薄壁铝内衬芳纶缠绕高压气瓶的研制

本文对薄壁铝内衬芳纶纤维缠绕复合材料高压气瓶的设计、工艺制作、试验进行了研究，针对芳纶复合材料低层间剪切强度、易吸潮及高温条件下强度损失大的特点，研究一种高层间剪切强度、耐高温的树脂体系，并对该树脂体系的工艺进行研究，并进行了大量的试验验证，从而得出芳纶纤维缠绕金属内衬复合材料高压气瓶的设计方法和工艺制作方法。同时对金属内衬复合材料高压气瓶的疲劳和早期渗漏进行研究。     

两种不同铝内衬碳纤维缠绕复合材料气瓶受力状况的对比分析

基于复合材料层合板弹塑性分析理论,参考DOT CFFC《铝内胆碳纤维全缠绕复合气瓶的基本要求》标准,利用网格理论设计了容积70L的铝内衬碳纤维缠绕复合气瓶。在相同的预紧力和工作压力下,研究对比分析了两种不同型号铝合金6061和7075作为内衬的气瓶的受力状况。结果表明,铝合金6061作为内衬时,其内衬应力水平分布比较均匀,可以更好地发挥外缠碳纤维的高强度特性,且价格经济实惠,较7075更适合作为复合材料气瓶的内衬材料。     

钢质内胆玻璃纤维环缠绕气瓶内胆强度计算分析

介绍了钢质内胆玻璃纤维环缠绕气瓶的应用、特点及主要材料的相关状况,描述了产品标准的采用情况和目前设计计算中通常采用的方法,阐述了内胆强度计算在环缠绕气瓶强度计算中的重要性;通过对内胆及纤维的受力分析,确定了在环缠绕气瓶爆破压力下内胆和纤维的应力状态以及环缠绕气瓶的爆破形式,并依据内胆材料的应力-应变曲线,提出了内胆强度的具体计算方法。     

复合材料球形气瓶非测地线缠绕线型设计和强度分析

碳纤维复合材料球形气瓶因其较高的比强度、比刚度和抗疲劳性,被广泛应用于航空航天及民用工业领域。基于微分几何理论,推导出满足球形气瓶缠绕基本原理的落纱点轨迹方程,给出缠绕线型轨迹和缠绕角应该满足的稳定缠绕条件,并对缠绕轨迹进行仿真。考虑球壳的变曲率特点,针对球形气瓶缠绕层进行变厚度、变角度的精细化有限元建模,对工作压力下的气瓶内衬和缠绕层各向应力分布进行数值模拟和分析,并预测了气瓶的爆破压强。结果表明,优化设计得到的缠绕线型参数既能满足缠绕工艺的基本要求,又有效提高了球形气瓶的结构力学性能。研究成果对复合材料球形压力容器的设计制造具有重要的意义。     

缠绕张力对薄壁金属内衬复合材料气瓶性能影响

通过薄壁金属内衬的外压强度试验、不同缠绕张力NOL环以及复合材料气瓶的力学性能试验,采用声发射的检测方法研究缠绕张力对薄壁金属内衬复合材料气瓶的疲劳以及爆破性能的影响。结果表明,薄壁金属内衬的外压强度较小,缠绕张力对复合气瓶的疲劳以及爆破性能影响较大,采用声发射信号以及气瓶的性能试验研究可以指导制定最优化的缠绕张力制度。     

高压全缠绕复合材料气瓶自紧优化分析

自紧处理能有效提高复合材料气瓶的疲劳性能和纤维利用率。以容积为140L、工作压力为35.0MPa的全缠绕复合材料气瓶为例,对其自紧压力优化方法进行研究,并采用有限元法对全缠绕复合材料气瓶进行自紧分析。结果表明:同时借助DOT-CFFC和ISO-11119标准可实现34.5MPa以上的全缠绕复合材料气瓶自紧压力的优化;经过最佳自紧压力处理后,35.0MPa全缠绕复合材料气瓶在工作载荷工况下内衬的承载能力和复合材料层的纤维利用率分别提高了42.1%和38.7%。     

复合材料天然气气瓶预紧压力的研究

本文针对铝内衬全缠绕复合材料天然气气瓶,应用ALGOR FEAS有限元分析系统进行了气瓶材料的弹塑性历程分析,设计了气瓶的预紧压力。采用轴对称的应力－应变关系对气瓶金属内衬、复合材料进行了应力分析,确定了气瓶的应力分布状态。研究表明,通过预紧压力设计,降低了铝内衬工作状态下的最大拉应力,实现了提高复合材料气瓶疲劳寿命的目的。     

纤维缠绕高压气瓶的设计及试验

用纤维增强材料制造耐高压气瓶(内压容器)多采用纤维缠绕法。因为纤维增强塑料在高压下气密性不好,所以需要有气密性好的内衬,内衬材料可以是金属(铝、不锈钢等),也可以是非金属材料(如橡胶等)。高压气瓶一般是在使用压力下或在反复充压——卸压的条件下长时间工作,因此要求爆破强度高(安全系数一般要求3～6或更大),疲劳性能好(不渗漏),重量也有限制。     

碳纤维／环氧树脂在橡胶内衬表面的全缠绕工艺设计

根据橡胶内衬碳纤维全缠绕压力气瓶的技术指标,依据网格理论对缠绕层和缠绕张力进行详细的理论设计计算,确定缠绕参数和工艺.选用的环氧树脂体系力学性能优异,其黏度满足缠绕成型工艺要求,同时复合材料NOL环的断面形貌表明该树脂体系与T800碳纤维界面结合良好.对缠绕成型的压力气瓶进行试验,检测表明.水压爆破试验和疲劳试验结果均满足复合材料气瓶的设计要求.     

薄壁内衬复合材料发射筒结构设计与缠绕工艺研究

为了探究碳纤维增强复合材料在单兵筒式武器设计中的应用,开展了薄壁内衬碳纤维增强复合材料发射筒结构设计和工艺技术研究。首先,基于弹性理论和网格理论分别建立薄壁内衬层和碳纤维增强层厚度计算模型;其次,基于纤维增强复合材料损伤过程,分析了复合材料筒身的失效形式,讨论了采用不区分失效形式的Tsai-Wu强度准则和区分失效形式的Hashin强度准则的作用影响;最后,阐述了复合材料发射筒的缠绕工艺流程,重点分析了铺层方式和缠绕张力对纤维缠绕工艺的影响。研究结果可以为复合材料发射筒以及纤维增强复合材料圆筒结构的设计和加工提供参考。     

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.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

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.     

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.     

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。