道路交通事故导致的人员伤亡是一个严峻的公共安全和卫生问题，乘员约束系统能够对碰撞中车内人员起到保护作用，但是其保护效果受到碰撞强度、乘员乘坐姿态、体型以及约束系统的形式和参数配置等因素的影响。围绕影响乘员损伤响应的因素，现有研究未能实现乘坐姿态和碰撞强度的影响与其他因素影响的解耦、缺乏针对不同体型的乘员进行安全带和气囊参数调节的系统性策略，且现有针对约束系统形式或参数的优化并未从根本上解决安全带和气囊本身的副作用。解决上述问题可以指导现有约束系统的优化、新型约束系统的研发和乘员碰撞保护策略的设计。针对上述问题，本文展开了考虑乘员体型、乘坐姿态和碰撞强度影响的乘员约束系统和损伤响应研究。首先，通过提出均衡约束形式、进行不同工况下的约束系统参数配置矩阵仿真，解析约束系统参数配置、碰撞强度、乘坐姿态对乘员损伤响应的影响规律和机理，并评价碰撞强度影响下的均衡约束保护效果。发现后倾乘坐姿态和较高的正面碰撞强度都有导致内脏应变和脊柱压力增大的固有风险。均衡约束下的胸腔变形呈对称的楔形模式，具有更低的损伤风险，使得即使在单一的约束系统参数配置下，均衡约束仍可以在较宽范围的碰撞强度下给乘员提供有效保护。然后，通过搭建安全带和气囊的约束系统参数配置自动化研究平台，以中美人体的体型差异为例，针对不同范围体型的乘员，进行约束系统参数配置优化策略研究。发现通过调节气囊充气质量流速，可以实现对不同范围体型乘员保护的设计切换。但如果不调节约束系统参数配置，胸部损伤使得体型小于范围下限的乘员不能得到有效保护。因此，为了提升人体有限元模型这一研究工具对弱势群体胸部特征的表征能力，以真实人体老龄化过程中常见的肋软骨钙化这一生理现象为例，进行在人体有限元模型中进行肋软骨钙化表征的方法研究。基于真实人体的数据，通过建立肋软骨内解剖学位置标识系统，提出了在人体有限元模型中进行个体的或人群中平均的肋软骨钙化表征的方法。最后，对比现有约束形式和均衡约束形式在乘员体型影响下的保护效果，发现即使在单一的约束系统参数配置下，均衡约束仍可以给较宽范围体型的乘员提供有效保护。并利用肋软骨钙化表征方法改进现有人体有限元模型，对改进后的模型进行仿真计算的应用示范。
Fatalities and injuries caused by road traffic accidents have emerged as a serious public health problem. Occupant restraint system can protect occupants in vehicle collision accidents, but its protection effect is affected by crash severity, occupant sitting posture, occupant body size, form and configuration of the restraint system, and some other factors. Previous studies on factors affecting occupant injury response showed that the influences of sitting posture and crash severity coupled with other factors have not been studied in-depth. A systematic strategy for adjusting the parameters of seatbelt and airbag has not been available for protecting occupants with diverse body sizes. In addition, the existing optimized restraint systems cannot fundamentally avoid the potential hazards of seatbelts and airbags. Solving these problems is important for existing restraint systems optimization, new restraint systems design and strategy-making for occupant protection. This thesis carried out a research on occupant restraint system and injury response concerning influences of occupant body size, sitting posture and crash severity.First, by proposing a uniform restraint form and conducting simulation of restraint system parameter configuration matrix, the influence and mechanisms of restraint system parameter configuration, frontal crash severity, and sitting posture on the occupant injury response were analyzed. Protection effect of the uniform restraint under different crash severities was evaluated. It has been found that reclined sitting posture and high frontal crash severity have respective inherent risks that lead to increase of visceral strain and spinal pressure. The thoracic deformation under the uniform restraint shows a symmetric wedge-like pattern, which has a lower injury risk. Even with a single set of parameters configuration, the uniform restraint can protect occupants effectively under a wide range of crash severity.Second, an optimization strategy of the seatbelt and airbag parameter configuration for different occupant body sizes was studied. An automatic simulation platform for studying the parameter configuration of the seatbelt and airbag was constructed. The differences between the Chinese and American body sizes were considered in this work. It has been found that, by adjusting the inflation mass flow rate of the airbag, the restraint system for protecting Chinese body sizes can be switched to that for American body sizes, and vice versa. Under a restraint system with parameter configurations optimized for protecting occupants of a specific body size range, an occupant with a body size smaller than its lower limit cannot be protected effectively due to the thoracic injury. Consequently, to improve the ability of human finite element models (FE HBMs) to represent the thoracic characteristics of vulnerable occupants, the costal cartilage calcification, a common physiological phenomenon in the aging process, was studied as an example, and a method was proposed to represent costal cartilage calcification in HBMs. Based on real human data, by establishing an anatomical indexing system for costal cartilage, a method to represent individual or population-based average costal cartilage calcification in a human finite element model was proposed. Finally, protection effects of the existing restraint forms and the uniform restraint form concerning diverse occupant body sizes were compared. It has been found that even with a single set of parameter configuration, the uniform restraint can effectively protect occupants of a wide range of body size. Application of FE HBMs with improved characterization of the costal cartilage calcification in simulation was also demonstrated.
