轿车轮胎水滑现象仿真技术的研究

以轿车轮胎为研究对象,采用Abaqus软件CEL技术,研究带花纹轮胎和光面轮胎稳态自由滚动和瞬态滚动的建模技术,实现轮胎水滑现象仿真。分别对不同行驶速度、不同积水深度下带花纹轮胎的水滑现象进行仿真,通过对比不同情况下轮胎与路面的垂直接触力以及带花纹轮胎与光滑轮胎的水滑现象表明,该仿真技术可靠,适用于带花纹轮胎和光面轮胎水滑现象的研究。     

不同路况对轮胎稳态滚动影响的有限元分析

采用Abaqus有限元分析软件建立11.00R20轮胎的三维稳态滚动模型。根据不同路面附着因数和滑移率的关系曲线定义相关参数,模拟干燥沥青路面、土路及薄雪覆盖路面轮胎行驶过程,重点分析轮胎在不同行驶路况下从静态接地、制动、自由滚动到驱动整个过程中接地法向应力、剪切应力和轮胎自由滚动半径的变化。结果表明,无论是制动还是驱动,路面越光滑,轮胎的接地法向应力和剪切应力分布越均匀,最大法向应力和剪切应力越小,自由滚动角速度越大,自由滚动半径越小。     

计及胎面花纹的子午线轮胎接地性能有限元分析

采用Abaqus软件建立带有部分胎面花纹的三维轮胎有限元模型,模拟研究不同工况下子午线轮胎的接地性能.研究结果表明：轮胎在静负荷和自由滚动工况下应力分布相似,沿轮胎中分面基本对称,最大应力在胎肩部位;在驱动工况下,高应力区向轮胎前进的反方向扩展,制动工况与此相反;在斜坡路面的应力分布与自由滚动时相似,但最大应力有所提高;侧偏滚动工况下的应力主要分布在轮胎的中分面及与侧偏方向相同的一侧,应力值明显提高.     

不同花纹轮胎水滑特性分析

以205/55R16子午线轮胎为研究对象,选用Abaqus软件建立轮胎有限元模型,采用先隐式后显式的方法对5种花纹轮胎进行水滑特性分析。结果表明:基于欧拉-拉格朗日方法(CEL)的轮胎滚动模型可实现轮胎花纹排水的流-固耦合仿真,可较好地预测轮胎行驶时的水流印痕;5种花纹轮胎排水能力由大到小的顺序为纵向沟槽花纹轮胎、正向V形花纹轮胎、反向V形花纹轮胎、纵向S形花纹轮胎、横向S形花纹轮胎;随着轮胎行驶速度的增大,轮胎与路面的接触区从完全接触区向完全上浮区转变。     

有花纹的载重子午胎滚动接地性能有限元分析

采用通用有限元软件ABAQUS,对有花纹的385/65R22.5载重子午线轮胎进行了稳态滚动有限元分析,在有限元模型中考虑了轮胎结构的几何非线性、橡胶材料的超弹性及轮胎与路面接触的非线性边界条件。分析了385/65R22.5轮胎在纯纵滑稳态滚动状态下的力学特性,如纵向力与驱动滑移率的关系以及不同的滑移率下轮胎接地印迹接触压力的分布及接地印迹形状的变化。     

翻胎胎面花纹的选择

汽车依靠轮胎支撑在路面上,而直接与路面接触的是轮胎花纹。轮胎不仅承载、滚动,而且通过其花纹块与路面产生的摩擦力,成为汽车驱动、制动和转向的动力之源。     

Fluent软件的二次开发及其在轮胎流场分析中的应用

通过vc++平台对Fluent相关软件进行二次开发,实现对轮胎花纹块流体动力学分析的整体控制,并开发出一个罔形界面,简化了操作过程。轮胎花纹块在路面滚动时的流场情况模拟结果表明,气动性能随花纹块结构的变化而改变。     

基于滑行法的乘用轮胎通过噪声试验研究

为研究轿车轮胎噪声的影响因素,在同一辆试验车上换装不同品牌/规格的轮胎进行滑行噪声试验,测量不同车速、轮胎花纹、轮胎尺寸的轮胎滚动噪声,有针对性地对不同花纹/规格的轮胎进行比较分析。结果表明:轮胎噪声声压级不是受单方面参数影响产生变化的,不同尺寸和花纹的轮胎都具有独特的轮胎噪声特性,轮胎滚动噪声与车速成正比趋势增大,但某种特定情况下会出现噪声奇点;轮胎花纹对轮胎滚动噪声的影响比较复杂,不同类型的轮胎花纹对噪声影响的权重也不尽相同;轮胎断面宽度几乎与轮胎滚动噪声成正比,在保证花纹、材质相同的前提下,更宽的轮胎断面会引起更大的轮胎撞击噪声和发声机理更为复杂的轮胎花纹噪声。     

子午线轮胎在混凝土路面上的稳态滚动分析

以MSC.Marc软件为平台建立轮胎有限元模型和混凝土路面模型,分析轮胎在混凝土路面上的静态载荷施加过程、自由滚动过程、完全刹车过程和牵引过程,得到轮胎接地面的接触应力分布情况及轮胎角速度与牵引力之间的关系等。模拟结果有利于了解轮胎的力学特性,以便进一步优化轮胎结构,提高轮胎性能。     

冬季轮胎新品介绍

英国《轮胎与配件》2007年9期66页报道：中国台湾南港轮胎股份有限公司推出的全新冬季轮胎产品——SonarPolarFox（PF-1）无镶钉冬季轮胎如图1所示。这款轮胎胎面花纹采用带有三维刀槽花纹的单向胎面花纹结构,在降低胎面花纹块刚性的同时可以提高轮胎在冰路面条件下的性能,胎面中央部位的箭头式花纹及曲折花纹沟槽进一步提高了轮胎在冰雪路面上的牵引性能。     

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。