炭纤维复合材料疲劳行为的研究进展

炭纤维复合材料在航空航天等领域得到了越来越广泛的应用,但服役过程中的疲劳载荷对其安全性能造成了极大威胁。综述了炭纤维复合材料疲劳损伤机理和抗疲劳处理方面的研究进展,并对炭纤维复合材料疲劳行为的研究趋势做了分析。     

高性能复合材料弯曲疲劳性能研究

用湿法缠绕技术制作了CF／5228预浸料,对热压罐固化的CF／5228复合材料的力学性能和弯曲疲劳性能进行了研究,并用扫描电镜、电子显微镜等对复合材料的疲劳损伤机理进行了微观表征和理论探讨。研究表明,M40J／5228复合材料比M40／5228具有更为优异的耐疲劳性能。复合材料的疲劳损伤主要有纤维断裂、基体开裂和界面剪切破坏3种表现形式,通常复合材料构件的疲劳破坏多为3种形式的综合表现。基体增韧、选用高强高模碳纤维、界面强化和铺层优化是提高复合材料构件耐疲劳性能有效手段。     

复合材料层合板分层疲劳性能研究进展

介绍了近年来复合材料层合板分层疲劳模型、数值模拟、以及I型Ⅱ型和混合型分层疲劳性能试验的研究进展,并对复合材料层合板分层疲劳性能进一步的研究进行了展望。     

氧化石墨烯对炭黑/天然橡胶复合材料耐疲劳性能的影响

研究氧化石墨烯(GO)对炭黑/天然橡胶复合材料性能的影响。结果表明:加入少量GO,可以明显增强复合材料的填料网络结构,提高物理性能和高撕裂能下的耐疲劳性能;对于经历不同疲劳程度后的复合材料,在疲劳前期GO的加入促进了填料的分散,从而减小复合材料的裂纹扩展速率,提高耐疲劳性能。     

碳玻混杂纤维增强复合材料的拉-拉疲劳性能的研究

纤维混杂是一种实现纤维增强树脂基复合材料性能与价格平衡的有效策略,碳/玻混杂织物(GCHF)是典型的纤维混杂实例。复合材料的疲劳性能是工程化应用的必要考核指标。本文以风力发电叶片梁帽用复合材料为研究对象,制备了4种不同混杂比例的单向GCHF增强环氧树脂基复合材料,基于对其静态拉伸性能的研究,扩展到动态拉-拉疲劳(R=0.1)性能,并与纯玻纤和纯碳纤增强环氧树脂基复合材料作对比。实验数据表明,高周疲劳下,GCHF增强环氧树脂基复合材料的疲劳性能符合线性混合定律,但是低周疲劳下误差相对较大。为叶片设计选材提供了一种简便快速估算GCHF增强环氧树脂基复合材料疲劳性能的方法。     

铝合金内衬复合材料高压容器界面粘结的研究

复合材料高压容器由于其质量轻近年来被广泛应用在航天方面,但是复合材料气密性差,通常用金属内衬来提高其气密性.由于铝合金和复合材料变形不协调,致使铝合金内衬耐疲劳性能很差.界面良好的粘接使铝合金和复合材料形变相协调,能够很好的提高铝合金内衬复合材料高压容器的耐疲劳性能.因此,对复合材料和铝合金界面粘结的研究具有重要的意义.     

预固化温度对风电叶片复合材料性能的影响

设计了四种预固化制度对风电叶片用树脂静力性能和单向织物的复合材料疲劳性能进行了研究,研究结果表明预固化温度对环氧树脂基体和复合材料的静力学性能影响不显著,但对复合材料的疲劳性能具有较大的影响,通过实验测试验证了预固化温度对疲劳性能m值的影响趋势,结合叶片制造不同预固化温度对复合材料叶片制造出现的泛白现象进行了分析,明确了玻纤增强树脂基复合材料的制造固化过程的温度边界。     

石墨烯用量对天然橡胶/反式聚异戊二烯复合材料性能的影响

以石墨烯代替部分炭黑制备了天然橡胶(NR)/反式聚异戊二烯(TPI)复合材料,研究了石墨烯用量对NR/TPI复合材料硫化特性、微观结构、力学性能、耐老化性能、耐伸张疲劳性能、耐磨性能及动态力学性能的影响。结果表明,加入石墨烯降低了NR/TPI复合材料的交联密度、邵尔A硬度和耐老化性能;3份石墨烯提高了材料的拉伸强度和撕裂强度;加入3份或5份石墨烯均可在改善材料的耐伸张疲劳性能、耐磨性能和抗湿滑性能的同时,降低其滚动阻力;3份石墨烯在改善材料的抗湿滑性能方面效果更明显,5份石墨烯在降低材料的滚动阻力方面效果更明显。     

改性淀粉/炭黑/丁苯橡胶复合材料的耐疲劳性能研究

采用硅烷偶联剂KH-550对淀粉进行改性,制备改性淀粉/炭黑/丁苯橡胶复合材料,并对其耐疲劳性能进行研究.结果表明:与未加改性剂的胶科相比,加入改性剂的混炼胶焦烧时间和正硫化时间缩短,转矩变化不大,硫化胶综合物理性能较好;当改性剂用量为1份时,复合材料的耐疲劳性能最好;复合材料的耐疲劳性能与其300％定伸应力、抗切割性能及应力松弛相关.     

玻-碳纤维复合材料气瓶疲劳性能研究及优化分析

混杂纤维复合材料具有单一增强纤维复合材料不具备的优异性能。以100 L的CNG-2型气瓶为例,将纤维混杂法技术应用于复合材料气瓶,并采用有限元法对玻-碳纤维复合材料气瓶疲劳性能进行研究及优化。结果表明:在当量厚度比一定的基础上,能使复合材料气瓶疲劳性能和纤维利用率得到提高的最佳混杂比为2∶5,提高其爆破压力的最佳混杂比为5∶8;通过优化,气瓶复合材料层的体积减少了30.3%,质量减少了36.3%。     

氢气纯度分析方法准确性的探讨

ONACCURACYOFANALYSISOFOFHYDROGEN1前言我公司目前应用的氢气纯度分析方法有两种,一种是爆炸反应法,另一种是焦性没食子酸吸收法。几年来,人们对两种分析方法的准确性曾有过褒贬不一的评论。这里我们也谈谈自己粗浅的观点。2爆炸法测定氢气纯度一定量的氢气样品与适量的空气之均匀混合物因反应后生成液体水而引起气体体积减少,减少的体积等于参加反应气体体积之和。其中l／3为氧气,2／3为氢气。根据氢气取样量和反应前后混气体体积之差,以及氢气在反应中的体积比例关系,可计算出样品的氢气纯度。计算公式式中：A一混…     

COMPARISON OF METHODS OF ANALYSIS OF GYPSUM1

The different analytical methods proposed for the evaluation of gypsum have been subjected to an experimental test. A combination method, consisting of a fusion with KHCO₃ and determination of CaO by KMnO₄ titration, the SO₃ by Andrews method of titration of BaCrO₄ has been found to give very reliable results with the least consumption of time.     

SEDIMENTATION OF BINARY MIXTURES OF PARTICLES OF UNEQUAL DENSITIES AND OF DIFFERENT SIZES

A model is developed for the sedimentation from a suspension of two particle species of unequal densities and of different sizes. The composition and the thickness of various layers in the sediments are predicted using graphical and analytical methods. The model predictions were in excellent agreement with experimental results, when the particle size ratio was ≥ 108. When size ratio of the particles was 2.60 and 4.31 the agreement occurred in about 50 percent of the cases.     

HEASUREHENT OF INSTANTANEOUS RATES OF LOSS OF VOIATILE COMPOUNDS DURING DRYING OF DROPS

A novel technique serves to monitor instantaneous rates of loss of a volatile solute from a suspended drop during drying. A highly sensitive electron capture detector is used to monitor concentrations of SF6 released into a flowing gas stream from a suspended, drying drop. Simultaneously, the appearance and morphological development of the drop are monitored with a video camera. This provides the wherewithal of relating instantaneous rates of loss of the volatile solute to particular events during the development of particle morphology.

Initial experiments have been carried out with drops of aqueous solutions of glucose, sucrose, maltodextrin and coffee extract. The results clearly display the onset of the volatiles-retentive selective diffusion phenomenon. There is also substantial loss of the volatile component later in the drying process, when the drops undergo repeated ex ansion, bursting and cratering due to the formation of internaf bubbles. These experiments appear to be the first quantitative demonstration of major losses accompanying changes in drop morphology.     

茶多酚提取方法进展

本文综述了国内外现有茶多酚提取方法的现状以及近期的研究进展，并对其优缺点进行了评价。这将有助于中低档茶的综合利用和茶多酚的进一步开发应用。     

ANALYSIS OF RECENT MEASUREMENTS OF THE VISCOSITY OF GLASSES

Viscosity of Simple Soda-Silicate 500° to 1400°C Comparison of the results given by English with those of Washburn, Shelton and Libman, indicates a discrepancy in the absolute values of log₁₀ viscosity amounting to 0.6, those of Washburn et al., being relatively too high. If correction for this is made, the isothermal curves of log₁₀ viscosity as a function of soda content are smooth up to 50% Na₂O, showing no inflection. The observations as a function of temperature T are all represented within accidental error by an equation of the type where all three constants vary regularly with the composition. Change of Viscosity of Glass (6SiO₂, 2Na₂O) due to Molecular Substitution of CaO, MgO and Al₂O₃ for Na₂O The effect is clearly brought out by plotting (from the results of English) the change of log₁₀η due to the substitution as a function of temperature. The curves each show a sharp bend at a temperature between 840° and 1050°C, which is designated the aggregation temperature T_a. If we divide these curves by the corresponding percentage substituted, we get curves for each oxide which are straight and parallel below the aggregation temperatures, the slopes (increase of change of log₁₀η per 100°C) being −0.056 (CaO), −0.055 (MgO), −0.018 (A1₂O₃) per per cent oxide substituted. For substitution of 1/2 molecule the slopes are −0.325 (CaO), −0.23 (MgO) and −0.18 (Al₂O₃) per 100°. At the aggregation temperature the change of log₁₀η per per cent is a minimum, 0.03 to 0.06 for CaO, 0.12 for MgO, 0.07 for Al₂O₃. Evidence of Aggregation in Glasses, from viscosity Measurements The sharp bends in the plots of change of log₁₀η due to substitution of an oxide for Na₂O, suggest the beginning of molecular aggregation at these temperatures. These aggregation temperatures are close to the devitrification temperatures, but the effect on the viscosity curves cannot be due to actual devitrification since it does not change with time. Taking the aggregation temperatures as equal to devitrification temperatures, additional isotherms are roughly sketched into the equilibrium triangle of the system Na₂O-CaO-SiO₂. Change of Viscosity of Glass (4SiO₂, 2Na₂O) due to of Substitution of B₂O₃ for SiO₂ The change of log₁₀η (from the results of English) is plotted as a function of temperature, and also the change of log₁₀η per per cent B₂O₃. The curves are more complex than for the substitution for Na₂O.     

环氧树脂羟基值测定方法的研究

利用乙酸酐、吡啶和浓硫酸混合的乙酰化试剂测定环氧树脂中羟基值含量的方法具有操作简便、滴定终点明显和分析结果误差小等优点。     

骑式摩托车油箱喷涂工艺的改进

面对日益激烈的市场竞争,摩托车油箱外观质量越来越成为影响销售的因素之一。文章介绍了改进工艺后的油箱涂装,该涂装体系提高了油箱外观的丰满度,降低了油箱涂装的生产成本。     

几种针状焦性能对比

针状焦分石油系和煤系两大类,这主要取决于针状焦的原料来源。在同一系列中由于原料不同和工艺条件不同 ,针状焦的各自性能也不相同。针状焦是生产超高功率石墨电极和高功率石墨电极的主要原料 ,针状焦的性能对石墨电极的质量有至关重要的影响。所以对针状焦性能以及其对石墨电极质量影响的研究十分必要的。以下是常用的几种进口针状焦和国产针状焦的性能对比。１原料性能分析对比原料试样包括４种针状焦 ,其中两种为进口针状焦：三菱针状焦和新日化针状焦;另两种为国产针状焦：鞍山针状焦和锦州针状焦。其中除锦州针状焦是石油系针状焦外…     

聚酰亚胺的合成法

本文评述了缩聚型聚酰亚胺的主要合成方法和近年来国际上在合成中所做的探索。