应用CAESAR Ⅱ进行管道应力分析的几点原则

CAESARⅡ是一款基于结构力学杆状单元进行有限元分析的专业管道应力分析软件,其遵循的标准包括ASME B31.3工艺管道、ASME B31.1动力管道、以及BS806等等。对于国内化工热力行业,一般采用ASME B31.3、ASME B31.1进行管道应力分析校核的计算,本论文着眼于利用CAESARⅡ软件采用ASME B31.3标准进行管道应力分析的情况,对分析计算过程中的一些参数提出了一些需要注意的地方。     

工艺管道应力分析中对偶然载荷的静态处理

依据ASME B31.3—2012和管道应力分析软件CAESARⅡ5.3的计算过程,从一次应力与二次应力概念的角度、摩擦力和约束间隙对管系的影响、支架脱空的影响等方面分析了目前国内外工程公司经常采用的工艺管道应力分析中偶然工况的编辑方法,并提出认为最贴近标准、最合理的处理方法,希望可为今后的应力分析工作提供有益的参考。     

管道应力分析及支管设计研究

承压管道系统高效和安全的运行,保障着各行业管道运输、工艺流程的正常运转。管道系统按照预期目标建设和安装前,对管道系统优化设计,起着至关重要的作用。设计过程不但需要对管道的应力进行分析,评估可能产生的风险,并制定相应的技术措施,还需要进行管道应力校核,防止投入运行后管道产生破损。因此,项目管道系统设计基于ASME B31.3标准,分析了管道应力对管道安全产生的影响,讨论了管道应力的校核标准。并进行了支管模型设计,论述了ASME B31.3标准中支管补强计算的依据、适用范围,通过一个工程实例来分析说明如何确定支管表中需要计算的部分和如何判定补强计算的正确性。     

ASME B31.3压力管道应力分析相关条文的演进探讨

本文从ASME B31.3-2016版工艺管道设计规范管道应力分析相关条文入手,结合相关资料,分析了规范中管道静力分析中的一次应力分析、二次应力分析的理论基础及其演进思路,并结合国内对应规范GB50316-2000(2008版)、GB/T 20801-2006的现实情况,给出了未来的升版建议。     

关于一次应力的余量加到二次应力计算中的讨论

对ASME B31.1及B31.3中关于一次应力的余量可以加到二次应力的计算中这一规定进行了详细的讨论及阐述,并考察了在CAESAR II中激活"liberal allowable stress range"选项对于二次应力计算结果的影响。从结果可知,当该选项被激活时,可以有效解决二次应力超出许用应力范围的情况。     

关于弯头应力增大系数的计算

对弯头的应力增大系数(SIF)进行了研究,利用FEATools软件采用有限元法计算了弯头SIF值,并将计算结果与ASME B31.3进行了比较,为管道应力分析提供有价值的参考。     

多校核准则管系应力分析

管道是工业生产的命脉,由于管道长期承受温度、压力、载荷的影响而容易发生各种失效。管道的敷设方式包含架空以及埋地两种,管道的应力分析评价属于管道定期检验安全评估中的一项重要工作,由于这两种敷设方式管道的受力条件具有明显不同,因此必须对埋地管道和架空管道的标准适用性进行详细的研究。通过利用CAESARⅡ软件建立模型,并采用ASME B31.3-2014《工艺管道》和ASME B31.4-2016《液态烃和其他液体管线输送系统》分别对架空管道和埋地管道进行校核,计算管道的整体应力水平,为工业管道的定期检验提供有力的技术支撑。     

架空蒸汽管道系统应力分析研究

蒸汽是工业生产中常用的一种介质,其热量经常被用来进行各种生产活动。近几年蒸汽管道事故频繁发生,蒸汽管道的安全必须引起注意。TSG D7005—2018《压力管道定期检验规则——工业管道》中明确要求对某些情况进行应力分析,用以评估管道的安全性能。以某工厂蒸汽管道为例,利用CAESARⅡ软件对管道建立模型,计算管道各节点受力及位移情况,并用ASME B31.3-2016《工艺管道》进行校核,依据计算结果制定有针对性的检验方案,对工业管道的定期检验提供有效的数据支撑。     

汽轮机进口管道应力分析

利用CAESARII应力分析软件程序对汽轮机进口管道进行了应力分析,根据ASMEB31.3《工艺管道》标准要求进行应力校核,管口受力按照NEMA SM23进行核定,进而对汽轮机进口管道的布置提出一般性解决方案。     

异种钢焊接斜三通的应力分析

应用Ansys Workbench对异种钢焊接斜三通进行了有限元计算,得到了比ASME B31.3—2014规范更为精确的应力增大系数,从而改进CARSAR II的计算结果,同时对比了同材质钢焊接斜三通的应力增大系数,结果表明:异种钢焊接相比同种钢焊接对应力增大系数的影响程度更大,为管道应力计算提供了一些参考。     

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。