采用薄膜传感器的树脂基复合材料热压罐工艺密实压力测试方法

针对树脂基复合材料层板热压罐成型工艺,采用薄膜压力传感器建立了密实压力在线测试系统,用于监测成型过程中复合材料所受密实压力的大小和分布。研究了密实压力测试系统在热压罐工艺条件下的适用性,在此基础上以该系统为测试手段,研究了热压罐工艺下L形碳纤维/环氧树脂复合材料层板的密实压力变化规律及模具形式的影响。结果表明: 所建立的密实压力测试系统具有较高的准确性和动态响应性,能够测试高温条件及曲面位置的密实压力,满足复合材料热压罐成型过程中密实压力的在线测试要求; L形复合材料层板成型过程中拐角区与平板区的密实压力随热压罐压力增大而增加,但增加速度和最终大小不同,阳模成型时拐角区密实压力高于平板区,阴模成型时拐角区密实压力小于平板区和外加压力,表明曲面结构与平板结构的密实行为具有差异性。     

复合材料热压罐的研制

复合材料热压罐的研制王金秀董秀琴金京华郎业方（北京航空材料研究院）热压罐是复合材料成型的关键设备，近年来，随着复合材料专业的发展和应用领域的拓宽，复合材料制件向着高精度、大尺寸的方向发展，这就对成型设备提出了更高的要求。为了满足军民品应用领域的迫切要...     

基于温度曲线优化的复合材料热压罐固化时间与固化质量协同控制

温度曲线是复合材料热压罐成型的重要工艺参数,对成型时间和构件的固化质量有着直接影响.对温度曲线进行合理的优化设计,可以实现对固化时间与固化质量的协同控制.本工作基于复合材料固化成型模拟计算方法,针对复合材料C形构件开展固化成型的数值预测,预测结果与实验测试结果吻合较好,验证了计算方法的合理性;在此基础上,考虑成型时间与固化质量的协同控制,采用实验设计(DOE)与粒子群算法集成的优化策略开展复合材料C形构件的固化温度曲线优化设计,并对优化结果进行实验验证.结果显示通过温度曲线优化设计,在满足固化均匀性、固化程度与固化变形约束的同时,可以有效减少成型时间,两个优化算例的成型时间分别减少了64％和45％.     

航天复合材料用低温固化改性环氧树脂体系的研究

0引言 连续碳纤维增强热塑性树脂改性环氧基体复合材料在航空材料领域具有广泛的应用。这类材料韧性好，耐热性优良（可耐150℃的高温），易加工，可作为纤维的预浸料，也可用于热压罐成型。一般地，这类复合材料在热压罐成型时都是使用高温固化（HTC）（如，〉180℃）来达到优异的性能。     

模具对复合材料构件固化变形的影响分析

通过光纤光栅的方法实验研究了在热压罐成型工艺过程中, 复合材料构件由金属固化模具与复合材料构件热不匹配导致的沿厚度方向和面内的固化残余应力发展, 得到了固化后残余应力沿构件厚度方向和面内的分布情况, 并分析了该残余应力分布的产生机制以及对构件固化后变形的影响。结果表明: 复合材料与模具之间的热不匹配导致的固化残余应变沿构件厚度方向呈梯度分布, 靠近模具端大于远离模具端, 并且该应变会引起构件固化后的翘曲变形, 变形以沿纤维方向为主。     

模具对复合材料构件固化变形的影响分析

通过光纤光栅的方法实验研究了在热压罐成型工艺过程中,复合材料构件由金属固化模具与复合材料构件热不匹配导致的沿厚度方向和面内的固化残余应力发展,得到了固化后残余应力沿构件厚度方向和面内的分布情况,并分析了该残余应力分布的产生机制以及对构件固化后变形的影响.结果表明:复合材料与模具之间的热不匹配导致的固化残余应变沿构件厚度方向呈梯度分布,靠近模具端大于远离模具端,并且该应变会引起构件固化后的翘曲变形,变形以沿纤维方向为主.     

复合材料变厚层板热压成型缺陷类型与成因实验研究

采用热压机工艺与热压罐工艺两种成型方法制备了玻璃纤维/环氧 648 变厚度层板 , 研究了两种工艺下缺陷的形成机制及铺层方式和变厚梯度对缺陷程度和分布的影响。结果表明 : 纤维分布不均、 富树脂、 分层是主要缺陷类型 , 其中纤维分布不均由树脂二维流动引起 , 并与纤维不连续区、 纤维层渗透特性以及外压的均匀性有关; 富树脂主要是纤维的不连续性造成的 ; 而分层缺陷与纤维分布和热膨胀各向异性紧密相关。研究结果对变厚度复合材料层板的缺陷消除和成型质量控制有重要的指导意义。      

模具对柱面复合材料构件固化变形影响的有限元分析

针对复合材料构件固化变形问题, 分析了复合材料热压罐成型固化过程的多场耦合关系, 考虑模具的作用, 建立了柱面复合材料构件固化过程的有限元分析模型。基于此模型, 研究了模具材料、 模具厚度和模具形式对柱面复合材料构件固化变形的影响。结果表明: 模具对柱面件固化变形的影响较大, 模具材料与构件材料热膨胀系数(CTE)不匹配程度影响构件回弹角的大小; 模具的厚度不同, 导致构件的不同回弹角; 采用阴模时, 构件回弹角小于阳模的, 且回弹方向相反。     

VARI工艺成型纤维增强树脂复合材料层合板厚度和纤维体积分数的影响因素

分析了影响真空辅助成型技术（VARI）工艺成型复合材料的纤维体积分数和厚度均匀性的关键因素,即VARI成型工艺的树脂流动控制形式、纤维预制体状态、织物状态、树脂黏度,通过试验分析了各因素对VARI成型复合材料厚度和纤维体积分数的影响。试验结果表明,采用HFVI（high fiber-volume vacuum infusion）工艺、BA9914树脂及真空处理后的U3160单向机织物成型的纤维增强树脂复合材料层合板,其纤维体积分数和厚度均匀性能够接近预浸料/热压罐成型的复合材料制件的水平。     

基于组合芯模维形传压的复合材料帽型加筋构件固化过程压力分布及成型质量

为改善硅橡胶芯模辅助成型中调型孔工艺窗口过窄，导致复合材料帽型件成型质量对其敏感性过高问题，提出硅橡胶芯模&真空袋气囊组合新方法，并对不同调型孔硅橡胶芯模&真空袋气囊下成型的复合材料帽型件固化过程中压力分布和固化后成型精度、微观结构与力学性能进行了研究。结果表明：未开设调型孔&真空袋气囊，构件内部压力大小波动明显且不均分布，随着孔占比X_S的增大，在X_S=0.40～0.53内，构件内部压力均匀且稳定在所需压力0.6 MPa，同时，构件厚度和型腔高度平均差值仅为0.046 mm和0.40 mm，其三角区域微观结构质量较高，平均拉脱性能和增幅分别为3.42 MPa和23.02%。本文提出的方法具有更宽的调型孔工艺窗口，在复合材料帽型件固化成型领域具备一定应用潜力。     

Statistical Study of Delamination Area Distribution in Composite Components Fabricated by Autoclave Process

As the most frequent defect in composite structures during fabricated by autoclave process, delamination has evidently influence on compressive behavior of delaminated composite panels. For structure design purposes, delamination area is of great importance parameter to be considered. Based on considerable delamination information from non-destructive identification for composite components, a statistical study was in detail presented to investigate how delamination area in different composite components distributed. The distribution model of delamination area was hypothesized and tested by normal W test and normal D test. With consideration combined by the dispersibility and the qualified rate of delamination area, an effective method for estimating the manufacturing quality of composite components was also established. The results indicated that a lognormal distribution was found to represent the delamination area quite well and about 100 mm² had the maximum probability. Moreover, the complexity and the thickness of composite structures had significantly influence on the qualified rate of delamination area. The more complex structure and the thinner or the thicker composites decreased the qualified rate of delamination area.     

Manufacturing Influence on the Delamination Fracture Behavior of the T800H/3900-2 Carbon Fiber Reinforced Polymer Composites

'Torayca' T800H/3900-2 is the first material qualified on Boeing Material Specification (BMS 8-276) which utilizes the thermoplastic-particulate interlayer toughening technology. Two manufacturing processes, the autoclave process and the fast heating rated Quickstep™ process, were employed to cure this material. The Quickstep process is a unique composite production technology which utilizes the fast heat transfer rate of fluid to heat and cure polymer composite components. The manufacturing influence on the mode I delamination fracture toughness of laminates was investigated by performing double cantilever beam tests. The composite specimens fabricated by two processes exhibited dissimilar delamination resistance curves (R-curves) under mode I loading. The initial value of fracture toughness G_IC-INIT was 564 J/m² for the autoclave specimens and 527 J/m² for the Quickstep specimens. However, the average propagation fracture toughness G_IC-PROP was 783 J/m² for the Quickstep specimens, which was 2.6 times of that for the autoclave specimens. The mechanism of fracture occurred during delamination was studied under scanning electron microscope (SEM). Three types of fracture were observed: the interlayer fracture, the interface fracture, and the intralaminar fracture. These three types of fracture played different roles in affecting the delamination resistance curves during the crack growth. More fiber bridging was found in the process of delamination for the Quickstep specimens. Better fiber/matrix adhesion was found in the Quickstep specimens by conducting indentation-debond tests.     

Out-of-autoclave cure cycle study of a resin film infusion process using in situ process monitoring

Liquid resin infusion (LRI) of textile tailored reinforcements (TRs) is increasingly applied in new processing technologies for manufacturing carbon fibre composites. This work presents a cure cycle study of an out-of-autoclave toughened resin film infusion (RFI) process as part of the examination of an alternative manufacturing process for composites. To successfully produce laminates using resin film infusion in combination with a fast-curing process, the flow behaviour of the selected resin material under changed processing conditions was investigated. The effect of processing parameters, specifically heating rates and dwell times, on resin viscosity and laminate infiltration was evaluated through experimental work and supported by in situ process monitoring. A DC-resistance sensor system was applied to track the change in resin viscosity during cure. Results showed that cure cycles with a relatively short dwell time and higher heating rate compared to an autoclave cure led to enhanced flow properties of the toughened resin system. High quality laminates, comparable to autoclave panels, were manufactured with vacuum pressure only by modifying the original vacuum bagging arrangement.     

吸湿后复合材料层合板快速加热分层扩展数值模拟

为研究复合材料层合板吸湿后的分层现象,首先建立了吸湿后复合材料层合板快速加热导致分层损伤的有限元模型,并对ABAQUS有限元软件进行二次开发,通过UAMP子程序模拟吸湿后复合材料快速加热时水分汽化引起的局部高压载荷作用下层合板分层扩展与载荷施加过程;然后,采用该模型预测了饱和吸湿T650-35/HFPE-II-52碳纤维聚酰亚胺复合材料层合板快速加热至310 ℃时产生的分层现象,并将数值模拟与文献实验结果对比;最后,运用该模型分析了树脂吸湿量和富脂区树脂聚集体积对层合板分层损伤面积的影响。结果表明:建立的有限元模型有效;快速加热后,层合板的分层损伤面积随树脂吸湿量的增加而增加;当富脂区树脂聚集体积较小时,其对层合板快速加热后分层损伤面积影响较小,但当富脂区树脂聚集体积增加到一定值后,层合板分层损伤面积随富脂区树脂聚集体积的增加而显著增加。所得结论表明,使用ABAQUS的UAMP子程序建立的有限元模型可以有效分析吸湿后复合材料层合板快速加热导致的分层现象。      

An experimental study of low velocity impact response in 2/2 twill weave composite laminates manufactured by a novel fabrication process

A novel fabrication process for advanced composite components—the Quicktep^TM process was described. 2/2 twill weave MTM56/CF0300 carbon epoxy composite laminates were manufactured by the Quickstep and the autoclave processes. The response of these laminates to drop-weight low velocity impact at energy levels ranging from 5 to 30 J was investigated. It was found that the laminates fabricated by the Quickstep had better impact damage tolerance than those fabricated by the autoclave. Optical microscopy revealed extensive matrix fracture in the center of the backside of the autoclave laminates indicating the more brittle property of the epoxy matrix cured by the autoclave process. Interfacial shear strength (IFSS) for two composite systems were measured by micro–debond experiments. The MTM56/CF0300 material cured by the Quickstep showed stronger fibre matrix adhesion. Since the thickness and density of the impact targets produced by two processes were different, finite element analysis (FEA) was performed to study the effect of these factors on the impact response. The simulation results showed that the difference in thickness and density affects the stress distribution under impact loading. Higher thickness and lower density caused by processing lead to less endurance to drop weight impact loading. Therefore the better performance of Quickstep laminates under impact loading was not due to the thickness and density change, but resulted from stronger mechanical properties.     

A review of mechanical drilling for composite laminates

Composite laminates (CFRP, GFRP, and fiber metal composite laminates) are attractive for many applications (such as aerospace and aircraft structural components) due to their superior properties. Usually, mechanical drilling operation is an important final machining process for components made of composite laminates. However, composite laminates are regarded as hard-to-machine materials, which results in low drilling efficiency and undesirable drilling-induced delamination. Therefore, it is desirable to improve the cost-effectiveness of currently-available drilling processes and to develop more advanced drilling processes for composite laminates. Such improvement and development will benefit from a comprehensive literature review on drilling of composite laminates. This review paper summarizes an up-to-date progress in mechanical drilling of composite laminates reported in the literature. It covers drilling operations (including conventional drilling, grinding drilling, vibration-assisted twist drilling, and high speed drilling), drill bit geometry and materials, drilling-induced delamination and its suppressing approaches, thrust force, and tool wear. It is intended to help readers to obtain a comprehensive view on mechanical drilling of composite laminates.     

Mixed-mode analysis of superimposed thermo-elastic effects in fiber-reinforced composites with embedded interface delaminations

This paper deals with the 3D finite element analysis of superimposed thermo-elastic effect on embedded interfacial delamination crack growth characteristics in fiber-reinforced laminated composites. Interlaminar fracture at the delamination front is found to be a mixed-mode phenomenon due to the anisotropy and heterogeneity of thermo-physical properties of composite materials. This leads to the requirement of finite element evaluation of energy release rates, based on the principles of linear elastic fracture mechanics. The strain energy release rate components along the delamination front due to a uniform temperature drop, during the manufacturing stages of composite laminates, to room temperature and subsequent mechanical loading is obtained by superimposing their respective effects based on the assumptions of linear elasticity. Numerical calculations are carried out for multi-layered cross-ply and angle-ply composite laminates and energy release rate plots demonstrate large asymmetries along the delamination front due to the interaction of residual stresses and superimposed transverse loading.     

可剥布对T300/Cycom 970环氧树脂复合材料胶接性能的影响

在商用飞机复合材料结构制造过程中,可剥布在复合材料共胶接和二次胶接的表面处理过程中应用越来越广泛,逐步替代传统打磨方式。然而在实际应用中,可剥布与复合材料树脂体系之间存在一定的匹配性,经不同可剥布处理后的复合材料表面胶接性能存在较大差异。为研究其对胶接性能的影响,选用四种航空用可剥布对复合材料进行表面处理,采用热压罐工艺制备T300/Cycom 970环氧复合材料层压板,选取同一种航空用胶膜进行胶接。按照ASTM剥离测试和单搭接剪切测试标准,对T300/Cycom 970环氧复合材料胶接结构的性能进行测试,采用接触角测试、SEM和X射线能谱测试(XPS)分别对复合材料层压板制件和可剥布织物的表面润湿性、表面形貌和表面元素进行测试与分析。结果表明:选用聚酯湿可剥布处理后的T300/Cycom 970环氧复合材料胶接性能最佳;可剥布织物及涂层的残留会影响复合材料胶接性能;可剥布处理能改善复合材料表面润湿性,提高表面能,但并不能保障胶接质量;可剥布编织形式直接影响复合材料表面形貌,决定其表面粗糙度,对复合材料胶接性能也有较大的影响。     

A risk-based approach to manufacturing process control: use in autoclave moulded composite sandwich panels

The quality of a design solution is largely the consequence of making informed decisions based on the quality of available information. This information is not always accurate or reliable and therefore its use is not without risk, forcing designers to be conservative. The design of mechanical components is dependent amongst other things on the materials and manufacturing processes utilised. Composites are unique in that the component configuration, material and manufacturing process can be simultaneously manipulated, allowing highly optimised structures to be designed. Risk analysis is a pragmatic way of managing the variability of such information and therefore the risk associated with design for manufacture decision-making. This paper investigates the use of statistical process control techniques for improving the consistency of autoclave moulded composite components.