缝纫增强对碳纤维编织复合材料管件能量吸收性能的影响

采用碳纤维增强复合材料管件代替传统的金属材质的吸能盒,实现了在提高能量吸收能力的同时减轻车身重量。管件的增强体分别是经过缝纫增强的碳纤维编织物和未经过缝纫增强的碳纤维编织物,选用环氧树脂作为基体材料运用真空辅助成型工艺完成整个管件的制作。对有无缝纫增强形式对碳纤维编织物增强复合材料管件物能量吸收能力的影响展开研究。研究结果表明,经过缝纫增强的碳纤维编织管件能够明显提高管件的能量吸收能力,经过缝纫增强的管件的比能量吸收值比未经缝纫增强的高出16%。为了研究管件的能量吸收机理,对测试后的管件进行了树脂包埋、抛光和观察,观察后发现经过缝纫编织的管件物的中央裂纹受到了缝纫结构的限制,使得中央裂纹不易扩展,能量吸收性能得到明显的提高。     

二维编织复合材料管件力学性能研究进展

综述了近年来国内外对二维编织复合材料管件力学性能的研究成果及研究进展,主要包括力学性能实验研究、结构几何模型和数值仿真研究。在实验研究中介绍了二维编织复合材料管件的能量吸收性能及弹性性能,同时重点介绍了编织角及编织结构的变化对复合材料各种性能的影响的最新研究进展;在结构几何模型研究中,以细观结构、宏-细观结构模型研究为主,详细介绍了当前流行的建模方法;在数值仿真研究方面,介绍了研究人员根据二维编织成型原理以及纤维在复合材料中的取向建立的实体模型仿真分析。最后,总结当下研究中存在的问题,并对未来研究趋势进行展望。     

二维编织复合材料管件轴向压缩性能研究

通过优化二维编织复合材料管件复合工艺,制作了碳纤维含量较高的碳纤维复合材料管件,同时对管件进行了轴向压缩性能测试,分析并探讨了编织参数对复合材料管件纤维体积含量及轴向压缩性能的影响。结果表明:优化后的复合工艺可保持复合材料管件纤维体积含量在20%~40%之间,同时使得复合后管件的内径达到一致;在编织速度不变的情况下,随着编织节距的减小,编织角逐渐增加,纤维体积含量逐渐增加,当编织节距减小到一定程度后,纤维体积含量的增加变缓,而轴向压缩强度先升高后降低,当达到最大值时,编织角为46°。     

三维编织碳纤维复合材料剪切性能研究

本文采用短梁三点弯曲试验法,研究三维四向、五向编织碳纤维复合材料的剪切性能、剪切破坏过程及其破坏模式。结果表明:三维五向较三维四向编织复合材料剪切性能好;三维编织复合材料剪切强度沿长度方向随着编织角的减小而增加;切边三维编织复合材料试件受剪切破坏时在加载点附近侧表面裂缝沿纱线走向分布,上下两表面发生弯曲破坏,离开侧表面2 mm后内部纵向截面上下表层发生弯曲破坏,其它部位未发生剪切破坏。     

碳纤维复合材料管件与金属配件销钉连接的研究

碳纤维复合材料因其轻质、高强等性能在汽车领域得到广泛应用。碳纤维复合材料吸能盒作为汽车的重要部件,在汽车装配中与金属配件的连接问题是研究能量吸收的重要方向。为研究能量吸收盒的装配可行性问题,本文采用机械连接中的销钉连接方式首先研究了开孔对管件的能量吸收影响,其次通过正轴向、偏轴向准静态压缩实验分析复合材料管件与金属配件悬垂式与非悬垂式连接的能量吸收性能差异并观察其破坏过程,结果表明,底部开孔对管件能量吸收无较大影响,本文设计的悬垂式销钉连接方式无法稳定有效吸能,不具有可行性,非悬垂式销钉连接方式具有可行性,可采用非悬垂式销钉连接进行进一步研究。     

三维编织结构参数对复合材料拉伸性能的影响

通过7组实验比较和分析研究,评价了编织结构参数(如编织角,纤维体积分数,轴向纱数与编织纱数之比,三维四向/五向,厚度)对复合材料拉伸性能的影响,且对复合材料的破坏模式进行了研究。实验结果表明,三维编织复合材料具有良好的力学性能,编织角、复合材料尺寸、纤维体积含量、轴向纱数与编织纱数之比等对复合材料的性能有较大的影响;复合材料有两种破坏模式,一种是裂纹沿纤维束扩展,另一种是纤维束拉断,后者为主要破坏模式。这些结果为三维编织复合材料的设计提供了依据。     

方管短玻璃纤维增强聚丙烯高压水穿透行为研究

采用方形截面管件,以短玻璃纤维增强聚丙烯为原料,通过溢流法水辅助注射成型实验探究了熔体注射温度、注水延迟时间和注水压力等工艺参数对制件宏观现象的影响机理,并分析了高压水在方形管道中的穿透行为。结果表明,当熔体温度升高时,方管的直角边和斜边残余壁厚都呈减小趋势,但温度过高时会出现管件收缩现象,管件截面中空面积增大且截面形状与高压水的穿透前沿形状一致,偏圆形,但截面的圆率逐渐减小;当注水压力增加时,管件残余壁厚减小,截面中空面积增大,其截面形状随着注水压力的增加逐渐与型腔结构一致,偏方形;当注水延迟时间增加时,管件残余壁厚增大,中空截面减小且管件截面形状也与高压水前穿透前沿一致,偏圆形,但相较另外两个参数,注水延迟时间对方管件的影响程度更小,因而对截面的圆率影响不大。     

增强体结构对缝合编织复合材料剪切性能影响的实验研究

本文主要研究增强体结构对缝合编织复合材料剪切性能的影响。通过对奇数层薄片缝合、偶数层薄片缝合、偶数层厚片缝合3种试样进行实验研究,分析了不同编织物层数、不同编织物厚度对缝合编织复合材料剪切强度、试样破坏时吸收能量的影响。结果表明:偶数层厚片缝合试样不仅剪切强度大于其他两种试样,而且单位厚度所吸收的能量也比其他两种试样多。通过观察3种试样内部的破坏情况可知,偶数层厚片缝合试样发生分层破坏,但在其他两种试样中并无此现象发生。     

三维全五向编织复合材料的弯曲性能研究

以无碱玻璃纤维为原料,采用四步法1×1编织工艺在全自动模块组合式编织平台上制备三维五向及全五向编织物;以E51环氧树脂、70#固化剂(四氢邻苯二甲酸酐)为树脂基体,与编织物复合制备三维五向及全五向编织复合材料;利用Instron万能材料试验机对比测试上述编织复合材料的弯曲性能,研究轴纱、编织角、纤维体积分数等结构参数对材料弯曲性能的影响。结果表明,编织复合材料的弯曲性能随着编织角的增加而减少,随着轴纱、纤维体积分数的增大而增加;三维全五向编织复合材料的弯曲性能明显好于三维五向编织复合材料。     

开孔与螺栓加载的三维五向编织复合材料剪切破坏模式

本文研究了开孔和螺栓加载对三维五向编织复合材料剪切性能的影响。制备了4种样品:无孔编织件、机械开孔无螺栓加载的编织件、机械开孔且分别螺栓加载5次和10次的试件。结果表明:机械开孔只是造成孔边纤维的切断,没有发现其它明显的损伤;螺栓加载不会明显影响材料的剪切性能。材料的破坏模式为:在试样纵向截面内,裂纹的扩展区域成扇形,在纵向截面中裂纹区域长度沿着厚度方向从表面到中部逐渐缩短。三点弯剪切测试后,没有产生明显的分层破坏。在试样表面裂纹主要沿着纤维束编织角方向,而在试样内部裂纹主要沿着厚度方向和纤维束取向方向。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料，介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比，介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序，对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Some Large Wood-Boring Beetles in Southeastern USA

Ethanol and α-pinene were tested as attractants for large wood-boring pine beetles in Alabama, Florida, Georgia, North Carolina, and South Carolina in 2002–2004. Multiple-funnel traps baited with (−)-α-pinene (released at about 2 g/d at 25–28°C) were attractive to the following Cerambycidae: Acanthocinus nodosus, A. obsoletus, Arhopalus rusticus nubilus, Asemum striatum, Monochamus titillator, Prionus pocularis, Xylotrechus integer, and X. sagittatus sagittatus. Buprestis lineata (Buprestidae), Alaus myops (Elateridae), and Hylobius pales and Pachylobius picivorus (Curculionidae) were also attracted to traps baited with (−)-α-pinene. In many locations, ethanol synergized attraction of the cerambycids Acanthocinus nodosus, A. obsoletus, Arhopalus r. nubilus, Monochamus titillator, and Xylotrechus s. sagittatus (but not Asemum striatum, Prionus pocularis, or Xylotrechus integer) to traps baited with (−)-α-pinene. Similarly, attraction of Alaus myops, Hylobius pales, and Pachylobius picivorus (but not Buprestis lineata) to traps baited with (−)-α-pinene was synergized by ethanol. These results provide support for the use of traps baited with ethanol and (−)-α-pinene to detect and monitor common large wood-boring beetles from the southeastern region of the USA at ports-of-entry in other countries, as well as forested areas in the USA.