压力管道焊缝残余应力的优化分析

采用ANSYS耦合单元对压力管道焊缝残余应力进行了优化分析,得到了预热和焊接速度对焊缝残余应力的大小和分布的影响:对试件进行预热可以降低焊接残余应力;较快的焊接速度也可以降低焊接残余应力。该优化分析为进行实际焊接过程提供了指导,为焊接前节省了大量实验时间。实际焊接过程中也验证了计算机模拟的结果和最后焊接后实测的结果比较一致。     

塑料制品残余应力的光弹测量和数值模拟

聚碳酸酯塑件广泛应用于光学、光电和电子领域，但残余应力可导致最终产品光学性能的下降。相对于聚甲基丙烯酸甲酯，残余应力对聚碳酸酯注塑件有更明显的影响。本文首先用偏光设备观察了透明聚碳酸酯注塑件残余应力的分布，以此来研究流动残余应力和热残余应力的影响以及它们之间的相互作用。然后基于光弹实验的结果，用数值方法研究了不同成型条件下的流动残余应力和热残余应力。试验获得的条纹数目和条纹形式，和模拟的结果一致，表明了流动方式、不平衡的温度分布导致聚碳酸酯注塑件产生残余应力的产生。     

第15届全国残余应力学术交流会第1轮通知

机械零构件和电子元器件在制造过程中不可避免地产生残余应力问题，适当的残余应力可能成为服役的有利因素，不适当的残余应力则可能导致变形和失效。残余应力的引入、消除、控制、以及测试和表征等问题在众多制造和应用行业、高校及科研单位日益受到重视。在新材料及新工艺的开发过程中，也迫切需要研究残余应力问题。几十年来，我国残余应力研究与应用取得了卓著成果，累计发表论文数千篇，出版了多部与残余应力有关的学术专著。     

真空平板玻璃封边残余应力的研究

 以实验室制样的真空平板玻璃为基础，用电测法对真空平板玻璃封边结构进行了残余应力场研究，成功测试 出了封边残余应力场的分布。采用数值分析法对真空平板玻璃封边残余应力场进行了分析，采用有限元法分析已建 立的数学模型，得出了其应力分布规律，并得出理论计算与试验结果基本一致的结果。探讨封边料的线膨胀系数对 真空玻璃残余应力的影响，同时分析封边应力耦合对真空玻璃残余应力分布的影响，以残余应力作为评估真空玻璃 失效的基本参量，揭示残余应力强度与弹性模量之间的关系，创立一种基于残余应力的真空平板玻璃失效计算新方 法，为真空玻璃封边残余应力的许容值分析提供理论基础。     

压力容器焊接残余应力的实验研究与理论分析（上）

综合介绍了压力容器焊接残余应力研究现状，提供了一试验容器环焊缝、纵焊缝和接管焊缝残余应力的测量结果和对结果的初步分析。综合考虑了残余应力影响因素后，对容器环焊缝焊接残余应力的计算，提出了一种简化模型。经与工程实测结果对比，该模型给出略为保守的结果。     

纤维增强聚合物复合材料界面残余热应力研究进展

本文综述了聚合物基纤维复合材料界面残余应力的形成，测定方法和各种理论分析方法，阐述了界面残余应力对办面粘结强度以及复合材料断裂韧性和强度的影响，最后对界面残余应力的控制方法作了评述。     

三轴多级循环加卸载下红砂岩强度与变形特征试验研究

为研究围压及应力路径对多级循环加卸载下红砂岩的变形破坏特征的影响,采用RMT-301岩石与混凝土力学试验系统,对红砂岩在10 MPa、20 MPa、30 MPa、40 MPa围压下进行常规三轴压缩试验和等下限增幅循环加卸载试验、增下限等幅循环加卸载试验。研究结果表明:等下限增幅循环加卸载、增下限等幅循环加卸载下试件均呈脆性破坏,强度特性随围压的变化趋势基本一致,试件的加卸载变形模量总体上均随围压增大而增大;随着应力级数增加,等下限增幅循环加卸载下,加卸载变形模量呈先增加后降低或一直降低的趋势,而增下限等幅循环加卸载下均呈增加趋势;随着循环次数的增加,试件的轴向残余应变呈阶梯式增长,且在每级应力循环中呈对数型增长;每级应力的第一次循环对试件损伤影响最大,轴向残余应变显著增长,且增下限等幅循环加卸载下增长更为显著;试件在每级应力循环的轴向残余应变增量随应力级数的变化趋势不同,等下限增幅循环加卸载下呈先减小后增大的“V”形变化趋势,而增下限等幅循环加卸载下总体上呈一直增大的“ノ”形变化趋势,且围压越大变化趋势越明显。     

聚乙烯管材残余应力的定性和定量评价

研究了冷却速度、挤出速度和拉伸比等不同挤出工艺对管材物理性能及残余应力的影响，结果表明，随着冷却和挤出速度的增加，PE管材纵向回缩率增大，静液压和SCG破坏时间逐渐降低。通过盲孔应变法研究了不同挤出工艺对管材内外层的释放应变和残余应力分布的影响，研究表明，采用理想化的均匀分布模型不适用于残余应力的定量评价，采用非均匀应力分布模型计算得到的管材外层的残余应力随着冷却和挤出速度的增加而增大，而管材内层的残余应力变化较小，由于管材沿壁厚方向冷却速度的不均匀，内外层残余应力分布存在差异。最终，通过对管材内中外层分别进行拉伸、密度和结晶度等物理性能试验，进一步证明了盲孔法定量评价残余应力的有效性。同时试验发现，当挤出拉伸比太高时，分子链取向严重，管材纵向回缩率增大，静液压和耐SCG性能下降，管材外层残余应力的最大值为14.6 MPa,与材料拉伸屈服强度相比，提高了50%。     

金属基烤瓷牙冠残余应力产生的原因与控制方法

详细分析了金属基烤瓷牙冠残余应力产生的原因，认为金属与烤瓷热膨胀系数不匹配，制备工艺不合理以及金属与烤瓷结合欠佳等是产生残余应力和导致烤瓷破坏的主要原因，并对如何控制残余应力，关少烤瓷开裂和肃落进行了论述。     

循环拉伸下形状记忆合金纤维增强ECC的闭缝性能研究

将不同掺量和不同直径的形状记忆合金(SMA)纤维埋入工程水泥基复合材料(ECC)制得形状记忆合金纤维增强工程水泥基复合材料(SMAF-ECC),通过单轴循环拉伸试验研究SMA纤维直径和纤维掺量对SMAF-ECC试件拉伸应力-应变关系、残余应变、裂缝宽度和裂缝恢复率的影响。结果表明：打结形SMA纤维的加入提高了ECC的极限应变和极限抗拉强度；提高纤维掺量可有效提高SMAF-ECC试件的应变和裂缝恢复率，试验所得试件的最大应变恢复率和裂缝恢复率分别达到69%和77%;纤维直径在一定范围内增长，可以提高应变和裂缝恢复率，纤维直径过小会导致恢复率减小。研究成果为新型SMAF-ECC试件的推广应用提供了理论依据。     

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。