换热器异形法兰应力分析

以某型号换热器的异形法兰为研究对象,应用有限元软件ANSYS分析了稳态条件下异形法兰的温度场,并计算了该异形法兰在温度载荷与压力载荷作用下的应力分布。根据ASME规范对异形法兰的危险受力部位进行了强度评定,结果表明,换热器异形法兰的强度满足安全要求。     

超高压压缩机管道内气流脉动的应变片测量方法研究

由于超高压压缩机管道压力高,且很多介质为易燃易爆介质,出于安全性考虑,超高压管道的压力脉动一般不允许采用动态压力传感器侵入管道进行直接测量,只能采用间接测量的方法。本文对采用应变片测量管道表面应变,进而间接测量管道压力脉动的方法进行研究。首先,在静水压条件下,对管内压力—表面应变的关系进行标定。在该条件下,通过应变片测量得到的管内压力与管内实际压力的误差小于3%。然后,根据该标定关系对超高压压缩机管道的气流脉动进行测量。测量得到二级进气管道近气缸处脉动峰-峰值为21%,二级排气管道近气缸处的脉动峰-峰值为27%,脉动频率主要集中在前3阶。将测量得到的管内脉动压力作为振动激励,对二级进气管道振动应力进行有限元仿真。结果表明,有限元模型计算所得的管道表面应变与测量值在时域及频域特性上吻合较好。上述研究表明采用应变片测量压力脉动的方法具有一定的准确性,能较好地测量管道压力脉动的幅频特征,具有工程应用的可行性。     

含缺陷压力管道应力分析及合于使用评价方法的研究

为保证在用工业管道的安全运行,需要对含缺陷管道进行应力分析和安全评估。通过介绍GB/T 20801.3-2020中的应力分析的计算方法与评定准则以及GB/T 19624中的缺陷安全评定方法,并基于国产有限元分析平台将国标计算过程软件化,开发了管道应力分析和缺陷评估软件。针对某化工管道检出的未熔合超标缺陷,利用软件开展了应力分析和缺陷安全评估。分析结果表明:该缺陷满足合于使用评价要求,可以在下一个检验周期内安全运行。     

高压断路器壳体翻边接管的强度分析

用应变电测方法在断路器壳体的关键部位贴应变片,进行了最高测试压力为4MPa的常温水压试验,测试了关键部位的应力分布情况;用ANSYS10．0软件建立了相同尺寸壳体的计算模型,研究了壳体在内压作用下沿3个关键截面的应力分布状态,井和试验结果进行了比较、验证,得到了该设备大开孔部位的应力分布曲线;根据JB4732-95《钢制压力容器——分析设计标准》的设计准则,对此大开孔结构进行了强度评定。结果表明,该壳体强度能满足安全要求。     

真空平板玻璃支撑应力理论分析与实验研究

用弹性力学的结点法建立真空玻璃支撑应力-应变数学模型,求出真空玻璃的支撑应力-应变场,分析了其应力-应变分布规律,同时用电测方法进行试验验证。试验结果表明,真空玻璃最大应力发生在四角的第2个支撑处,最大应力弹性力学计算值11.057MPa,电测法的测试值11.765MPa,两者误差为6.02%。支柱横截面上的正应力为179MPa,纵向变形分别为0.2686μm(钢柱)和0.7414μm(玻璃柱)。控制支撑高度误差和玻璃的平整度,保证受力的均匀,可增加真空玻璃的强度,增加其可靠性,提高其使用寿命。     

往复式压缩机管道内压力脉动的测试与分析

通过对管道内压力脉动的实验测试及测点信号的时域分析和频域分析 ,计算出了压力不均匀度。测试结果证实 ,往复式压缩机管道内压力脉动总是存在的 ,其特征频率为压缩机激发基频的倍频 ;对测试的压力脉动值与有限元理论计算值比较 ,其结果是相当吻合的     

碟式分离机转鼓的应力分析与结构研究

本文采用轴对称有限元方法计算了DZY—50型碟式分离机转鼓主要零件在各种工况下的应力,并采用三维等参有限元方法计算了本体排渣口部位以及锁环锁紧槽口部位在恶劣工况下的应力。在确定各零件的力学模型时,根据变形协调条件求出了锁环和本体的相互作用力。为了验证有限元计算的可靠性,采用电阻应变测试技术在高速试验台上测试了转鼓实物在各种工况下的应变,并由此得出应力。文中介绍了实验装置、动应力测试技术以及实验数据的处理。实验结果与有限元计算结果比较表明,二者是相当一致的。在计算和实测的基础上,对转鼓的结构和强度进行了分析,并提出了局部结构改进的建议。     

耐火材料高温弯曲应力-应变关系测试方法及影响因素

介绍了耐火材料弯曲应力-应变测试仪的基本构成以及对试验炉、加荷装置、变形量测量装置和计算机控制系统等各构件的要求;重点介绍了使用该仪器研究耐火材料应力-应变关系的方法以及影响测试结果的相关的因素。该方法可以用来研究耐火材料在高温下承受弯曲应力时的变形问题,确定耐火材料在各温度下的应力-应变关系,测试和判断耐火材料的弹性、塑性和粘滞流动的温度范围,并根据应力-应变关系计算耐火材料在不同温度下的弹性模量。     

含体积型缺陷管道安全评价技术研究

为研究体积型缺陷对管道安全性的影响，通过Workbench软件，结合管材的应力–应变曲线和塑性失效准则，对缺陷管道的最大等效应力和失效压力进行了评价，考察了倾斜角度、腐蚀深度、腐蚀长度等参数变化对管道局部应力分布的影响。结果表明，当缺陷具有一定倾斜角度时，缺陷左右拐角处的高应力集中最为明显，上下拐角处的低应力集中最为明显，缺陷沿轴向分布时对管道的危险性更大；腐蚀深度与最大等效应力和失效压力呈线性关系；腐蚀长度和腐蚀宽度的变化对最大等效应力和失效压力的影响有限，随着腐蚀长度的增加，最大应力点从缺陷内边缘转移至缺陷中心；在有限元分析范围内，各因素对管道安全性的影响程度依次为倾斜角度、腐蚀深度、腐蚀长度和宽度。研究结果可为提升管道完整性管理水平提供技术思路。     

中高强度压力管道腐蚀缺陷剩余强度评估方法的对比研究

本文分别采用ASME B31G-1984、修正的ASME B31G准则、许用应力法、PCORRC以及有限元方法对中高强度压力腐蚀管道进行管道失效压力的计算,并对以上几种方法的适用性进行分析。结果表明,ASME B31G-1984和PCORRC法具有很强的保守性,修正的B31G方法的计算结果有所改善,但是总体还是偏于保守;许用应力法保守性较小,比较适用于中高强度等级的管道剩余强度的评价;用有限元方法计算得到的管道失效压力最接近于管道的爆破试验压力,总体误差最小,准确度最高,因此在计算中高强度腐蚀管道的剩余强度时推荐使用有限元方法。     

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.     

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.