汽车撞击护栏时乘员的安全性研究

STUDY ON THE PASSENGER SAFETY DURING THE IMPACT PROCESS OF AUTOMOBILE AGAINST FENCE

应用LS-DYNA软件,通过建立完整的三维“汽车-道路-护栏-乘员-座椅-安全带”模型,研究了汽车撞击护栏时车内乘员的安全性,得出如下重要结论:①采用完整的三维“汽车-道路-护栏-乘员-座椅-安全带”模型,能够模拟碰撞中乘员的运动与受力状态,对提高护栏的安全性设计水平有更直观的效果,对护栏评价标准的进一步发展也有重要意义,在VPG技术日益完善的今天,开展这种完整的系统研究不仅十分必要,而且切实可行;②安全带对乘员的约束大大提高了碰撞过程中乘员的安全性。分析结果表明:未系安全带的假人,不仅头部的HIC值已接近人体的耐冲击阈值,假人胸部的合成减速度峰值也偏高,且假人飞离座椅再撞击乘座室内部物体的可能性也很大,因此,一旦发生交通事故,即使是大型车辆,车内乘员的安全也将遭受严峻的考验。事实上,安全带在小型乘用车上的成功应用,大大提高了碰撞过程中乘员的安全水平,因此,在安全带日益得到推广应用的今天,在高速公路及高等级公路飞速发展的今天,是考虑大型车辆配置安全带的时候了。③在汽车撞击标准混凝土护栏的过程中,在汽车车体与混凝土护栏发生接触前即发生侧翻,亦即混凝土护栏的高度对预防汽车的侧翻基本不起作用,那种在山区公路及危险路段普遍采用标准混凝土护栏的做法并不科学,即使增加了混凝土护栏的高度也是如此;④在汽车-护栏碰撞系统CAE分析中,如果需要捕捉到车辆侧翻事故发生的可能性,则仿真的碰撞时间不宜太短,至少要超过950ms。

The safety of passenger during the impact process of automobile against fence is studied by the integrated model of “automobile-road-fence-passenger-passenger seat-safety belt” based on LS-DYNA, and the important results are gained as below:①The movement and forced state of passenger can be simulated in the course of impact by the integrated three-dimension model of “automobile-road-fence- passenger - passenger seat-safety belt”, which has great signifigance and direct effect on improving the design level of safety and developing the assessment standard of fence. The study on the integrated system is not only necessary but also feasible along with the increasingly perfect technology of VPG;②The safety of passenger is increased by the restriction of the safety belt during impact process. It is indicated from the analysis results that the HIC of head is closer to the anti-impact utmost of human body, the peak value of the compound deceleration of the chest is higher and the probability of impact of the body to object in the cab after deviating from seat is bigger than that of the dummy without safety belt. Once the traffic accident happensd, the safety of passenger will suffer from a severe test even in a large-scale automobile. In fact, the safety of passenger is increased when successfully applying safety belt in minitype automobile. It is the time to deploy the safety belt in large-scale automobile with the rapid advance of the freeway and higher grade road.③During the impact process of automobile against fence, the concrete fence is usually not effective to prevent the overturn of the car, because the overturn more often than not has happened before the car body comes into contact with the concrete fence, and the prevalent design standard of concrete fence adopted in the mountainous area road and danger section of highway is unscientific, even if the height of the concrete fence is raised.④If it is necessary to catch the possiole overturn accident in CAE analysis on the automobile-fence impact system, the simulation impact time should be more than 950ms.