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《中国航空学报》2019,32(9):2211-2221
Carbon fiber reinforced plastic and titanium alloy (CFRP/Ti) stacks have been widely used as aerospace structures because of their excellent combination of physical properties. Interface damage caused by interface gaps, significantly different from that of metal/metal stacks, is a common problem in the through-hole drilling of CFRP/Ti stacks with low stiffness. In this study, a force–deformation coupling model was developed to further examine the formation mechanism and the control method of interface damage. Firstly, the coupling model was built considering the interaction between the thrust force and the deformation. To solve this model, a numerical method was proposed in which specific cutting coefficients were calibrated using only the thrust force of rigid stacks. Secondly, drilling experiments were performed with different feed rates and bending stiffness. Experimental results indicate that interface damage mainly includes interlayer chips and surface damage of CFRP layers. The surface damage, which is irreparable, is caused by the rotary extension of metal chips along the interlayer gap. Thirdly, variations of the interface gap were calculated with the coupling model that had been verified by measured thrust forces. The damage area was found to have a linear dependence relation with the interlayer gap. However, in conditions of large gap sizes, the interface damage areas increased with the interlayer gap at high feed rates, while decreasing slightly at low feed rates. This phenomenon was satisfactorily explained by the presented model. Finally, a method was proposed to determine the appropriate pressure exceeding which no interlayer damage will occur. Additional drilling experiments proved the method effective. This study leads to further understanding of the forming mechanism of interlayer damage and of selecting appropriate parameters in drilling low-stiffness composite/metal stacks. 相似文献
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Interconnected Ni(OH)2 nanoflakes and polyether amine(PEA) were deposited on carbon fiber tows via a facial and effective process of chemical bath deposition and dip coating. Based on this, a win–win benefit of simultaneously improvements in interfacial shear strength(IFSS) of carbon fiber/epoxy composites and the electrochemical activity has been achieved. Compared with CF and CF-Ni(OH)2 composites, the IFSS of CF-Ni(OH)2-PEA/epoxy composite respectively increas... 相似文献
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描述了机载固态数据存储器与地面测试计算机通信接口的硬件设计和相应的软件设计,根据不同的应用要求,采用不同的设计方法,其中包括近距离直接RS232串行通信、长距离电流驱动RS232串口通信和RS485异步通信。介绍了采用MAXIM公司的MAX232和MAX485实现各种通信接口的设计方法。 相似文献
25.
将扩展有限元法(XFEM)用于研究固体火箭发动机(SRM)壳体/绝热层的脱粘。将层隙型和紧贴型脱粘等效为双材料界面裂纹,建立了XFEM的双材料界面裂纹分析模型,并给出了其中核心算法——应变矩阵的求解,通过相互作用积分求出应力强度因子和能量释放率。算例结果表明,XFEM的计算结果与理论值的差异较小,可用于有效求解脱粘问题。 相似文献
26.
利用Visual Basic串口通信技术使单片机与计算机相连接,并且在visual Basic环境下编写数字采集虚拟频率测试系统的程序,实现对数字量信号多种参数的采集、传送、实时测量及显示(频率、周期、脉冲宽度,占空比以及TTL电平采集等)。结果表明,设计具有较准确的测量能力和广泛的实用性,系统成功实现了局域网络远程测量,界面友好。 相似文献
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LIU Hua YANG Jia-ling LIU Kai-xin 《中国航空学报》2007,20(3):210-214
Theoretical analysis and numerical calculations of Love wave propagation in layered graded composites with imperfectly bonded interface are described in this paper. On the basis of WKB method, the approximate analytic solutions for Love waves are obtained. By the interface shear spring model, the dispersion relations for Love waves in layered graded composite structures with rigid, slip, and imperfectly bonded interfaces are given, and the effects of the interface conditions on the phase velocities of Love waves in SiC/Al lay- ered graded composites are discussed. Numerical analysis shows that the phase velocity decreases when the defined flexibility parameter is greater. For the general imperfectly bonded interface, the phase velocity changes in the range of the velocities for the rigid and slip interface conditions. 相似文献
28.
操作系统厂商经常在ISO标准字符集之外添加一些特殊的字符,这些特殊字符不能为Java所识别,从而出现乱码。介绍了通过J2SE中Service Provider Interface编程接口实现自定义字符集编解码器,对特殊字符进行解码,来解决乱码问题的方法,并通过代码演示了实现字符集编解码器的步骤和所要考虑的问题。通过文中所描述的方法,可以无缝的将用户自定义字符集编解码器集成到Java运行环境中。 相似文献
29.
文章首先将载人航天中产生人失误的原因分为三大类型:载人航天器系统人机界面本身设计不当、生产加工与装配错误以及由人自身的局限性所引发的操作错误。在此基础上,详细论述了为防止航天员发生失误而采取的研究对策。最后,提出几点建议以供讨论。 相似文献
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