先进树脂基复合材料RTM工艺的研究进展

随着复合材料的应用越来越广泛,制件产品复杂性和质量要求越来越高,逐渐衍生出多种复合材料成型工艺.而树脂传递模型(RTM)及其派生工艺是一种高质量、高精度、高效率、低成本和绿色化的闭模成型工艺.本文简要介绍了RTM成型工艺原理、RTM衍生工艺成型过程及特点、RTM工艺应用现状以及RTM用树脂的研究现状,并提出了RTM工艺...     

编织结构复合材料RTM成型流场仿真模拟

针对航空发动机用编织结构复合材料树脂传递模塑料(RTM)成型工艺,开展了增韧树脂基体的工艺特性及编织结构预制体的渗透特性研究,并结合PAM–RTM软件对RTM成型工艺方案进行了研究,研究结果表明,1304增韧环氧树脂RTM成型的工艺窗口期仅有25 min,8步法编织结构经向渗透率远大于纬向和Z向渗透率。通过PAM–RTM软件对RTM成型树脂注射流道和工艺参数进行设计,获得了航空发动机用高韧性编织结构复合材料RTM成型工艺方法。     

复合材料RTM成型工艺综述

本文主要是综述RTM成型工艺的基本原理、工艺特点,讨论了适于RTM的增强材料和树脂休系并讨论了工艺参数对RTM模制品质量的影响以及RTM在成型三维复合材料方面的应用。     

真空辅助RTM成型技术的研究

本文详细介绍了目前RTM工艺中最先进的两种真空辅助成型技术渗透介质辅助成型及引流槽辅助成型,采用这两种技术的RTM工艺能够制造超厚超大的产品,适应更加广阔市场需求,同时,真空辅助RTM成型技术RTM工艺的应用领域进一步扩大。     

高性能复合材料树脂传递膜技术(RTM)研究

树脂传递模塑法（RTM）是一种低成本、效益好的复合材料成型工艺。研究了RTM用树脂体系、预成型技术、成型模具、成型工艺以及RTM在航空航天领域的应用。     

RTM树脂材料及其辅助成型工艺研究进展

简要介绍RTM工艺的成型原理,详细介绍用于RTM的新型树脂及改性树脂材料的研究进展情况、各种RTM辅助成型的工艺进展情况,并展望RTM技术在航天航空等领域的应用。     

RTM工艺中气泡形成及消除研究

总结了关于RTM（树脂压铸）工艺中气泡缺陷的文献报道，对RTM中气泡缺陷的形成机理、影响因素及各研究者提出的消泡方法、理论和模型进行了概述，同时对RTM工艺中气泡缺陷的研究现状给予充分关注，并对RTM缺陷研究的未来方向进行了展望。     

树脂传递模塑（RTM）成型工艺及应用

本文概述了树脂传递模塑(RTM)的成型工艺过程及其应用前景。由此可了解 RTM 技术的全貌。通过对 RTM 与其它几种主要的复合材料加工工艺的比较,如SRIM(结构反应注射成型),SMC(片材成型)等,可以清楚地认识到 RTM 作为新一代复合材料加工工艺在航空、航天、航海、汽车和建筑等各个领域的发展潜力。     

气囊辅助RTM工艺用复合裙模具的设计与制备

针对某型号上用VARTM工艺制造的复合裙纤维体积含量偏低的缺点,提出用气囊辅助RTM工艺制造该复合裙。该工艺通过向气囊内充压,对预成型体施加一定的成型压力,从而提高构件纤维体积含量及力学性能。本文设计制备了气囊辅助RTM工艺用复合裙模具。工艺实验表明,借助该模具能顺利实施气囊辅助RTM工艺,制备出高性能的复合裙。     

DCPD树脂用于RTM工艺的探讨

本文通过双环戊二烯(DCPD)树脂的合成,就DCPD树脂的性能和RTM工艺的特点进行比较,得出了 DCPD树脂在 RTM工艺中的应用前景。     

铝合金RTM模具制备设计研究

复合材料成型工艺中树脂传递模塑(RTM)成型已在航空航天、汽车等制造领域得到广泛应用。但由于传统钢制模具质量太大,限制了大型复合材料制件采用RTM成型工艺的发展。设计研究了采用铝合金制备RTM成型模具的减轻质量效果,分析了克服铝合金材质热膨胀系数对模具形变影响的解决方案。结果表明,铝合金模具减轻质量效果尤为明显,相较钢模减轻50%;通过减小模具型腔尺寸,提高注胶和脱模温度、设置必要的保护装置等方法,可克服铝合金热膨胀系数大、硬度低等缺陷;并且其成型出的制品表面光洁,内部无分层和脱胶现象,尺寸精度达到设计要求。     

同步带张紧轮注塑模具RTM工艺树脂流动模拟分析

RTM工艺树脂流动的模拟对于其模具的设计有着重要的价值。就本文而言,通过同步带张紧轮注塑模具的分析,其数值的模拟对于其工艺控制有着较大的促进作用。须知道,数值充模是其工艺成型过程的关键环节,通过树脂渗透过程,逐步地指出其树脂流动的曲线。其计算结果与试验结果是基本一致的。     

预成型体质量对桨叶RTM成型工艺缺陷的影响

为考察预成型体质量对桨叶RTM成型工艺缺陷的影响,本文从预成型模具以及预成型工艺两方面对XX型复合材料螺旋桨桨叶的预成型体技术进行了研究。结果表明,在旧预成型模具的基础上改进的新型模具能精确控制预成型压力,从而可以保证预成型体的尺寸精度和质量。相比于湿法定型,达到相同的定型效果,干法定型所需的定型剂用量要少很多,后续利用RTM工艺制备得到的样件缺陷较少。     

Three-dimensional nonisothermal mold filling simulations in resin transfer molding

The manufacture of polymer composites through the process of resin transfer molding (RTM) involves the impregnation of the reactive polymer resing into a mold with preplaced fibrous reinforcements. Determination of RTM processing conditions requires the understanding of various parameters, such as material properties, mold geometry, and mold filling conditions. Modeling of the entire RTM process provides a tool for analyzing the relationship of the important parameters. This study developed a nonisothermal 3-D computer simulation model for the mold filling process of RTM based on the control volume finite element method. The model will be able to simulate mold filing in molds with complicated 3-D geometry. Results of some numerical studies in RTM show the applications of the proposed model.     

Resin transfer molding process optimization using numerical simulation and design of experiments approach

The art of resin transfer molding (RTM) process optimization requires a clear understanding of how the process performance is affected by variations in some important process parameters. In this paper, maximum pressure and mold filling time of the RTM process are considered as characteristics of the process performance to evaluate the process design. The five process parameters taken into consideration are flow rate, fiber volume fraction, number of gates, gate location, and number of vents. An integrated methodology was proposed to investigate the effects of process prameters on maximum pressure and mold filling time and to find the optimum processing conditions. The method combines numerical simulation and design of experiments (DOE) approach and is applied to process design for a cylindrical composite part. Using RTM simulation, a series of numerical experiments were conducted to predict maximum pressure and mold filling time of the RTM process. A half‐fractional factorial design was conducted to identify the significant factors in the RTM process. Furthermore, the empirical models and sensitivity coefficients for maximum pressure and mold filling time were developed. Comparatively close agreements were found among the empirical approximations, numerical simulations, and actual experiments. These results were further utilized to find the optimal processing conditions for the example part.     

Enhancement of resin transfer molding using articulated tooling

Mold articulation is introduced in this concept for resin transfer molding (RTM) to increase mold fill times and potentially allow for the use of high viscosity, hot melt resin systems, or thermoplastics. Following a brief review of conventional RTM and a discussion of the limitations on the factors that control fluid flow through porous media, the articulated concept is described. This is followed by an explanation of the sequence of motion of an articulated segmented mold necessary for consolidation, void removal and accelerated fluid flow through a fibrous preform. An analysis of the process using a fiber preform with orthotropic permeability is outlined from which mold fill time is obtained. This is compared with conventional RTM mold fill times using typical resin properties and fiber volume fractions. For the conservative assumptions used, an improvement by a factor of ten in mold fill time is achieved using the articulated process relative to conventional RTM.     

Flow channels/fiber impregnation studies for the process modeling/analysis of complex engineering structures manufactured by resin transfer molding

The success of resin transfer molding (RTM) depends upon the complete wetting of the fiber preform. Effective mold designs and process modifications facilitating the improved impregnation of the preform have direct impact on the successful manufacturing of parts. Race tracking caused by variations in permeabilities around bends, corners in liquid composite molding (LCM) processes such as RTM have been traditionally considered undesirable, while related processes such as vacuum assisted RTM (VARTM) and injection molding have employed flow channels to improve the resin distribution. In this paper, studies on the effect of flow channels are explored for RTM through process simulation studies involving flow analysis of resin, when channels are involved. The flow in channels has been modeled and characterized based on equivalent permeabilities. The flow in the channels is taken to be Darcian as in the fiber preform, and process modeling and simulation tools for RTM have been employed to study the flow and pressure behavior when channels are involved. Simulation studies based on a flat plate indicated that the pressures in the mold are reduced with channels, and have been compared with experimental results and equivalent permeability models. Experimental comparisons validate the reduction in pressures with channels and validate the use of equivalent permeability models. Numerical simulation studies show the positive effect of the channels to improve flow impregnation and reduce the mold pressures. Studies also include geometrically complex parts to demonstrate the positive advantages of flow channels in RTM.     

Flow and cure phenomena in liquid composite molding

Liquid molding processes including resin transfer molding (RTM) and structural reaction injection molding (SRIM) continue to attract attention due to their potential for high volume manufacture. This paper examines and compares the pressuare and temperature histories observed in mold cavities during impregnation, heating, and polymerization for both RTM and SRIM using polyester, vinyl ester, and polyurethane resins in combination with continuous strand mats. Experimental results are related to thermal, chemical and rheological effects. Factors which influence materials behavior and process control and the implications for mold design are discussed.     

Development of resin transfer molding process using scaling down strategy

The virtually developed resin transfer molding (RTM) manufacturing process for the large and complex composite part can be validated easily with the trial experiments on the scaled down mold. The scaling down strategy was developed using Darcy's law from the comparisons of mold fill time and mold fill pattern between full‐scale product and scaled down prototype. From the analysis, it was found that the injection pressure used in the scaled down mold should be the full‐scale injection pressure by the times of square of geometrical scale down factor, provided the identical injection strategy and raw material parameters were applied on both the scales. In this work, the RTM process was developed using process simulations for a large and complex high‐speed train cab front and it was validated by conducting experiments using a geometrically scaled down mold. The injection pressure as per the scaling down strategy was imposed on the scale downed high‐speed train cab front mold and a very close agreement was observed between the flow fronts of experimental and simulated results, which validates the scaling down strategy and the virtually developed RTM process for the full‐scale product. POLYM. COMPOS., 35:1683–1689, 2014. © 2013 Society of Plastics Engineers     

Modeling and simulation approaches in the resin transfer molding process: A review

A review of current approaches in modeling and simulation of the resin transfer molding (RTM) process is presented. The processing technology of RTM is discussed and some available experimental techniques to monitor the process cycle are presented. A master model is proposed for the entire process cycle consisting of mold filling and curing stages. This master model contains the fundamental and constitutive sub‐models for both stages. The key elements of the master model discussed in this study are: flow, heat and mass balance equations for fundamental sub‐models, permeability, cure kinetics, resin viscosity and void formation for constitutive sub‐models. At the end, numerical methods widely used to simulate the filling process are presented and published simulation results of mold filling and process cycle are reviewed.