轻量化的汽车注塑复合材料车轮抗冲击性能的提升机理及设计理论

The lightweight effect of the automotive wheel as a rotating unsprung component is significantly higher than that of sprung components. The development of composite wheels is an important way to achieve lightweight. The long fiber reinforced thermoplastic composite (LFT) has great potential in the lightweight design of the automotive wheel due to its lower cost. However, the constitutive relationship of LFT is complicated and there is a lack of design theory to improve impact toughness, which make the wheel have low ductility and easy to crack under the impact load. This has become a bottleneck problem in the research and development of automotive composite wheel. To solve above problems, the integrated simulation and design methods of the LFT wheel will be established to improve the impact resistance in this project. Firstly, the multi-scale constitutive model of the LFT with injection process will be established to reveal the load distribution mechanism and the cooperative response characteristic of the hybrid fibers and matrix in the LFT, and to explore the theory and method of toughening the LFT. Secondly, the analysis of the process and structure parameters to the injection residual stress is performed to reveal the influence rules. Then the transient stress simulation method integrating the interactions of material, process and structure under impact load will be constructed，which can be used in the toughening design of material, the selection of process parameters and the stiffness matching of the metallic insert and the LFT part. At last, the integrated simulation and optimal design methods of the material, process and structure for enhancing the impact resistance of the lightweight automotive composite wheel will be obtained. The achievements in this project may provide a novel way of the lightweight design of the automotive wheel and other carrying components, and are significant to promote the lightweight design of automobile.

作为簧下旋转件的汽车车轮其轻量化效果显著高于簧上零部件，发展复合材料车轮是实现车轮轻量化的重要途径。长纤维增强热塑性复合材料成本较低，用于车轮具有巨大轻量化潜力，但其本构关系复杂，且缺乏提升冲击韧性的设计理论，导致车轮结构韧性差、易开裂，成为研发瓶颈。本申请针对该问题，拟建立材料、工艺、结构一体化的抗冲击优化设计方法。首先建立注塑成型复合材料的多尺度本构模型，揭示长纤维增强热塑性复合材料中混杂纤维、基体的载荷分配机制和协同响应特性，探索其增韧理论和方法；并研究制造工艺及结构参数对车轮残余应力的影响规律，构建冲击载荷下综合考虑材料-工艺-结构耦合关系的车轮瞬态应力仿真方法，用于材料抗冲击韧性设计、工艺参数选择及车轮金属嵌件与复材部分刚度匹配等；最终形成抗冲击的轻量化汽车复材车轮材料、工艺及结构一体化优化设计方法。研究成果可为车轮和其他承载件轻量化提供新途径，对推进汽车轻量化具有重要意义。

本项目针对长纤维增强热塑性复合材料车轮抗冲击性能差的问题，基于细观代表性体积单元，揭示了不同纤维增强方式对复合材料力学性能的影响；基于样条试验结果，建立了反演纤维增强复合材料就位相本构特性的方法；联合模流分析软件、材料非线性分析软件以及有限元软件，准确映射增强纤维在复材车轮中的取向与分布，获得复材车轮随空间变化的材料各向异性属性，实现了长纤维增强热塑性复材车轮材料-结构-工艺一体化仿真，仿真结果与试验结果的误差小于4%，显著提升了仿真精度，为复材车轮设计方案的评估提供了有效方法，该联合仿真方法同样适用于其他注塑成型复合材料结构的性能仿真，可推动热塑性复合材料在汽车轻量化结构中的应用；仿真获得了车轮模内、模外注塑残余应力的规律及分布特点，分析了不同冲击载荷下注塑残余应力对车轮抗冲击性能的影响，结果表明对车轮进行13°抗冲击性能分析时可忽略注塑残余应力的影响；通过理论、仿真与试验分析，揭示了金属连接件与复材部分的载荷传递机理，实现了金属件与车轮复材部分的高性能连接；提出了灰色关联和主成分分析相结合的方法合理确定车轮多目标优化时各子目标的权重系数，以加权柔度最小化为目标实现车轮的多目标拓扑优化，获得多种具有良好抗冲击性能的车轮构型；提出了集成网格变形技术、混合代理模型建模方法、多目标粒子群优化算法以及多准则决策方法于一体的多目标结构优化设计方法，使所获车轮的优化结构在质量降低6.2%的情况下，最大应变降低了29.9%，显著提升其抗冲击性能。本项目提出的用于复材车轮的拓扑优化及结构优化方法同样适用于其他轻质材料车轮，可推动轻质材料车轮轻量化技术的发展。本项目探索了模压/注塑混合工艺成型复合材料车轮的抗冲击性能，初步研究表明其可满足车轮13°台架冲击试验的要求，为复合材料车轮的研发指出了新的途径。

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