雷达罩无损检测技术研究

雷达罩无损检测技术研究北京航空材料研究院马震亚，莫安来，苏飞，汪松，刘永斌，康利红机载雷达罩是由树脂基玻璃纤维增强层板和Ｎｏｍｅｘ蜂窝芯胶接热压成型法制成。由于用材多样、诸材料间性能差异大以及制作工艺中人为因素较多，为无损检测带来了极大困难。制件组织...     

航空蜂窝芯材自动浸胶机

由中国航空工业第一集团公司北京航空材料研究院和广东中山科力高自动化设备有限公司联合研制的全自动蜂窝浸胶机,现已完成全面工艺试验和试生产。因芳纶蜂窝具备一系列优良特性,故在航空航天和众多工业领域得到了越来越广泛的应用。目前国产飞机中就有十多种型号大量采用了芳纶蜂窝。但影响蜂窝外观、性能和生产效率的关键工艺浸胶,     

Nomex蜂窝在俄罗斯航空领域的发展及应用

本文对Ｎｏｍｅｘ蜂窝在俄罗斯航空领域的发展与应用进行了评述，并介绍了其研制水平及工艺特点。     

会议动态

无孔蜂窝用胶选胶会议 三机部技术局根据新机设计定型的需要,于1979年12月21至25日在沈阳召开了无孔蜂窝用胶的选胶会议。会议听取了会战单位的工作报告,根据新机对无孔蜂窝用胶的技术要求,进行了认真讨论,一致认为:自力-4胶在完成试验室阶段的研制工作后,经会战组联合进行复验与工艺试验表明,性能基本满足设计要求,工艺性好,可不浸胶瘤,不涂底胶;流动性适中,挥发物含量低;性能稳定;原材料来源方便,可选作新机无孔蜂窝结构用胶,进入使用试验阶段,并安排了二架份副翼和1:1平尾试验件的生产和试验工作。     

温度对Nomex蜂窝压缩和剪切强度影响

本文着重讨论了Ｎｏｍｅｘ蜂窝的压缩强度和剪切强度与温度的关系。研究表明，随着温度升高，压缩强度和剪切强度均下降，但趋势不同，压缩强度开始下降较快，以后下降缓慢，而剪切强度总的下降趋势较缓慢。     

酚醛型纸蜂窝浸渍胶的实验研究

本文对酚醛型纸蜂窝浸渍胶进行了研究。即采用聚乙烯醇缩和增韧剂，配制了六种配比的胶液，并对浸渍该上胶液的纸蜂窝的平压等性能进行了测试和分析，给出了综合性能好和较好的配比。     

酚醛型纸蜂窝浸渍胶的实验研究

本文对酚醛型纸蜂窝浸渍胶进行了研究，即采用聚乙烯醇缩丁醛作增韧剂，配制了六种配比的胶液，并对浸渍该六种胶液的纸蜂窝的平压、剪切、吸湿等性能进行了测试和分析，给出了综合性能好和较好的配比。     

蜂窝夹芯芳纶前缘固化工艺技术

该文以某型飞机蜂窝夹芯芳纶前缘为研究对象,对芳纶预浸料的特点和零件成型制造的难点进行分析,并且开展了一系列成型方案攻关研究。经多个制件验证,采用共胶接成型方法并选用0.4MPa作为共胶接压力的固化工艺方案合理可行,制件完全满足相关技术和质量要求,实现了蜂窝夹芯芳纶前缘的批量化稳定生产,该研究结果为芳纶预浸料类似结构制件的制造提供了借鉴。     

蜂窝夹层结构吸波材料研究

本文对影响蜂窝吸波性能的一些因素,如浸渍胶液体系、蜂窝孔格尺寸、蜂窝高度、浸渍工艺等进行了研究,总结出了一定规律,为今后进一步深入研究打下了基础。     

芳纶纸蜂窝力学性能与纸张性能相关性的研究

研究了芳纶纸蜂窝压缩模量E和剪切模量G与孔壁材料性能的相关性,并验证了Kelsey等提出的蜂窝压缩和剪切力学模型。结果表明,蜂窝孔壁材料的弹性模量与厚度的乘积Est是影响蜂窝平压模量的关键性能参数,Est值随着酚醛树脂上胶量的增加而增大,E也随着酚醛树脂上胶量的增加而增大;蜂窝孔壁材料剪切模量与厚度的乘积Gst是影响蜂窝剪切模量G的关键性能参数,Gst值随着酚醛树脂上胶量的增加而增大,G也随着酚醛树脂上胶量的增加而增大。     

Mechanical properties of Nomex material and Nomex honeycomb structure

This paper presents extensive test results of linear elastic mechanical properties of Nomex paper and Nomex honeycomb structures. The fundamental mechanical properties of the Nomex paper are then used in the finite element modeling and analysis of Nomex honeycomb structures. The finite element results are then compared with the experimental results and with the results using the well known theory from Gibson and Ashby [Gibson LJ, Ashby MF. Cellular solids: structures & properties. Pergamon Press; 1988]. Size effects are observed for the moduli of Nomex honeycombs.     

基于ANSYS11.0的蜂窝纸芯静压特性研究

通过对蜂窝纸压缩破坏过程的分析,建立蜂窝纸芯压缩力学模型及临界载荷的计算方法。利用AN-SYS11.0对不同边长的Nomex蜂窝芯的压缩进行了模拟,得到了不同位移载荷下芯纸的变形特点及应力分布图。结果表明,蜂窝纸的结构参数(特别是纸芯边长)对蜂窝纸芯的承载能力有很大的影响。     

自黏附型酚醛树脂流变特性及其预浸料与Nomex蜂窝芯共固化黏接性能

采用流变仪研究了固化反应温度、时间以及增韧剂和增稠剂加入量对酚醛树脂流变特性的影响,并测试了玻璃纤维增强酚醛预浸料与Nomex蜂窝芯共固化成型后玻璃纤维/酚醛-Nomex蜂窝夹层结构复合材料的板-芯黏接性能。结果表明:改性后酚醛树脂在高温时的黏度提高较多,流动性得到了有效改善,所得预浸料与Nomex蜂窝芯的界面黏接明显增强,并且当增韧剂和增稠剂的加入量与纯酚醛树脂的质量比分别为5%和3%时,所制备出的夹层板的滚筒剥离强度达到15 N·mm/mm以上,改性后酚醛树脂及其预浸料具有了一定程度的自黏附特性。此外,在共固化工艺中采用合适的升温制度,可以进一步提高玻璃纤维/酚醛-Nomex蜂窝夹层结构复合材料的板-芯黏接强度。      

Scaling of honeycomb compressive yield stresses

In this study, the compressive yield stresses of phenolic-dipped Nomex^® rings were scaled and correlated to honeycomb core. A honeycomb-scaling factor and geometric end constraint factor were found to relate the rings and core through the relative yield stresses and their physical dimensions and properties of the honeycomb materials. The compressive properties of the Nomex rings were also investigated using both a model and a commercial phenolic honeycomb dip resin. The Nomex rings manufactured from the model resin were found to have higher compressive properties. These properties were attributed to the higher fracture toughness of the resin, and both resins were found to accurately scale from rings to core with the honeycomb-scaling factor. Ultimately, this research can be used to innovate and efficiently characterize the compressive properties of different honeycomb webs and dip resins without having to make the significant investment of time and resources associated with large scale honeycomb testing.     

Processing for Sandwich Composite Based on Natural Fiber Facesheet and Nomex Honeycomb Core

The sandwich composite based on ramie fiber facesheet and Nomex honeycomb core was produced.The thermal properties of resin and fiber were measured by the differential scanning calorimetry (DSC),Thermogravimetrie analysis (TGA) and melt viscosity spectrometer.Influence of vacuum bag process and autoclave process on large curvature deformation capability and flatwise tension strengths of sandwich composites were studied.The results showed that honeycomb core of 48kg/m3 had very good deformation capability and the flatwise tension strength of sandwich composite by autoclave process is 1.07MPa vs 0.76MPa by vacuum bag process.     

羧基丁腈橡胶的制备及在耐温环氧胶中的应用

采用接枝的方法在丁腈-40分子链中接入羧基,获得了高门尼黏度的羧基丁腈橡胶,并用其对环氧树脂进行改性,从而制备出耐高温环氧树脂结构胶。通过加入促进剂可将固化温度从180℃降至120℃。     

Nomex蜂窝夹层结构真空袋共固化过程蜂窝变形

针对蜂窝夹层板的共固化工艺,以玻璃纤维120斜纹织物/环氧5224体系为面板,以Nomex蜂窝为夹芯材料,研究了蜂窝侧向抗压刚度的影响因素,并通过自行建立的成型过程气压测试装置,分析了芯材内压的影响因素及蜂窝的变形情况。结果表明：对于孔格边长和芯材高度较大的情况,蜂窝侧向抗压能力较小,在真空压力的作用下容易发生变形;芯材内压与芯材内气体的膨胀和预浸料铺层的渗透性直接相关,因此芯材内压受温度制度、预浸料层数和胶膜影响较大;芯材内压对抵抗蜂窝变形起到重要作用,预浸料凝胶前较大的芯材内压有利于抑制蜂窝变形的发生。     

Testing and modeling of Nomex™ honeycomb sandwich Panels with bolt insert

Nomex™ honeycomb core sandwich panels with a bolt insert were load tested and modeled. The objective was to predict the honeycomb local buckling load and to identify a Nomex™ honeycomb constituent material model. Sandwich specimens were subjected to bolt pull-out load tests. The same sandwich structure was also tested in flat-wise tension with strain gages installed on the honeycomb walls. Finite element models of the flat-wise tension and bolt pull-out tests were built. The honeycomb geometry and strain gages were modeled with shell elements. An orthotropic honeycomb material model was identified by comparing the two test models to the experimental data. The material parameters identified are in the mid-range of previously published values. The pull-out test model was used to predict honeycomb wall buckling with a nodal rotation vector sum criterion. The buckling loads predictions closely corresponded to the start of the experimental load/displacement slope transition zone.     

The sensitivity of an NDT instrument based on the membrane resonance method

The sensitivity of a commercial instrument based on the membrane resonance method of nondestructive testing has been investigated. Tests have been carried out on aluminium plates with flat-bottomed holes and on structures with CFRP skins having aluminium and Nomex honeycomb cores with deliberately introduced skin-core disbonds. The results indicate that on conducting structures, using eddy current excitation, the instrument has greater sensitivity to deep defects than either the mechanical impedance or coin-tap methods, 50 mm diameter defects 7 mm deep being detectable in an aluminium structure, whereas with the other techniques, the margin of detectability is at depths between 3 and 5 mm. The results indicate that the sensitivity of the method to near-surface defects is comparable to that of the coin-tap technique, and that like the coin-tap method its reliability is maintained on flexible structures whereas that of the mechanical impedance method is severely reduced. The eddy current excitation system used in the tests reported here cannot be used on weakly conducting materials such as CFRP-skinned Nomex honeycomb. If an alternative piezoelectric exciter were to be used, the advantages of a non-contacting system would be lost.     

复合材料夹芯板低速冲击后弯曲及横向静压特性

对低速冲击后的复合材料Nomex 蜂窝夹芯板进行了纯弯曲和准静态横向压缩实验, 用X 光技术、热揭层技术和外观检测等对板内的损伤进行测量, 分析了被冲击面在受压情况下蜂窝夹芯板的弯曲破坏特点, 对比了横向静压与低速冲击所造成的板内损伤, 讨论了不同横向压缩速度时接触力P-压入位移$h 的变化规律和损伤情况。结果表明: 低速冲击可使蜂窝夹芯板的弯曲强度大幅度降低; Nomex 蜂窝夹芯板对低速冲击不敏感。