面向行人保护的夹层玻璃断裂机理及中间层调控机制研究

Vulnerable road users (VRUs) have always accounted for over 60% of the road casualties each year in China, with the head impact against the windshield laminated glass being their main death cause. The mechanical properties of interlayer material have directly affected the energy absorption capacity and crashworthiness of the laminated glass. This work focuses on CNT/PVB composite (this is formed by filling carbon nanotubes, CNT, into conventional polyvinyl butyral, PVB), and the laminated glass made of CNT/PVB interlayer, with special attention paid to the mechanical characteristics of CNT/PVB composite and the fracture mechanism of CNT/PVB laminated glass. Fundamental experiments on the viscoelasticity and dynamic tensile properties of CNT/PVB composite are carried out and the corresponding constitutive models are suggested which are capable of describing the modification mechanism of CNT. Optical caustics method is employed to capture the crack initiation and the subsequent propagation of laminated glass subjected to different loading conditions, so as to reveal the effects of constitutive properties of the interlayer composite upon the fracture characteristics of the laminated glass. Experimental tests and numerical simulations are carried out to investigate the dynamic response of CNT/PVB laminated glass subjected to headform impact. After incorporating the traffic accident recreation data and three-dimensional head model, the finite element model is employed to perform the optimization study of geometry configuration and material properties of laminated glass. The results of this work are expected to reveal - in both theoretical and experimental perspectives - how the filling of CNT affects the mechanical performance of traditional PVB interlayer, the fracture mechanism of the polymer laminated glass, and the intricate interaction between the two; this work will lay the theoretical basis for the optimal design of windshield laminated glass for VRUs' protection in engineering applications.

弱势道路使用者长期占据我国每年交通事故死亡人数的60%以上，其头部与汽车风挡玻璃接触是致其伤亡的重要原因。中间层材料的力学性质直接影响了夹层玻璃的吸能和抗冲击特性。本项目以嵌入碳纳米管（CNT）的PVB薄膜及相应的夹层玻璃为研究对象，重点关注薄膜力学特性和夹层玻璃断裂现象。通过黏弹性及动态拉伸实验建立可描述CNT调控机理的本构模型；通过焦散线法观测夹层玻璃在不同加载工况下的断裂过程，研究此类新型PVB薄膜材料属性对夹层玻璃断裂特性的影响；通过头模块冲击风挡玻璃实验及数值模拟，探讨此类新型风挡玻璃的动态力学响应；在此基础上结合交通事故再现及三维有限元头模型，对此类新型风挡玻璃进行材料与结构优化研究。通过本项目的研究，可望在实验和理论上揭示CNT对高聚物薄膜力学性能的调控机制、脆性-高聚物层合板材料的断裂机理及两者之间的联系；在工程上为汽车风挡玻璃面向行人保护的优化设计提供重要的理论指导。

夹层风挡玻璃的力学特性对于交通事故中行人头部保护有重要影响。本课题通过实验研究、理论推导和数值模拟，系统阐明了薄膜制备工艺参数及改性添加剂及对夹层玻璃中间层粘弹特性的调控规律，以及薄膜材料粘弹特性对夹层玻璃静力学特性、低速冲击下的微观断裂行为和行人保护特性的影响机制。.通过准静态拉伸试验和动态动力学分析，对添加DBS和3G8的PVB薄膜材料的力学特性展开参数化的实验研究，在总结了制备工艺条件和添加剂配比及属性对薄膜粘弹特性的影响基础上，确定了最优制备条件和含量；对改性后的PVB薄膜材料的粘弹性力学特性建立了本构模型，为后续实验的开展奠定了研究基础。.基于液压驱动试验机，对磁控溅射有多种金属及其氧化物的薄膜进行了材料力学性能测试，并对该种薄膜夹层玻璃试件与PVB夹层玻璃试件进行三点弯试验，建立了描述结构抗弯特性的理论模型，并基于此分析了不同结构和材料同参数对夹层玻璃力学性能的影响。.通过焦散线实验系统结合低速落锤平台，研究了初始冲击动能和中间层位置对夹层玻璃的微观裂纹的断裂特性和跨夹层传播行为的影响。基于应力强度因子量化表征了裂尖场强度，并建立了其与裂纹起裂和扩展行为之间的关系；基于断裂力学理论从机理层面解释了两种不同失效模态产生的原因。为夹层玻璃抗冲击防护提供了实验和理论依据。.在不同冲击速度下开展了不同中间层材料、不同中间层厚度、不同玻璃层厚度、不同夹层结构的风挡玻璃的头模块冲击实验，系统揭示了不同碰撞条件和结构参数对于风挡玻璃失效历程、行人保护特性的影响，为风挡玻璃的设计优化、相关法规制订提供了实验依据。.基于真实人车道路事故统计数据，采用多刚体动力学仿真手段得到能够反应真实事故场景的行人头部与风挡玻璃碰撞时的运动学参数分布。基于上述分布开展大规模头型冲击风挡玻璃的有限元模拟仿真，揭示了不同碰撞初始参数对头部损伤程度的影响规律，并建立了头部损伤风险预测模型，为事故重建和行人保护安全设计提供了重要的研究手段。.