接头尺寸对玻璃纤维/热塑性树脂复合材料机械连接性能的影响接头尺寸对玻璃纤维/热塑性树脂复合材料机械连接性能的影响

对玻璃纤维/聚酰胺（GF/PA）、玻璃纤维/聚甲醛（GF/POM）、玻璃纤维/聚丙烯（GF/PP）这三种玻璃纤维增强热塑性树脂基复合材料进行机械连接试样的常规拉伸试验,以及低周疲劳拉伸试验,并对疲劳前后的试样断裂面进行SEM观察,研究了接头尺寸（宽径比w/d （试样宽度/开孔直径）和端径比e/d （试样端距/开孔直径））对机械连接件破坏载荷和破坏模式的影响。实验结果表明:玻璃纤维增强纤热塑性树脂复合材料机械连接件的承载能力在一定的宽径比时会随着e/d的增加而增加,当w/d≥3、e/d≥2时趋于稳定;破坏模式以拉伸破坏为主;低周疲劳拉伸对GF/POM和GF/PA机械连接试样拉伸强度产生一定的影响,而对GF/PP的拉伸强度无明显影响,低周疲劳拉伸对玻璃纤维增强热塑性树脂复合材料机械连接试样的破坏模式没有影响。SEM观察显示,随着疲劳载荷水平的增加,GF/POM和GF/PA的断裂面上被抽拔纤维数量增加,而GF/PP断裂面纤维与基体的存在状态无明显变化。      

紫外辐照对玻纤增强树脂基复合材料冲蚀性能的影响

为了探讨紫外老化对玻璃纤维增强环氧乙烯基酯树脂基复合材料冲蚀性能的影响,对玻璃纤维增强环氧乙烯基酯树脂基复合材料进行人工紫外加速老化试验,并对不同老化时间下试样进行冲蚀;采用扫描电镜、红外光谱仪及差式扫描仪研究了老化前后材料表面形貌、化学结构以及玻璃化转变温度的变化,并分析了不同老化时间对试样巴氏硬度、质量损失率及冲蚀失重率的影响.结果表明：随着老化时间的增加试样表面发黄现象逐渐加剧,并出现树脂基体的开裂、剥离及纤维暴露;紫外老化7 d后试样的抗冲蚀性能提升了5.3%、巴氏硬度上升3%,但老化56 d后试样抗冲蚀性能下降了15.1%、巴氏硬度下降14.6%;老化56 d后试样玻璃化转变温度上升9.3 ℃.紫外老化是一个由表及里的过程,首先造成表层树脂性能的下降;紫外老化引起树脂基体的分解、玻璃纤维与树脂基体界面的脱黏、树脂基体的脆化,进而导致材料抗冲蚀性能的下降.     

纤维增强树脂基复合材料的空泡腐蚀试验研究

本文利用磁致伸缩试验实验法对几种纤维增强树脂基复合材料(FRP)试样在水中耐空泡腐蚀的性能进行研究。研究了材料失重率与空泡腐蚀时间、质量损失与空泡腐蚀时间的关系及纤维对试样空蚀效果的影响,实验表明控制空泡腐蚀条件不变,可以通过材料的质量损失随时间关系,来判断材料的抗空泡腐蚀性。几种增强材料对复合材料试样的抗空泡腐蚀效果:玻璃纤维芳纶纤维玻璃纤维带状编织物碳纤维带状编织物。     

玻璃纤维增强树脂基复合材料的介电特性

本文介绍了玻璃纤维增强树脂基复合材料作为电介质材料的特点及影响因素。并介绍了低介电性能环氧树脂/玻璃纤维复合材料的研究现状以及PTFE、氰酸酯树脂等高性能透波复合材料的研究进展。     

UV光固化玻璃纤维布/EP-PBMA树脂复合材料的力学性能

设计了光热共引发环氧树脂-聚甲基丙烯酸丁酯(EP-PBMA)树脂,并制备了UV光固化玻璃纤维布增强EP-PBMA树脂基复合材料,研究了不同EP与PBMA质量比的玻璃纤维布/EP-PBMA复合材料在不同加载速率下的拉伸力学性能。结果表明: 玻璃纤维布/EP-PBMA复合材料具有明显的应变率效应;随着加载速率增大,复合材料的拉伸强度和弹性模量呈增大趋势;EP-PBMA树脂基体的组成对应变率效应有明显的影响;玻璃纤维布/EP-PBMA复合材料与纯EP基复合材料相比,在较低的加载速率下具有更高的拉伸强度,但当加载速率达到50 mm/min时拉伸强度较低。     

包装箱用混杂纤维复合材料的设计

目的 研究混杂纤维复合材料在静载荷作用和拉-拉疲劳载荷条件下的力学性能及其在包装箱等领域的应用。方法 采用树脂转移模塑成型工艺制备5种包装箱用混杂纤维复合材料,并对试样进行拉伸性能和拉-拉疲劳性能测试。结果 纯C试样的拉伸强度高于C/G层内和C/G层间试样;在相同的铺层和织布方式下,C/G层内试样的拉伸强度高于C/G层间试样;纯G试样的塑性明显优于C/G层内和C/G层间试样,C/G层内试样的断裂伸长率高于C/G层间试样;C/G层内试样具有混杂正效应,可保证在具有较高强度的同时具备良好塑性。玻璃纤维在提高复合材料料板疲劳寿命上的作用要高于芳纶纤维,前者的刚度退化会低于后者,且碳纤维和玻璃纤维的层内混杂方式要优于层间混杂,层间混杂在复合材料抵抗疲劳损伤时具有正混杂效应。     

引发体系对乙烯基酯树脂固化行为及厚截面层压板力学性能的影响

选取预促进型乙烯基酯树脂(VE)为树脂基体,过氧化甲乙酮、过氧化异丙苯、过氧化乙酰丙酮及其复配体系作引发剂。通过差示扫描量热法(DSC)及凝胶试验研究了不同引发体系下树脂的固化行为。采用真空辅助树脂传递模塑工艺(VARTM)制备了乙烯基酯树脂/玻璃纤维复合材料层压板,通过复合材料的弯曲性能及切割面状态研究,筛选了适用于高温下厚截面乙烯基酯树脂/玻璃纤维复合材料层压板成型的引发体系。结果显示,引发剂类型及用量均影响树脂体系的固化行为,对于高温下厚截面复合材料层压板的成型,需选用合适用量的低放热引发剂;通过室温放置1个月的后固化措施,将显著提高厚截面乙烯基酯树脂/玻璃纤维复合材料层压板的弯曲性能。     

碳纤维-玻璃纤维层内混杂单向增强环氧树脂复合材料拉伸性能

采用不同混杂比的碳纤维-玻璃纤维层内经向混编单轴向织物制备了混杂纤维增强环氧树脂复合材料, 研究了不同混杂结构和不同混杂比的碳纤维-玻璃纤维/环氧树脂复合材料拉伸性能的变化及破坏形式。0°拉伸结果表明:同种混杂织物的不同混杂结构中, 碳纤维相对集中的完全对齐结构强度最高, 不同混杂比织物的完全对齐结构强度相当;碳纤维-玻璃纤维/环氧树脂复合材料的模量遵循混合定律。90°拉伸结果表明:纤维与树脂间的界面结合强度为碳纤维/树脂>玻璃纤维/树脂, 碳纤维-玻璃纤维/环氧树脂复合材料的强度、模量与材料厚度方向上界面的不同形式(单一或交替界面、碳纤维或玻璃纤维的分布位置等)有关, 与碳纤维的含量基本无关。      

GF/VE复合材料的等温固化动力学模型

采用DSC差示扫描量热分析仪研究了玻璃纤维/乙烯基酯树脂复合材料等温固化过程及升温后固化过程,建立了新的自催化模型来模拟其等温固化过程。结果表明,新建的模型很好地模拟了玻璃纤维/乙烯基酯树脂复合材料等温固化过程,尤其适合于复合材料的高温固化过程模拟。     

空隙率对喷气混纤纱复合材料力学性能的影响

利用玻璃纤维/聚丙烯喷气混纤纱(50∶50 w t% ) , 在热压机上制作单向玻璃纤维/聚丙烯复合材料。按照A STM D792 标准, 测试各试样中的空隙率, 并利用三点弯曲试验在DCS500 试验机上测试试样的弯曲性能。试验结果得到空隙率与喷气混纤纱复合材料弯曲性能之间为负指数关系, 且对不同的弯曲指标其关系也不相同。      

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.