三维夹芯复合材料冲击损伤后弯曲性能研究

采用手糊成型工艺将环氧树脂与三维机织夹芯织物及玻纤平纹织物复合,制成三维夹芯复合材料,并采用不同的冲击高度对其进行低速冲击试验。利用Instron 5969H型万能材料试验机对经过低速冲击试验的三维夹芯复合材料的弯曲性能进行测试,分析冲击高度对三维夹芯复合材料弯曲性能的影响。结果表明:同种三维夹芯复合材料的弯曲性能与冲击高度呈负相关;相同冲击高度下,同种三维夹芯复合材料的经向剩余弯曲强度明显低于其纬向剩余弯曲强度。     

三维多向编织复合材料T型梁抗弯应力分析

针对三维多向编织复合材料结构件承载细观结构优化设计的问题,以三维编织复合材料T型梁为对象,对其抗弯性能进行模拟分析。基于细观结构单胞模型,采用刚度体积平均法计算具有不同编织角的三维四向、五向和六向编织复合材料的弹性常数;利用有限元软件Patran/Nastran计算T型梁承受弯曲载荷的应力与应变,分析纤维束交织结构和细观结构参数对T型梁抗弯性能的影响。结果表明,纤维体积含量一定时,三维六向较三维四向、五向编织复合材料的弹性性能更接近各向同性,同时选择比较大的编织角,可提高T型梁抗弯的承载能力。此方法可为异型三维编织复合材料构件细观结构的选型与参数设计可供参考。     

三维多向编织复合材料T型梁抗弯应力分析

 针对三维多向编织复合材料结构件承载细观结构优化设计的问题,以三维编织复合材料T型梁为对象,对其抗弯性能进行模拟分析。基于细观结构单胞模型,采用刚度体积平均法计算具有不同编织角的三维四向、五向和六向编织复合材料的弹性常数;利用有限元软件Patran/Nastran计算T型梁承受弯曲载荷的应力与应变,分析纤维束交织结构和细观结构参数对T型梁抗弯性能的影响。结果表明,纤维体积含量一定时,三维六向较三维四向、五向编织复合材料的弹性性能更接近各向同性,同时选择比较大的编织角,可提高T型梁抗弯的承载能力。此方法可为异型三维编织复合材料构件细观结构的选型与参数设计可供参考。     

单元对船用复合材料板架数值模拟精度的影响

针对船用复合材料板架在横向弯曲载荷作用下的有限元仿真计算精度未得验证的问题,文章基于abaqus对某帽型梁复合材料板架有限元数值模拟,对比了多种单元模拟下的静强度仿真结果和试验结果,并分析了帽型梁中的填充泡沫与帽型梁帽缘对整体结构的强度和刚度影响,其中实体单元模拟的计算结果与试验结果的相对误差低于9%,壳-壳单元建模法相对误差小于15%,壳-梁单元建模法相对误差在20%以内,有无填充泡沫和帽缘之间的数值模拟结果相对误差低于5%,结果表明在船用复合材料板架弹性变形范围内,可以按照工程误差许可选择不同的单元来数值模拟,整体结构建模时填充泡沫和帽缘可以忽略。     

玻纤/芳纶针织物夹芯复合材料的制备与弯曲性能研究

以满针罗纹、双反面及纬平针芳纶针织物为芯层,以单向玻璃纤维织物为外层制备层合结构的增强体,以环氧树脂和固化剂混合胶液为基体,基于真空辅助树脂传递模塑成型工艺(VARTM)成功制备出玻纤/芳纶针织物夹芯复合材料试样.研究了3种玻纤/芳纶针织物夹芯复合材料试样的弯曲性能.结果 表明:针织物的结构对复合材料的弯曲性能有重要影响,提高针织物受力方向上纱线的数量和强度均可增强复合材料的弯曲性能.     

等离子体-硅烷偶联剂改性芳纶纬平针织复合材料的力学性能研究

采用等离子体联合不同质量分数的硅烷偶联剂溶液对芳纶纬平针织物进行改性,再利用真空辅助树脂传递模塑成型(VARTM)工艺制备未改性及改性芳纶纬平针织复合材料。通过测试和分析芳纶纬平针织复合材料的拉伸、弯曲、压缩和冲击性能发现：改性芳纶纬平针织复合材料的拉伸、弯曲、压缩和冲击性能较未改性芳纶纬平针织复合材料的都有所改善;随着硅烷偶联剂质量分数的增加,改性芳纶纬平针织复合材料承受的最大拉伸载荷、最大弯曲载荷、最大压缩载荷和最大冲击载荷呈现先增加后减小的趋势,其中等离子体-硅烷偶联剂(w_{硅烷偶联剂}=1.5%)改性芳纶纬平针织复合材料各项性能改善最明显,其能承受的最大拉伸载荷、最大弯曲载荷、最大压缩载荷和最大冲击载荷较未改性芳纶纬平针织复合材料的分别提高了32.73%、38.03%、24.83%和35.10%。     

碳纤维/环氧树脂基中空夹芯复合材料压缩性能的有限元法研究

在已有研究的基础上,利用有限元软件ANSYS Workbench,建立了三维中空夹芯复合材料结构模型,进行三维中空夹芯复合材料的压缩性能研究。利用该模型,探讨了材料在2 mm压缩位移载荷作用下纤维、树脂和复合材料的应力、应变分布。结果表明:三维中空夹芯复合材料在压缩载荷作用下,芯材交叉处应力最大,最容易发生压缩破坏;上下面板应力最小,最不容易发生压缩破坏;复合材料在承受压缩载荷作用时,纤维起主要承载作用,树脂起次要作用;材料的破坏模式主要为树脂破裂。     

芯纱刚性对包芯纱的包芯性及织物悬垂性的影响

在环锭细纱机上试生产了几种不同芯纱的毛型包芯纱，并试织了相对应的织物。通过测试这些毛型包芯纱的不同芯纱的抗弯刚度，找出了芯纱抗弯曲性能对芯纱包覆效果和对织物悬垂性能的影响。研究了芯纱抗弯曲刚度与芯纱包覆效果和织物悬垂性的关系。     

石墨烯黏胶纤维机织物的功能改性研究

制备同规格的普通黏胶纤维机织物、石墨烯黏胶纤维机织物及不同不锈钢丝质量分数的石墨烯黏胶纤维/不锈钢丝机织物,对比它们的导电、防电磁辐射、防紫外线、抗静电、力学(拉伸、弯曲、耐磨)及透气等性能。结果表明:普通黏胶纤维经石墨烯改进后,所制成的石墨烯黏胶纤维机织物的导电、防电磁辐射、防紫外线、抗静电、力学(拉伸、弯曲、耐磨)等性能都有所改善,其中防紫外线与耐磨性能提高显著,透气性能下降明显;石墨烯黏胶纤维/不锈钢丝机织物的导电、防电磁辐射、防紫外线和抗静电、经向拉伸断裂强力、纬向抗弯刚度、透气性能都优于石墨烯黏胶纤维机织物,纬向拉伸断裂强力、经纬向拉伸断裂伸长率、经向抗弯刚度及耐磨性能不及石墨烯黏胶纤维机织物;随着不锈钢丝质量分数在7.0%~20.0%范围内的增加,石墨烯黏胶纤维/不锈钢丝机织物的导电、防紫外线、抗静电、经向拉伸断裂强力、纬向抗弯刚度及透气性能增强,纬向拉伸断裂强力、经纬向拉伸断裂伸长率、经向抗弯刚度、耐磨性能减小,不锈钢丝质量分数变化对防电磁辐射性能影响较小。当不锈钢丝质量分数为7.0%时,石墨烯黏胶纤维/不锈钢丝机织物的综合性能最佳。     

芯材高度对整体中空复合材料力学性能的影响

整体中空复合材料是由纤维连续织造呈整体中空结构的新型夹芯材料,具有质轻、高强、高模、可设计等特点.研究了整体中空复合材料在拉伸、压缩、剪切、弯曲等载荷作用下的力学特性,重点分析了芯材高度对材料力学性能的影响.结果表明:整体中空复合材料的侧拉、弯曲破坏模式为脆性破坏,侧压为芯材失稳破坏,剪切为"先剪后拉"破坏模式;随芯材高度的增加,材料的侧拉、侧压和弯曲强度增加,剪切强度降低.研究结果为该类材料的结构优化设计和性能分析奠定了基础.     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press