树脂基复合材料缺陷表征与评价方法研究综述

复合材料结构中的制造缺陷严重影响航天装备的服役性能,如何实现复合材料缺陷的高精度检测表征与评价对航天装备的安全性设计意义重大。针对树脂基复合材料缺陷的先进表征技术及评价方法进行概述,重点介绍了复合材料成型工艺与典型缺陷类型、常用复合材料缺陷检测与原位表征技术和复合材料缺陷分析评价方法。通过对复合材料缺陷研究现状的梳理,可见计算机断层扫描技术和基于图像的数值计算方法正以其独特的精确度优势在复合材料缺陷的表征与分析领域崭露头角。同时还对先进的复合材料检测与评价技术在航天装备中复合材料结构安全性设计与可靠性分析方面的应用和发展趋势进行了展望。     

Low-velocity impact response and infrared radiation characteristics of thermoplastic/thermoset composites

The low-velocity impact response and infrared radiation characteristics of composites have rarely been focused on simultaneously. This study aims to investigate the low-velocity impact response and infrared radiation characteristics of the glass fiber reinforced thermoplastic polypropylene and carbon fiber reinforced thermosetting epoxy resin laminates wildly used in the aircraft industry. The impact tests were conducted at five energy levels. Characterization parameters such as impact load, dis...     

热压罐成型变厚度层板缺陷研究

以S-2玻璃纤维／环氧648变厚度层板为研究对象，采用热压罐工艺成型，考察了不同铺层方式和阶梯宽度下缺陷的形成情况。研究结果表明，由于厚度梯度的存在，层板中容易产生纤维分布不均、富树脂、孔隙和分层缺陷，这与树脂的二维流动、纤维的滑移和结构的不对称性有关，铺层方式对各种缺陷影响显著。变厚度层板成型过程中倾角减小使得尺寸难以预测和控制，成型过程中应尽量避免树脂的流动。     

三维表面形貌的功能评定方法

三维表面形貌受生成机理的影响 ,与表面功能密切相关 ,对表面的功能评定至关重要。论述了三维表面功能评定的各种方法 ,如最小二乘多项式拟合、滤波、Motif法和分形方法 ,并分析归纳了存在的问题和发展趋势。     

复杂电磁环境表征方法

复杂电磁环境表征是电子信息系统复杂电磁环境效应研究的基础性问题之一.基于电磁环境的复杂性特点,提出了一种复杂电磁环境表征方法,该方法从实体环境、电磁信号环境和基于特定电子信息装备的电磁信号环境等三个方面进行参数化描述,为复杂电磁环境认知和模拟奠定基础.     

Reduction of satellite electromagnetic scattering by carbon nanostructured multilayers

We propose a low observable satellite covered by layered materials. The dielectric properties of the composite materials are analyzed using the coaxial air-line method. Our solution could result in cost-effective applications for satellite stealthness. The particle swarm optimization algorithm is used to design and optimize layered absorbers. The obtained reflection is below −20 dB in many frequency subranges, also under an oblique incident condition, within the band 2–18 GHz. The optimized layered absorbers are used as a cloak for cube satellites. In particular, we investigated a very simple geometry by using a finite element commercial software in the band from 2 to 18. Finally, the transmission through an aperture on the satellite surface is analyzed. It is highlighted that the optimized layered absorbers attenuate the electric field within the satellite, improving its immunity against electromagnetic interferences.     

双级轴向涡流器文氏管长度对流场和喷雾特性影响

为了研究双级轴向涡流器文氏管长度对流场和喷雾特性的影响,通过数值计算和试验分别研究了4种文氏管长度的双级轴向涡流器方案的下游流场和匹配喷嘴的雾化特性。结果表明:随着文氏管无量纲长度由0.23增加至0.49,一级涡流器流量系数由0.98降至0.7,二级涡流器的流量系数保持0.75不变,涡流器出口旋流数由0.08增至0.48,旋流扩张角由闭合状态增至约90°,涡流器下游流场由反转回流区变为传统回流区。文氏管长度最短的方案的索太尔平均直径(SMD)和喷雾锥角受涡流器压降的影响较小,而其他方案的SMD和喷雾锥角受涡流器压降影响较大,且在相同涡流器压降和油压下,SMD和喷雾锥角随着文氏管长度增加而增大。      

A review of numerical analyses and experimental characterization methods for forming of textile reinforcements

The forming of textile reinforcements is an important stage in the manufacturing of textile composite parts with Liquid Composite Molding process. Fiber orientations and part geometry obtained from this stage have significant impact on the subsequent resin injection and final mechanical properties of composite part. Numerical simulation of textile reinforcement forming is in strong demand as it can greatly reduce the time and cost in the determination of the optimized processing parameters, which is the foundation of the low-cost application of composite materials. This review presents the state of the art of forming modeling methods for textile reinforcement and the corresponding experimental characterization methods developed in this field. The microscopic, mesoscopic and macroscopic models are discussed. Studies concerning the simulation of wrinkling are also presented since it is the most common defect occurred in the textile reinforcement forming. Finally, challenges and recommendations on the future research directions for textile reinforcement modeling and experimental characterization are provided.     

马氏体Cr钢亚晶结构的定量表征

利用透射电镜（TEM）对不同蠕变态的马氏体Cr钢亚晶结构进行了定量表征,得到了不同蠕变态的亚晶尺寸分布曲线,分析了蠕变过程中亚晶结构的变化特征,以及这些变化对显微硬度的影响。结果表明：高应力蠕变,亚晶粗化较小,而低应力蠕变,亚晶粗化显著;蠕变态的亚晶尺寸与硬度之间满足Hall-Petch关系,亚晶粗化引起硬度下降。     

乳液聚合法制备纳米Al2O3/PS核壳式复合粒子

针对纳米粒子易团聚的特点,本文采用乳液聚合方法制备纳米Al2O3／PS复合粒子来进行改性,考察了不同工艺参数对乳液聚合的影响,并运用TEM、FTIR对复合粒子进行了表征。研究发现：在反应温度为800℃,乳化剂为$DS和OP—10复合乳化剂,St和纳米Al2O3投料比为2：1,单体滴加速度为5滴／min条件下所制备出的复合粒子具有以纳米驰03为核,PS为壳的核壳式结构,其包覆层厚度大约为10～20nm。