复合材料叶片结构设计中的几个关键问题探讨

风力发电技术作为新兴技术,欧美一些国家已发展到相当高的水平,我国风力发电近些年也发展迅猛。风力发电的关键技术之一是风力机复合材料叶片的设计与研制,涉及到空气动力学、结构力学、复合材料力学及成型工艺等。本文着重探讨复合材料叶片的结构设计中几个关键的问题,在广泛分析和研究国内外复合材料结构设计现有技术基础上,并结合实际的研究经验,对复合材料叶片结构设计中的材料选择、载荷工况、结构选型、铺层设计以及力学分析等关键环节进行探讨和分析,并给出可行的意见。     

1.5MW风机叶片模具加热工艺研究与技术创新

在大型风力机复合材料叶片的生产过程中,模具起着至关重要的作用.为了满足风力机复合材料叶片生产的关键工艺要求,采用新型的复合材料叶片模具作为核心工艺装备成为必备条件.通过对复合材料叶片模具的制作工艺研究和技术创新,使得新型模具完全满足了大型风机复合材料叶片生产的所有工艺需求.其中,模具的加热方式采用水(油)加热或电加热,要求所产生的热量可以均匀地传递到模具复合材料型面上,并达到产品叶片固化所需的温度.     

风电市场:纤维增强材料的机遇

1全球概况风电是发展最快的可再生能源,也是复合材料行业一个迅速增长的市场。据报道,在2005年和2006年,全球风电装机容量的增长率均超过25%,在2006年底全球风电装机容量超过70 000 MW。一些最大的风力发电机已超过5 MW,甚至10MW的巨型风力机也正在研制之中。而目前,绝大多数风力机的转子叶片、大多数机舱罩和整流罩都采用复合材料制造,且风力机的规格越来越大,一个大型的海上风力机叶片重量可能达到20t,所以,这些风力机部件为复合材料创造了一个非常强大的市场。     

风电叶片顶部可制成“风筝”

风力发电叶片顶部可制成"风筝"。以后的风力发电设备可能不再是现在一排排矗立在海边的大型转动的风机,而是一个个飘在空中的风筝。29日,英国威尔士政府现场展示部分投资项目吸引中国企业参与合作,其中一项风筝风力发电项目引起大家注意。它就是取下传统风力发电叶片顶部,做成一个"风筝"放飞到高处以获取风能,呈圆形运动。与传统风力机相比,风筝发电节能40%到60%。预计2017年将生产出第一台发电     

用于风力机叶片的先进环氧技术

环氧复合材料在许多要求高的应用中(比如风力机叶片部件)提供了高性能和已被证实的可靠性。在发展对风力机叶片复合材料破坏的基本认识,以及提供新颖的方案来同时解决破坏和生产率问题上,Dow公司取得了显著进展。     

风机叶片用玻璃纤维复合材料研究概述

介绍了风机叶片结构设计,叶片动力学分析,风机叶片性能有限元数值模拟,叶片疲劳及渐进损伤分析等领域国内外复合材料风机叶片研究内容.针对传统多轴向经编织物增强复合材料易损伤失效的现状,提出应用1种新型三维机织织物制备复合材料风机叶片,提高叶片强度及抗分层失效问题.为此,提出1种三维结构织物增强的复合材料用于风机叶片.     

风电叶片雷击防护的研究进展

风力发电是一种清洁能源,近年来受到全球范围的关注。随着陆上风力发电场趋于饱和,风力发电逐渐向海上扩张。海上风电虽与陆上风电有所不同,但雷电袭击对于海陆风电力发电场来说,都是威胁其运行安全的严重问题。风电叶片作为风电机组的重要组成部件之一,其受雷击后会导致风机停运,带来严重的经济损失。叶片的雷击防护已引起人们的重视,成为风电领域和防雷领域的热点问题。本文阐述了风电叶片防雷系统的现状和问题,风电叶片雷击防护的研究进展,并结合复合材料雷电实验的研究成果,为海上风电叶片防雷系统的研究提供新思路和新方向。     

国内风机技术趋势:大叶片及一站式解决方案

成立6年的Blade Dynamics公司,正在开发一种新技术用以制造全球最大的风机叶片,其号称长度能达到100米,目前世界最大的叶片不过只有75米长。风机叶片是风能技术进步的关键核心风力机部件,其良好的设计、可靠的质量和优越的性能是保证机组正常稳定运行的决定因素。而更长的叶片也可以配合大功率风机的制造,时下这种趋势越来越明显。除此之外,在风机行业中,还需要攻克高端零部件制造、如何提高单个风机及整个风电场     

大型风力机复合材料叶片技术及进展

本文介绍了大型风力机复合材料叶片技术现状,叙述叶片气动、结构、工艺等关键技术.随着风力机组向大容量方向发展及海上风能的开发利用,将对风力机复合材料叶片的设计、材料及制造提出了挑战.     

2MW风机复合材料叶片材料及工艺研究

风力机在工作过程中,风机叶片要承受强大的风载荷、气体冲刷、砂石粒子冲击、紫外线照射等外界作用.为了提高复合材料叶片的栽荷、耐腐蚀和耐冲刷等性能,必须对树脂基体系统进行精心设计和改进,采用性能优异的环氧树脂,改善玻璃纤维/树脂界面的粘结性能,提高叶片的承载能力,扩大玻璃纤维在大型叶片中的应用范围.通过对新型环氧树脂的研究和对传统叶片工艺的创新,研究结果表明复合材料叶片可以达到在恶劣工作环境中长期使用的性能.     

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.     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。