车用GFRP/高强度钢一体化成型工艺中异质界面粘附机理与极端工况下的失效演变

Replacing part of steel by polymer-based composites and constructing metal-polymer hybrid components could reduce the weight of vehicles. However, the property difference between dissimilar materials makes the internal stress at the interface unavoidable, which will produce connection failure under some extreme conditions. This project will study the possible mechanisms of adhesion formation at the heterogeneous interface which integrates glass fiber-reinforced polymer (GFRP) with high strength steel (HSS) within one hybrid component, and the failure process of interfaces or GFRP in hybrid components under extreme conditions, such as car-crash, fatigue loading, used in high or low temperature environment, or soaked in rainwater. Combining molecular dynamics with micro-scale finite element method, the flowing and curing process of the melt polymer on the HSS surface, and the adhesion formation and micro-mechanical interlock at the interface will be studied, and the influences of micro or macro factors on the interface properties will be investigated. By macro-scale finite element simulation, experimental measurement and analytical analysis, the constitutive relationship and failure criterions of the GFRP/HSS interface will be established, and the failure propagation under abovementioned extreme conditions will be analyzed. Through the calculation of equivalent interface properties corresponding to different fabrication process, the mapping relationships between macro-scale interface properties with micro-scale factors will be established. The failure prediction theory and method for heterogeneous interface in GFRP/HSS hybrid components will be proposed, which could provide a theoretical guidance for the selection of fabrication technologies, the control of multi-factors, and the integrated material-structure design of GFRP/HSS hybrid thin-walled beams in vehicles.

用聚合物基复合材料替代部分金属并融合为金属-聚合物混合结构，虽然有利于汽车轻量化，但是两种材料本身的性能差异不可避免地导致异质界面的内应力，在极端条件下会发生界面分离。课题研究车用玻璃纤维增强聚合物（GFRP）与高强度钢（HSS）一体化成型零件中异质界面形成与粘附机理，及其在碰撞、疲劳、高低温和雨水浸泡等极端工况下的界面性能退化过程。应用分子动力学和微尺度有限元法，研究熔融态聚合物在HSS表面流动、固化、形成界面吸附和微观机械锁合过程及其影响界面性能的因素；应用宏观尺度有限元、实验测试和理论分析，研究GFRP/HSS混合结构的界面材料本构关系和失效准则，分析极端工况下的失效演变；通过界面材料在不同工艺处理时的等效特性计算，建立微观状态与宏观界面性能的映射关系。提供的异质界面失效预测理论和方法，为车用GFRP/HSS复合薄壁梁构件的工艺选择、参数控制和材料-结构一体化设计提供理论指导。

GFRP/HSS混合结构可以兼顾轻量化和承载，在汽车行业有很大的潜在市场。课题针对异质界面的粘附机理和静动态极端工况下的失效演变开展研究。分别在纳观、微观和宏观尺度下，应用分子动力学、微尺度力学和宏观有限元法，揭示了界面粘附机理。仿真分析了熔融态聚合物在HSS表面流动和固化过程，揭示了界面形成过程，实现了工艺过程的控制。获得了各种因素对界面宏观力学性能的影响规律，建立不同尺度间的对应关系。采用仿真和试验相结合的方法，系统研究了试件在静态拉伸、单搭接剪切、三点弯曲、湿热环境、低速落锤冲击和高应变率冲击等典型工况下的力学性能。建立并验证了界面本构关系，实现了冲击失效演变预测。设计并制作了模具，加工了宏观尺度的抗弯横梁结构，完成了静态力学性能测试。提出了材料、结构和工艺的一体化设计方法和定性指标定量化的评估方法。以本项目为致谢第一标注，发表SCI检索论文8篇，EI检索国际会议论文5篇，授权发明专利1项。研究成果为该项技术的推广，提供了理论指导。