复合材料U形梁成型模具设计

以复合材料U形梁为研究对象,综合考虑模具材料与复合材料热膨胀系数的差异、模具的结构形式、回弹角补偿以及构件脱模等因素,采用CATIA三维软件对复合材料热压罐成型模具进行数字化设计。模具为框架式阳模结构,采用Q235钢焊接制造,对模具成型曲面进行补偿修正从而减小或消除热压罐成型过程中构件的变形,对两侧缘条各设置1°回弹补偿角以保证U形梁的尺寸精度和脱模要求。该模具结构合理,成本低,可加工性好,型面公差符合要求,具有良好的刚度和气密性。经工艺验证,采用该模具生产制造的复合材料构件型面公差符合要求,U形梁变形角度控制在技术要求范围以内,满足产品技术条件和后续装配要求。     

复合材料自动铺丝轨迹规划

本文针对复合材料回转体类构件,提出了回转体构件自动铺丝轨迹规划算法。应用管道的数学模型,建立了基于三次样条插值的自动铺丝轨迹规划模型。首先探讨了通过三次样条插值对芯模中心线方程的求取,进而建立芯模参数曲面方程,最后提出适用于回转体类构件的铺丝路径生成算法。应用本文的研究成果,在MATLAB中完成实例验证。结论表明,该算法生成的铺丝轨迹能够满足实际铺丝的工艺要求和工程需要。     

自动铺丝构件缺陷形成机理的研究进展

自动铺丝是一种重要的复合材料自动化成型方法,可实现连续变角度铺放,适合大曲率复杂构件的制造,但成型质量受到了多种工艺参数的影响。本文从自动铺丝预浸料的粘弹性和流动性、结晶度、铺层的层间剪切强度、残余热应力以及最大弯曲力等方面对自动铺丝构件成型缺陷的形成进行了表征和机理分析;给出了影响构件成型缺陷的工艺参数,并总结了工艺参数优化方法的研究进展。最后,对自动铺丝构件成型缺陷形成机理的未来研究方向进行了展望。     

复合材料多筋角盒模压成型模具设计技术研究

多筋角盒作为结构连接的重要部件之一,对其尺寸精度和力学强度有较高要求。复合材料具有强度高、密度小、耐腐蚀等优点,成为多筋角盒的理想选择之一。模具设计过程是复合材料多筋角盒成型设计的关键环节。本文主要通过多筋角盒整体结构分析、现有模具结构比较分析、模压模具总体设计与型腔设计、模具的制造与成型、模具的铺层分析五个主要方面的分析,根据模压成型原理,研究并设计出一种可一次成型多件多筋角盒的模具。该套模具的设计大大提高了生产效率,有效解决了产品成型过程尺寸精度差、结构强度不足的问题。     

基于复杂类回转体90°纤维轨迹规划算法研究

铺放轨迹设计是控制自动铺丝工艺质量的关键,为进一步提高复杂类回转体复合材料构件轨迹铺放质量,提出以类回转构件的形心曲线为基准参考线,综合考虑角度偏差、轨迹间距及轨迹测地曲率的多目标轨迹规划算法。根据丝束宽度、丝束数量等工艺参数生成满足工艺要求的基准轨迹,通过对基准轨迹偏移生成偏移轨迹并对其进行局部调整和全局优化,设计其他轨迹。最后以Visual Studio 2010为开发平台,利用CATIA Automation技术开发了复杂类回转体铺放软件,并在复杂类回转体曲面上进行了验证,结果证明了该算法的有效性。     

复合材料壁板的数字化成型研究

以复合材料壁板类零件制造为例,介绍了数字化制造成型方法,研究了该方法在工艺仿真设计、模具设计制造、预浸料裁剪、铺贴等工艺环节中软件和数字化设备的应用过程,并对其制造精度和误差进行了定性分析。研究表明,通过复合材料数字化设计制造一体化软件(Fiber SIM)进行数字化设计与制造,打通了复合材料设计、裁剪、铺贴等数字化制造过程,改变了复合材料传统的制造模式,实现了模拟量向数字量传递,制造精度显著提高,同时缩短了制造周期,减少了人力投入。     

氦质谱检漏技术在复合材料成型模具上的应用

介绍了氦质谱检漏技术,简述复合材料成型模具制造过程及其所用的气密性检测方法,对比分析得出采用氦质谱检漏仪对复合材料成型模具进行气密性检测在检测精度、检测成本、检测周期等多方面具有优势,因此将氦质谱检漏技术应用于复合材料成型模具气密性检测具有很大意义。对氦质谱检漏技术在国内外复合材料成型模具上的应用情况进行介绍,在此基础上,对应用于复合材料成型模具气密性检测的氦质谱检漏系统进行设计,并开展检漏实验,总结检漏过程的注意事项。     

双头铺放轨迹后处理技术研究

为提升自动铺放装备工作效率并提高铺丝机工作的灵活度,对双机器人协同的类转体构件铺丝成型技术进行研究,提出了一个满足协调约束的轨迹预选机制。在确定了双机器人横向移动的配合方案后,以机器人平台可达空间的限制作为约束条件,通过夹角控制对铺丝轨迹进行配对编码并验证。同时得到完整模具的轨迹分配方案,将CAD软件生成的铺放信息转化成机器人角度的加工文件。文中模型证明所提方法满足大型类回转体构件铺放生产的工艺要求,大大提高了铺放效率。     

复合材料带曲率C型梁热隔膜预成型试验与仿真分析

随着复合材料自动铺带和铺丝技术的成熟,并且广泛应用于复合材料结构的生产与制造。通过与铺带或铺丝技术相结合使得复合材料热隔膜预成型技术成为制作L型、C型,Z型等细长零件的重要手段,此种方式可以减少大量的人工操作,并且能够用于实现自动化工业生产。复合材料热隔膜预成型是一个使预浸料叠层变形的复杂过程,本文对带曲率C型梁的预成型过程进行仿真分析,首先通过试验得到预浸料铺层间摩擦系数,然后对湿态预浸料的力学性能进行测试。利用测试得到参数,采用有限元方法对C型梁预成型过程中铺层间的滑移进行模拟得到了铺层变形后的褶皱缺陷。通过专用的热隔膜成型设备对C型梁预成型进行试验研究,将试验结果与仿真结果进行对比分析,验证了预成型仿真手段的可行性,为后续热隔膜预成型过程中的参数优化提供指导。     

多因素作用下自动铺丝预浸料黏性变化规律

自动铺丝工艺是一种先进复合材料低成本、自动化成型制造工艺,其通常应用于制造飞机机身、S型进气道等大曲率复合材料构件。铺丝过程中,预浸料丝束黏性对铺丝产品最终质量有较大影响。一方面,丝束黏性不能过低,以保证预浸料之间顺利贴合。另一方面,丝束黏性也不能过高,以便于铺层失败时进行修改。目前,预浸料黏性评价方法以90°剥离试验与180°剥离试验为主,其主要针对自动铺带工艺中较宽的预浸带。前期初步试验表明,采用单丝束剥离试验法检测自动铺丝工艺中预浸料黏性时,数据会产生较大波动,无法满足相关检测要求。有鉴于此,本文首先建立自动铺丝预浸料黏性的检测准则,提出采用两丝束180°剥离试验检测预浸料黏性,然后基于该准则研究铺放压力、铺放速度、铺放温度、老化时间影响下丝束黏性的变化规律。     

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.     

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。     

Inorganic/organic nanocomposite coatings: The next step in coating performance

Inorganic/organic hybrid materials have considerable promise and are beginning to become a major area of research for many coating usages, including abrasion and corrosion resistance. Our primary approach is to prepare the inorganic phase in situ within the film formation process of the organic phase. The inorganic phase is introduced via sol-gel chemistry into a thermosetting organic phase. By this method, the size, periodicity, spatial positioning, and density of the inorganic phase can be controlled. An important aspect of the inorganic/organic hybrid materials is the coupling agent. The initial task of the coupling agent is to provide uniform mixing of the oligomeric organic phase with the sol-gel precursors, which are otherwise immiscible. UV-curable inorganic/organic hybrid systems have the advantages of a rapid cure and the ability to be used on heat sensitive substrates such as molded plastics. Also, it is possible to have better control of the growth of the inorganic phase using UV curing. It is our ultimate goal to completely separate the curing of inorganic and organic phases to gain complete control over the morphology, and hence optimization of “all” the coating properties. Thus far, it has been found that concomitant UV curing of the inorganic and organic phases using titanium sol-gel precursors afforded nanocomposite coatings which completely block the substrate from UV light while maintaining a transparent to visible light. Also, it has been found that the morphology of the inorganic phase is highly dependent on the concentration and reactivity of the coupling agent. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004, in Chicago, IL.