RTM工艺中单向纤维排列中的缺陷迁移的数值模拟

Decreasing the amount of residual voids during the resin infiltration into fibrous porous media is an important aspect in manufacturing high performance composite materials.In order to better understand void transports and flow behaviors in filling process,which affects immediately the final void content,a finite-element scheme for transient simulations of the void migration in a transverse flow through the uniaxial micro-structured fibrous media is developed in this work.A volume-of-fluid (VOF) method has been incorporated in the Eulerian frame to capture the free surface of the resin flow.The implementation of periodic boundary condition to the vertical direction avoids unwanted wall effect.The void migration in a dual-scale fiber tow model was investigated.The voids are observed to be transported through the inter-tow region as well as entrapped into fiber tow.It is that the motion of void lagged behind macro flow front which implies that the adequate resin bleeding after mold filling is crucial to remove the entrapped air.     

复合材料柔性RTM工艺的研究进展

树脂传递模塑工艺(Resin transfer molding,RTM)已经成为一种主要的复合材料低成本制造工艺,近些年获得了很大的发展.针对传统RTM工艺制件纤维体积含量低、不能整体成型复杂构件等不足,衍生出很多新的RTM工艺,柔性RTM工艺便是其中一种.柔性RTM工艺能够整体成型内部结构复杂、纤维含量要求较高的高性能复合材料,在制造航天航空等复合材料构件方面有着独特的优势.主要总结回顾了近几年来柔性RTM工艺的研究进展,并指出了柔性RTM工艺现存的不足.     

树脂传递模塑-复合材料成型新工艺

树脂传递模塑是一种新型的树脂基复合材料成型方法 ,具有许多独特的优点 ,近年来发展迅速。本文全面综述了该方法的工艺过程及研究应用概况 ,介绍了今后进一步发展的方向。     

树脂传递模塑成型注模过程的光纤光栅监测

有效监测树脂传递模塑成型(RTM)的树脂注模过程对于生产大型共固化复合材料结构十分必要.本文重点讨论利用光栅传感器监测注模过程的树脂流动问题.本文在复合材料层的不同位置布置了1个温度传感器用来监测温度,2个应变传感器用来监测树脂流动前沿到达时间,试验结果表明50 min和115 min时树脂流动前沿分别到达No.1和No.2应变传感器,166 min时完成注模,此时监测温度为最低的24.59℃.光栅传感器完全可实现树脂传递模塑注模过程的监测.     

树脂传递模塑成型的光纤光栅监测

复合材料固化过程对于生产高质量复合材料部件十分必要。文中利用光栅传感器监测树脂传递模塑(RTM)复合材料层板制造过程中内应变及温度,根据复合材料内应变/温度关系曲线的突变点,获得复合材料的材料转变点(凝胶点、玻璃化转变温度)信息。在复合材料降温阶段,利用光栅监测的应变/温度值计算RTM成型复合材料的内层和外层热膨胀系数。监测结果与传统检测方法相比十分一致。     

RTM成型聚酰亚胺树脂的合成与性能研究

使用4-苯乙炔苯酐(4-PEPA),3,3',4,4'-二苯醚四酸二酐(ODPA),3,4-二氨基二苯醚(3,4-ODA),1,3-双(4-氨基苯氧基)苯(1,3,4-APB)和1,4-双(4'-氨基-2'-三氟甲基苯氧基)苯(6FAPB)分别合成了六种设计分子量为1250的聚酰亚胺低聚物RTM1-6,并对低聚物的熔体黏度及熔体黏度稳定性和热性能等进行了系统研究.实验结果表明,用含有醚键及氟原子的混合二胺合成的系列树脂,其熔体黏度较低,熔体稳定性较好,可用于RTM成型工艺.但树脂的玻璃化转变温度相对较低.     

一种适用于树脂传递模塑工艺的双马来酰亚胺改性酚醛树脂

合成了一种双马来酰亚胺改性酚醛树脂，研究了加工性能，固化树脂的力学性能和耐热性。应用一种高温固化剂于该树脂体系中，并探讨了它对树脂性能的影响。制备了这类树脂与玻璃布的复合材料，评价了不同温度下的力学性能。结果表明，改性树脂具有适用于RTM工艺的良好加工性能，高温固化剂的使用能较大幅度地提高树脂的耐热性。在300℃下，复合材料的弯曲强度和保持率分别为73％和83％。     

RTM用双马来酰亚胺树脂流变特性研究

树脂粘度对于树脂传递模塑成型工艺而言是必要的参数之一。本工作对一种RTM用双马来酰亚胺树脂的流变特性进行较为系统的研究，并根据双阿罗尼乌斯方程，建立了与实验数据较为相符的化学流变模型，同时对该树脂进行牯彦预测．为确审该树脂的RTM工艺窗口提供了可靠的理论依据。     

RTM用高性能改性马来酰亚胺-三嗪树脂的研究

采用树脂转移模塑(RTM)工艺制备先进复合材料的关键是高性能树脂基体的选择.以N,N’-二氨基二苯甲烷双马来酰亚胺(BDM)、O,O′-二烯丙基双酚A(DBA)和双酚A型氰酸酯(CE)为树脂基体(简称为BD-CE树脂),以超支化聚硅氧烷(HBPSi)为活性稀释剂,开发了适用于RTM工艺的高性能改性树脂体系(mRTM)....     

RTM成型过程中树脂/纤维界面性能表征及分析

通过测试树脂的表面张力、碳纤维的表面能以及树脂与纤维动态接触角来分析RTM成型过程中树脂/纤维界面性能,并对比分析了树脂对涂覆溶液定型剂前后的纤维浸润性能的影响。结果显示,随着温度升高,树脂表面张力降低,纤维的表面能升高,使得树脂/纤维的动态接触角变小,利于树脂浸润单丝纤维;树脂对涂覆溶液定型剂后的碳纤维织物浸润较为困难。     

用于树脂传递模塑的高性能树脂基体EI

概述了树脂传递模塑（ＲＴＭ）技术的特点，用于ＲＴＭ技术的树脂基体的要求和树脂基体的发展概况。着重介绍高性能树脂基体。     

苯并噁嗪树脂流变特性及工艺窗口预报研究

苯并噁嗪树脂是一种适宜RTM工艺的新型耐烧蚀开环聚合酚醛树脂,本工作对该树脂的流变特性进行研究.在粘度实验和DSC热分析实验的基础上,依据双阿累尼乌斯方程建立了与实验数据较为吻合的化学流变模型.模型可揭示树脂在不同工艺条件下的粘度变化规律,定量预报树脂的低粘度平台工艺窗口,为该树脂RTM工艺窗口的确定以及RTM工艺参数优化提供了的科学依据.     

Heat Transfer Analysis of Non-isothermal Resin Transfer Molding by the Finite Element Method

In resin transfer molding (RTM) a stack of fiber mats or woven rovings is laid in the mold cavity. Then the mold is sealed and resin is injected. The mold and the resin can be heated in order to accelerate, by diminishing the viscosity of the resin, the filling of the mold. Proper care must be given so that polymerization is not initiated before the mold is completely filled. Therefore it is necessary to analyze the heat transfer phenomenon so as to control the temperature of the resin during the filling process. The heat equation contains convective terms that require special attention if a stable numerical scheme is to be obtained. The purpose of this paper is to describe the Taylor-Galerkin numerical method used to solve the heal equation as the mold fills up and to present some examples of simulations for three-dimensional parts.     

RTM用环氧3266树脂体系化学流变特性的研究

本研究在基本的黏度实验和DSC热分析实验的基础上,采用双阿累尼乌斯方程研究了RTM用环氧3266树脂体系的化学流变特性,建立了相应的化学流变模型,模型与实验结果具有良好的一致性.模型揭示了该树脂体系在不同工艺条件下的黏度变化规律,定量预报了该体系的低黏度工艺窗口平台,为合理制定RTM工艺参数保证产品质量和实现工艺参数的全局性优化提供了必要的科学依据.     

Processing of Sisal Fiber Reinforced Composites by Resin Transfer Molding

In this paper, a linear flow model based on Darcy's law was used in the experiment to measure permeability of sisal textile. The Kozeny-Carman equation was employed to predict the permeability of sisal textile and the Kozeny constant was calculated through experimental results. Both experimental and predicted permeability values of sisal textiles were compared. Effects of fiber surface treatments and fiber volume fraction on the permeability of sisal textile were also studied in this research. Comparisons of mechanical properties of sisal-textile-reinforced composites manufactured by different processing technologies were made.     

注射成型流道温度分布的测量分析方法

树脂温度的分布对注射成型过程的充填平衡具有重要影响。由于型腔中传感器的安装空间有限,至今为止还没有合适的方法来测量注射成型过程中流道和小尺寸型腔中树脂温度场的分布。为了解决这一问题,文中设计了一套新式的移动式温度测量系统,该系统采用常规尺寸红外线传感器和红外线纤维传感器来测量注射模具流道内树脂温度场分布。测量结果显示,...     

RFI工艺中有关树脂流动监测的研究

渗透率测定是树脂膜熔渗(RFI)工艺在复合材料设计和优化中最关键的技术.基于光导纤维视觉技术,通过纤维视觉传感器测量渗透率,能够在光强度下降的情况下探测出树脂的前进情况,这将易于我们在实际生产中在第一时间内准确地监测树脂的流动.     

Resin flow analysis with fiber preform deformation in through thickness direction during Compression Resin Transfer Molding

Resin flow during Compression Resin Transfer Molding (CRTM) can be best described and analyzed in three phases. In the first phase, a gap is created by holding the upper mold platen parallel to the preform surface at a fixed distance from it. The desired amount of resin injected into the gap quickly flows primarily over the preform. The second phase initiates when the injection is discontinued and the upper mold platen moves down squeezing the resin into the deforming preform until the mold surface comes in contact with the preform. Further mold closure during the final phase will compact the preform to the desired thickness and redistribute the resin to fill all empty spaces. This paper describes the second phase of the infusion. We assume that at the end of phase one; there is a uniform resin layer that covers the entire preform surface. This constrains the resin to flow in through the thickness direction during the second phase. We model this through the thickness flow as the load on the upper mold forces the resin into the preform, simultaneously compacting the preform. The constitutive equations describing the compaction of the fabric as well as its permeability are included in the analysis. A numerical solution predicting the flow front progression and the deformation is developed and experimentally verified. Non-dimensional analysis is carried out and the role of important non-dimensional parameters is investigated to identify their correlations for process optimization.