对称玻璃钢大锥环内固化成型研究及数值模拟

采用有限元方法对复合材料对称玻璃钢大锥环内固化成型进行研究,基于ANSYS仿真软件编写了对称玻璃钢大锥环内固化过程仿真程序,实现玻璃钢大锥环内固化过程温度和固化度变化的数值模拟。结果表明,数值模拟得到的结果符合内固化变化规律;贴近实验数据,模拟准确有效;根据仿真结果得到了玻璃钢大锥环内固化温度变化规律、固化峰值温度随厚度变化规律及锥环不同厚度固化度的变化规律,分析了600~660MW汽轮发电机的玻璃钢大锥环采用内固化工艺能达到完全固化的厚度范围。该研究为玻璃钢大锥环实现高效、低成本成型提供了新方法。     

薄壁金属内衬复合气瓶自紧压力的有限元分析及性能研究

本文研究自紧压力对薄壁金属内衬复合材料气瓶性能的影响规律。采用有限元分析方法对气瓶的自紧过程进行数值模拟,缠绕成型复合材料气瓶,进行水压疲劳及爆破试验验证,并在试验过程中引入声发射监测。试验及分析结果表明,自紧压力对薄壁金属内衬复合材料气瓶的疲劳及爆破性能影响较大,自紧压力过大会使得气瓶复材层出现树脂开裂、纤维断裂等损伤,导致复合气瓶爆破强度值下降。疲劳试验结果表明,自紧压力过大容易导致薄壁内衬提前进入屈服状态,降低疲劳寿命。针对薄壁金属内衬复合材料气瓶,其自紧压力的选取必须充分考虑金属内衬在自紧及工作过程中的应力值,使其在合理区间。     

纤维环向缠绕复合材料气瓶冲击阻抗性能研究

新能源汽车用复合材料气瓶采用复合材料/金属混杂结构,其冲击损伤特性与采用纯复合材料结构有很大的不同,本文结合复合材料气瓶和试板模拟试验,采用冲击能量吸收率、分层损伤扩展阻力、剩余强度比衰减指数等参数作为其冲击阻抗性能的评价指标。采用不同的支撑夹具对玻纤/环氧单向板进行落球冲击试验,以模拟复合材料气瓶的不同材质内胆对纤维缠绕层冲击损伤的影响。研究发现,在一定冲击能量作用下,改变复合材料/金属混杂结构的形式能使其冲击能量吸收率发生变化,并可提高层合板的冲击损伤临界值,即提高其冲击承载能力;冲击能量吸收率越高分层损伤扩展阻力越小,且含冲击损伤层合板的剩余强度衰减越快。因此在设计复合材料气瓶时,需要考虑复合材料/金属混杂结构对分层损伤扩展阻力和冲击能量吸收率的影响。     

挖补角度对复合材料修补片固化过程温度和热应力的影响

利用有限元方法,数值模拟了不同挖补角度的树脂基复合材料修补片热固化过程中的温度场和热应力场,并分析了挖补角度对修补片的温度、固化度和热应力的影响。仿真计算结果表明:挖补角度越小,修补片中心点处的温度峰值越大,固化速率越快,热应力越大;挖补角度越小,修补片非中心点处的固化速率越快,热应力越小,且挖补角度对非中心点处的热应力影响较大。综合分析后可知,在一定挖补角度范围内,合理选择挖补角度,可控制修补材料内部热应力,并获得较好的复合材料修补质量。研究结果为实际修理提供了良好的数值依据。     

树脂基复合材料内外协同固化工艺仿真与分析

在采用传统内固化工艺对厚壁壳体成型时,内层温度往往不足以满足其固化要求或者加热时间过长,因此通常采用多次缠绕多次固化的成型工艺,耗能高、效率低,不但大大提高了成本,也难以保证产品质量。因此本文提出了内外协同固化新工艺并介绍其原理,建立纤维树脂复合材料厚壁壳体内外协同固化过程的传热模型和固化动力学模型,通过有限元软件ANSYS和APDL语言开发内外协同固化过程数值模拟程序,实现了厚壁壳体内外协同固化过程中温度和固化度的分布及其变化规律的数值模拟研究。对新工艺的数值模拟结果表明,随着外温和预热温度的不断增大,中心节点的温度、固化度和应变波动较大;厚壁壳体内外协同固化的时间很短,是传统固化时间的1/3。     

纤维缠绕车载CNG气瓶的结构设计及其有限元分析

根据薄膜理论分析了气瓶封头的椭球比对气瓶强度和稳定性的影响,依据网格理论,结合气瓶容积、使用空间以及实际生产工艺等约束条件,确定了气瓶的内衬几何尺寸、纤维缠绕层的纤维厚度和缠绕角度。最后利用ANSYS中的参数化设计语言(APDL),分别对各种工况下的强度、稳定性进行了仿真模拟和数值计算分析。结果表明,设计的70L纤维缠绕车载CNG气瓶的强度、稳定性满足铝内衬全缠绕碳纤维增强复合材料气瓶的基本要求(DOT-CFFC)。     

长管拖车用大容积环缠绕复合材料气瓶充气及冷却过程温度变化的数值模拟研究

建立了压缩天然气车(CNGV)用大容积环缠绕复合材料气瓶的充气温升数值模型,通过计算流体力学软件Fluent17.1进行数值仿真,模拟1800 s充满20 MPa、2500 L的CNG气瓶的填充过程以及5400s的静态冷却过程。详细介绍了该有限元模型的设置过程,重点分析了气瓶内气体流向、温度分布,以及充气及冷却过程的壁面温度状况,模拟结果表明,大容积气瓶的高温区域集中在瓶尾,该工况下的充气不会使气瓶壁面温度超过许用温度。     

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。     

基于连续编织-缠绕-拉挤成型工艺的复合材料直管固化研究

根据复合材料固化成型原理,建立采用连续编织-缠绕-拉挤成型工艺生产的复合材料直管的传热模型以及固化动力学模型,利用有限元软件ANSYS和APDL语言开发复合材料直管固化过程数值模拟程序,以三维复合材料直管为模型进行固化数值模拟仿真,从而分析不同参数对采用连续编织-缠绕-拉挤成型工艺复合材料直管固化成型过程中的温度与固化度的影响。通过对复合材料直管模型进行固化数值模拟仿真分析可以得到工艺参数(如初始温度、加温历程、拉挤速度等参数)对固化过程的影响规律。对应用连续编织-缠绕-拉挤成型工艺生产的复合材料直管进行在线温度测试,测试结果表明数值模拟与实际生产工艺贴合,对实际生产有指导意义。     

金属内衬碳纤维全缠绕气瓶的有限元分析

本文通过有限元的分析方法,对具有铝合金内衬的碳纤维全缠绕复合材料气瓶的结构进行了剖析,建立了较为合理的复合材料气瓶有限元模型,对气瓶模型的基本建模分析过程进行了阐述和研究。采用ANSYS参数化编程语言(APDL)对复合材料气瓶进行参数化建模,参考美国制定的DOT-CFFC标准《铝内胆碳纤维全缠绕复合气瓶的基本要求》,对公称工作压力、试验压力和最小爆破压力下的碳纤维缠绕铺层和铝合金内衬的各向应力分布进行了数值模拟和计算,并预测了复合材料气瓶的实际爆破压强。     

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。