碳纤维增强热塑性复合材料热压-注射整体化成形工艺与机理

The application of continuous carbon fiber reinforced thermoplastic composite is the coming development trend in present industry, and prefabricated composite plates is its main form of preparation. Thermoforming is the main method of molding composite plates into parts. However, the method can’t be employed to mold complex-structure parts, which is the bottleneck for thermoplastic composites molding. In view of that, the project proposes a novel processing method for thermoforming-injection molding integrative forming of carbon-fiber enforced thermoplastic composite, and the key basic problems in this research are as follows:1) the applicant conducts research on the deformation mechanism of carbon fiber enforced thermoplastic composite sheets under large strain, including interaction mechanism between carbon fiber and the matrix, properties of composite plate in different forming stages and constitutive model of material deformation etc. 2) the applicant studies material behaviors and bonding mechanisms on the combination interface of the injection structure and the skeleton, and focuses on the bonding interface morphology development, the dominant factors of molecular chain diffusion and penetration. In addition, a characterization model of the interfacial strength is also studied. 3) The applicant studies the evolution of carbon fiber structure during the molding process and its influence on the performance of the molding parts. Besides, a multi-layer hybrid structure model of the molding parts is built to predict the overall performance of molding parts. Based on the above work, with the thermal compression-injection molding process principles which are needed developing on the basis of process tests, a viable method will be provided for molding complex-structure parts utilizing composite plates. And it’s also significantly meaningful for extension in engineering applications of thermoplastic composites and development of high-performance lightweight manufacturing.

热塑性基连续碳纤维增强复合材料是未来发展方向，预制复合板材是其主要制备形式。热压是将复合板材成形为零件的主要方法，但存在不能成形复杂结构的瓶颈问题。为此，本项目提出一种碳纤维增强热塑性复合材料的热压-注射整体化成形新工艺，重点研究如下关键基础问题：1）大应变条件下纤维增强热塑性复合板形变机理，包括碳纤维与基体的相互影响机制、复合板的分阶段变形特征及表征材料形变过程的本构模型等；2）注射结构与骨架结合界面上的材料行为与粘结机制，重点研究结合界面微观形貌演化、分子链扩散与渗透过程、界面强度的表征模型等；3）成形中纤维结构的演变及其对最终构件性能的影响规律，构建具有多层混合结构整体构件的性能预测模型。基于上述工作，结合工艺研究建立热压-注射成形的工艺准则，将为基于复合板材的复杂结构零构件成形提供一种可行途径，对拓展热塑性基复合材料的工程应用，发展高性能、轻量化成形制造技术具有十分重要的意义。

连续碳纤维增强热塑性复合材料是航空航天、汽车等行业承载件“以塑代钢”，实现轻量化的理想材料，是国际公认的未来发展方向。针对常规工艺不能成形复杂结构特征的瓶颈问题，项目自主研发了一种复杂构件热压-注塑整体化成形新方法，并重点研究了其关键工艺基础问题。首先，项目将亲水官能团-SO3Na成功的引入到芳环，结合热压过程孔隙率建模分析与调控，制备了高性能CF/PEEK复合板材。复合板材的高温变形行为是热压工艺设计的基础，项目深入研究了不同成形条件下CF/PEEK复合板材的变形基础特性和热压成形性能，确定了板材的热压成形极限，并系统阐述了复合板材的变形失效机理。注塑过程复杂构件多层界面的形成对整体性能有关键影响，项目系统分析了复杂构件界面剪切强度影响因素和粘结机理，建立了优化界面粘结强度的工艺准则。数值模拟是成形构件整体性能预测的有效方法，项目建立了编织织物变形过程非线性各项异性特征的次弹性本构模型，结合聚合物粘弹塑性本构模型，准确描述了成形过程的取向变化与成形缺陷，基于细观力学的复合材料性能预测方法与模型，实现不同纤维结构复合材料力学性能的定量预测。基于上述工艺基础研究，项目试制出CF/PEEK典型复杂构件，验证了热压-注塑整体化成形工艺的可行性，为复杂结构整体化成形提供了一种可行途径，对拓展热塑性基复合材料的工程应用，发展高性能、轻量化成形制造技术具有十分重要的意义。