含凹坑压力管道受轴向弯矩时的极限载荷分析

采用ANSYS有限元分析软件对含外壁凹坑的压力管道受轴向弯矩时的极限载荷进行了研究,建立了压力管道有限元模型,检验了有限元模型的计算结果。研究结果给出了管道结构塑性区扩展过程,分析了凹坑几何尺寸对管道极限载荷值的影响规律,结果表明,有限元模型计算结果与实测值比较吻合。     

熔融结晶洗涤塔过滤板的有限元分析

利用ANSYS软件对熔融结晶洗涤塔的主要受力构件——过滤板进行了有限元分析,建立了合理的结构和载荷简化模型.通过有限元分析计算,得到了过滤板的轴向变形和主体应力分布云图,并对过滤板的局部应力和外载荷波动条件下的应力进行了分析.     

考虑温度影响的平盖加筋封头结构应力强度分析

对某加热器的平盖加筋封头考虑其既受热又受内压的情况,运用有限元分析软件ANSYS对其在两种载荷下分别单独进行应力强度分析,并重点介绍了热应力分析方法。运用ANSYS耦合分析功能,在两种载荷同时作用下对平盖加筋封头结构进行应力强度分析。分析了温度载荷对平盖加筋封头结构应力强度的影响。     

外载荷作用下大开孔接管应力计算精度的影响因素分析

以在内压与外载荷作用下的圆柱壳上一大开孔接管为例,基于ANSYS软件中APDL语言建立了其有限元模型,研究了单元类型、单元技术、网格密度、施加外载荷方法等因素对计算的应力与位移的影响,同时将计算结果与薄壳理论解进行了对比。计算结果表明,以上4种因素对有限元分析结果影响较大。在网格划分密度较大情况下,优先选择Solid186单元全积分单元技术或Solid185单元增强应变单元技术;外载荷施加应采用RBE3命令。模拟结果可为外载荷作用下接管应力分析提供一定参考依据。     

弯管端部管道外载荷的平移处理及有限元分析

接管与壳体连接部位的局部应力校核评定是压力容器设计中经常遇到而又十分重要的问题。在进行局部应力校核时,软件需要输入的管道外载荷与载荷条件的给定值往往不一致。介绍了弯管端部载荷等效平移到直管端部的处理方法,并使用ANSYS有限元分析软件建立了三维模型,对载荷平移前后的结果进行了验证,验证结果显示该公式有效可行。     

子午线轮胎的有限元分析

采用ANSYS软件非纡性分析技术,通过三维体单元,层单元和接触单元建立了子午线轮胎（205／60R15）的三维有限元模型,并对自由轮胎充气,接地轮胎受长直载荷和受力水平推动力等工况下轮各部位的应力及变形进行了分析,得到了各种情况下轮胎上应力和应变的分布状况。     

基于ANSYS的管道变形应力分析

对某公司埋地管道受外部载荷作用发生变形这一问题,借助于ANSYS软件的应力分析功能,通过施加位移载荷求出管道变形后的应力分布,为管道的安全评价提供依据。     

管道受坠物冲击载荷作用的数值模拟基本方法

管道受冲击载荷作用是复杂的非线性接触问题,本文介绍了可以进行非线性分析的有限元软件、离散元软件的概况和基本原理,以及运用它们对冲击载荷作用引起的管道动力响应过程进行数值模拟的基本方法。     

“人”形三通的应力计算与强度分析

通过对"人"形三通建立模型并进行应力分析,阐述了使用ANSYS有限元分析软件对特殊管道构件进行静力分析的一般方法和具体步骤。对该三通在内压作用下的应力进行计算,并分析其应力与变形云图,得出"人"形三通结构在内压载荷下的应力分布规律,了解其应力危险区域及变形情况。并在有限元分析模型的基础上对原有三通结构进行了改进,获得一种优化结构。分别计算未优化三通与优化后三通在10组不同内压条件下的最大应力值,对比发现优化后的三通应力水平得到显著改善。     

基于ANSYS的往复压缩机管系振动分析

对用于管道应力计算的各种软件进行了简要分析,并选择了使用ANSYS软件对往复压缩机管系振动进行分析在对往复压缩机管道系统中各元件力学特性进行简要分析的基础上,介绍了ANSYS软件中用于管道建模的主要单元和命令通过实例,介绍了ANSYS软件在往复压缩机管道系统振动分析中的应用,结果表明该方法方便简捷,可用于往复压缩机管道系统振动分析及防振设计。     

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.     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.