各UAV返航顺序和返航点位置的寻优。仿真分析结果表明,相较于最大作业距离规划和最小返航距离规划,本文提出的规划算法表现出了较优的性能和较好的作业区域适应性,证实了其有效性和实用性。     

多通道加载系统上位机软件设计

基于加载系统的工作原理和试验需求,实现了对多通道加载系统上位机软件的功能设计;在软件开发过程中利用多线程机制及LabWindows/CVI中TCP支持库实现了实时数据处理和通讯接口要求。试验证明,该上位机软件在某型飞机地面模拟试验系统中运行良好,提供了试验配置和数据处理功能,满足了实时性、可靠性要求。