熔融树脂法(干法)制备单向纤维预浸带的工艺研究

本文通过对单向玻璃纤维预浸带的浸透性、含胶量及其厚度研究,论述了环氧648-BF₃MEA体系熔融树脂法制备单向预浸带工艺的可行性,并通过模拟浸带装置,确定了相应工艺参数及其主要工艺参数的质量控制方法。      

热熔挤出法制备PEK—C／碳纤维预浸带研究

本工作设计、装配了一条实验室用热熔挤出法制备耐高温热塑性树脂基连续单向碳纤维预浸带的装置,并对PEK—C/碳纤维预浸带的制备工艺进行了研究。     

流延法制备短纤维增强玻璃陶瓷基复合材料

研究了短纤维增强玻璃陶瓷基复合材料制备工艺中的短纤维分散和单向纤维预浸片制备。结果表明: 在聚乙稀醇水溶液与乙二醇的混合分散介质中, 采用搅拌法可以得到短纤维的均匀分散, 分散介质的触变性对于均匀分散体系的获得与保持是十分必要的; 流延法有利于控制短纤维预浸片中纤维的取向。单向预浸片热压获得了高强韧性的复合材料试样。      

PEEK基体热塑性树脂基复合材料的研究

介绍了热塑性树脂基复合材料用ＰＥＥＫ树脂的性能，静电粉末法制备热塑性树脂预浸料的设备和工艺，用该工艺制备的预浸料规格和性能以及ＡＳ４Ｃ单向织物／ＰＥＥＫ复合材料的力学性能，韧性，耐环境性能，同时还介绍了将这种材料用于宇航工业而进行的基础研究工作。     

碳纤维/环氧树脂复合材料-铝合金层合板深拉成型特性

碳纤维增强树脂复合材料（Carbon fiber reinforced plastic,CFRP）因其轻质高强的特点,越来越多地应用到汽车轻量化设计和制造中。为研究CFRP板件及CFRP-Al层合板深拉成型影响因素,加速CFRP零部件产业化进程,本文通过DSC测试分析了CFRP预浸料的固化放热过程,以此为依据,用热压罐制备了不同后固化温度下成型的CFRP板材及单向、编织两种预浸带铺层的CFRP-Al层合板,用Inspekt table 100材料试验机对上述两种板材分别做了深拉试验。考虑到提高制备效率,用打磨、打磨+涂覆硅烷偶联剂、阳极氧化+涂覆硅烷偶联剂三种方式对铝合金板进行表面处理,不经热压罐固化成型,直接和正交对称铺层的单向预浸带一起在Inspekt table 100材料试验机的环境箱中混合温深拉,固化成形。并通过金相显微镜、SEM进行显微组织观察,验证后固化温度、深拉环境温度、预浸带的种类对CFRP板材及CFRP-Al层合板深拉成型性能的影响及铝合金板表面处理方式对CFRP叠层预浸带、铝合金板材混合温深拉成型性能的影响。结果表明,适当降低后固化温度、提高深拉环境温度有利于板材二次深拉成型。编织预浸带较单向预浸带能更好地承受压力,深拉成型质量更优。阳极氧化+涂覆硅烷偶联剂的表面处理方式一方面能在铝合金板材表面形成致密、均匀的微孔,另一方面硅烷偶联剂能很好地促进铝合金板材和CFRP的界面结合,有利于深拉成型。      

氧化石墨烯/炭纤维/环氧树脂基复合材料的制备及其层间剪切性能（英文）

利用预浸料技术热压工艺,制备了氧化石墨烯改性的炭纤维环氧树脂基复合材料。为获得更好的分散效果及加工性能,选用四氢呋喃作为溶剂来分散氧化石墨烯。结果显示:含有氧化石墨烯的混合胶液体系可稳定3 h左右,满足预浸料制备工艺要求;制得的复合材料单向层板层间剪切强度(ILSS)有较大提高,当氧化石墨烯含量为0.10%时,其达到96.14 MPa,与空白样板相比提高了约8.05%,玻璃化转变温度升高近5℃。断面形貌分析表明,上述显著提高可能是由于氧化石墨烯的加入使得环氧树脂增韧以及炭纤维复合材料的界面得到较大的改善所致。     

用β射线技术在线监测复合材料预浸带树脂含量

建立＾１４Ｃ弱源β射线监测仪，对热熔预浸工艺生产预浸带用涂胶离型纸的树脂含量进行了动态测量，并与重量法间断测量结果进行了比较，研究表明，β射线透过涂胶纸强度和原强度之比（Ｉ／Ｉ０）与树脂含量具有良好的对应关系，该仪器用于预浸树脂含量在线检测是可行的。     

零吸胶炭纤维增强高温固化环氧复合材料预浸料研制

针对大尺寸、大厚度复合材料构件对“零吸胶”预浸料的需求,对低树脂含量炭纤维增强高温固化环氧复合材料预浸料进行了研制,并对预浸料的外观和物理性能、复合材料基本力学性能及成型工艺性能进行了研究.通过对预浸料制造工艺参数的优化,研制出了低树脂含量炭纤维增强高温固化环氧复合材料预浸料,其外观和物理性能满足要求;采用低树脂含量预...     

热塑性预浸带缠绕工艺参数及加热方式对成型质量及内应力的影响

采用热塑性预浸料带APC-2/AS4 进行了热芯和火焰两种方法的缠绕研究, 分析了两种方法成型时预浸料带的温度2时间过程和两种方法下工艺参数对成型质量及内应力的影响。结果显示: 热芯缠绕时制件的厚度受芯模温度限制, 而火焰缠绕则不受限制。热芯缠绕时, 缠绕张力和预浸料带的树脂含量是影响制件质量的主要因素。      

纤维增强热塑性树脂预浸料的制备工艺及研究进展

热塑性复合材料因冲击韧性高、环境适应性强、可回收利用等优点,被广泛应用于汽车制造、航空航天、国防军工等领域。但因热塑性树脂加热熔融后较高的黏度使其很难与纤维充分浸渍。预浸料作为制造复合材料的中间材料,现阶段制备工艺已相对成熟,预浸料中纤维已被树脂浸润,因此通过预浸料制备的复合材料孔隙率较低。本文介绍了现阶段常用的热塑性预浸料制备方法及各自的优缺点,包括溶液浸渍法、熔融浸渍法、粉末浸渍法、薄膜叠层法、纤维混杂法以及反应链增长浸渍法。阐述了热塑性树脂熔体浸润纤维的浸渍机理,对浸渍机理的部分研究成果进行了概括。概述了浸渍温度、浸渍压力和牵引速率对预浸带性能的影响。最后指出了国内预浸料生产中存在的主要问题,未来可采用多学科结合、纤维树脂改性、对浸渍过程进行计算机模拟等方法促进热塑性预浸带的产业化发展。     

Beta ray monitoring technique for control of resin content in continuous fibre prepreg materials

Abstract

A beta ray monitoring technique has been developed to measure the resin content during the manufacture of preimpregnated fibre (prepreg) unidirectional tapes by a solution impregnation process. A series of calibration relationships have been obtained for aramid, carbon and glass fibre reinforced epoxy prepreg tapes, and the effect of variation of the fibre areal weight on measuring accuracy has been analysed. Good agreements with resin content have been demonstrated using the beta ray system and conventional solvent extraction method. Moreover, online control of the resin content has been carried out by adjusting the concentration of resin in the impregnation bath.     

On-line consolidation of thermoplastic composites using laser scanning

A novel technique to process thermoplastic composites by laser-assisted tape winding has been developed and evaluated. Previous investigations were limited to a stationary beam and consolidation of narrow prepreg tapes. The technology was extended to process wider prepreg tapes using a galvanometer-based scanning system. The energy distribution along the consolidation line is affected by the triggering signal used to position the scanning mirror. This distribution is predicted using a geometrical model and the results are confirmed experimentally with imprints of the scanned beam in Plexiglas. It was found that the most homogenous heating of the surface is achieved if a triangular triggering signal is used. Density and short beam shear tests are used to evaluate the bond quality that can be achieved using the beam scanning system in comparison to parts fabricated with a stationary beam. Tests have been performed on parts processed with different laser power settings and scanning frequencies. The shear strength increases with increasing laser power to an optimum value after which it decreases due to the degradation of the thermoplastic matrix. The scanning frequency in contrast had no influence on the shear strength. The possibility to process wider tapes using the scanning system was demonstrated by consolidating a one-inch wide PPS/Carbon prepreg tape.     

A process model for the compaction and saturation of partially impregnated thermoset prepreg tapes

Automated manufacturing of composite materials is key to reducing cost and improving consistency in part quality. Modeling of manufacturing processes can identify influential material, geometric, and process variables, while providing a framework for their optimization and control. A process model has been formulated to describe the compaction and saturation of partially impregnated thermoset prepreg tapes during their placement, using a roller compaction and vacuum consolidation. The roles of various parameters that characterize the initial prepreg tape state and the final prepreg tape state are investigated. The model yields the degree of resin saturation in the tape with changes in its thickness after being compacted, due to an external pressure. The results estimate the degree of dry fiber region within the tape, which can provide vacuum pathways for air or volatile removal before consolidation and cure. The model can be adapted for different material constitutive relationships of tape compaction and saturation.     

Residual stress distribution in carbon fibre/thermoplastic matrix pre-impregnated composite tapes

The distribution of residual strain in carbon fibre (P75) reinforced thermo-plastic (polyetheretherketone, PEEK) composites has been studied by monitoring the Raman frequencies of the embedded carbon fibres at the microscopic level. The average longitudinal strain in the fibre measured in a 100 mm² section of a P75/PEEK prepreg was found to be compressive and comparable in magnitude to residual strain values computed analytically. The combined effects of differential thermal expansion of the two materials, differences in fibre size and in the thickness of resin layer, are offered as likely explanations for the incurred variations in the Raman frequency values and the considerable spread of the fibre Raman frequency distribution in the prepreg tape. Finally, it is demonstrated that the previously reported high values of apparent compressive strain in similar composite tapes by means of Raman spectroscopy were artefacts of the experimental procedure.     

Robust design of microfactory elements with high stiffness and high damping characteristics using foam-composite sandwich structures

In order to enhance structural robustness of microfactory machine elements the foam-composite sandwich structure was introduced. Unidirectional carbon/epoxy prepreg as skin materials and PVC foams as core materials were used to construct the sandwich structures. The existing aluminum column and the column block were replaced by foam-composite sandwich structures with appropriate rib geometries and configurations. The stacking sequences and rib configurations were determined by finite element analyses. The damping capacity was also investigated by vibration tests preparing beam type composite and foam-composite sandwich specimens with various stacking sequences and thickness ratios. The prototype of the column and the column block were fabricated using proper moulds and processes and finally, the system performances such as dynamic robustness and damping capacity were verified by comparison with the existing aluminum system.     

环保型捆扎机送胶、烫合机构的设计

捆扎机是目前应用最广的打包机器,它采用的聚丙烯塑料带难以降解,污染环境。采用纸带捆扎能在达到捆扎要求的前提下避免聚丙烯塑料带存在的诸多问题。通过对机械式半自动捆扎机关键机构的研究,改进了烫头及烫头凸轮,设计增加了送胶机构,并对关键机构进行了仿真和机构运动分析,说明了设计的可行性。     

Void formation in composite prepregs – Effect of dissolved moisture

Void formation as a function of resin moisture content was investigated to better understand and control process defects in composite parts made from prepreg. In this study, uncured prepreg was conditioned at 70%, 80% and 90% relative humidity and at 35 °C. Conditioned prepreg was laid up into quasi-isotropic laminates and cured using vacuum bag only (VBO) processing (low-pressure), and autoclave processing. Moisture uptake in the resin was measured using coulometric Fischer titration. Void content was measured by image analysis of polished sections of cured laminates. Void fractions increased substantially with increasing moisture content in VBO processed laminates, while autoclave-processed parts remained void-free. Experimental results were consistent with trends predicted using a diffusion-based analytical model. The findings are discussed in the context of causes of voids in prepreg composites.     

Investigation on Effect of Magnetic Field Dependency Coefficient of Critical Current Density on the AC Magnetizing Loss in HTS Tapes Exposed to External Field

High-temperature superconducting (HTS) technology is the most promising, advanced, and beneficial technological developments of the last two decades in terms of fabricating more efficient, compact, and reliable electrical power apparatus. The second-generation HTS wires are now quite competitive with traditional conductors from the cost point of view. In addition, they are of high interest in electrical machine manufacturing due to their unique merits such as high current density, high magnetic field, and low loss. The most significant issue for any superconducting devices which work with alternating current or magnetic field is the AC loss of the HTS tapes. Since HTS tapes are always exposed to an external magnetic field in electrical machine applications, it is vital to consider the effect of this external field on their AC magnetizing (ACMG) loss. It is well-known that external magnetic field decreases the current carrying capability of the wire. In real life, critical current density of HTS tapes is dependent to magnetic field but this dependency sometime was not considered in modeling stage in order to make it faster and simple. In this paper, the electromagnetic properties of HTS tapes for use in superconducting electric machines have been investigated with a particular focus on the ACMG loss of YBCO tapes. For this purpose, a two-dimensional finite element model has been implemented based on the H formulation in order to study the effect of dependency of critical current density to magnetic field on the variation of ACMG loss. The modeling results will be helpful for electrical machine designers to have a better understanding about this effect and have a more accurate estimate of ACMG loss in design stage.