目的:护栏末端端子的设计旨在使车辆在碰撞过程中逐渐减速,并保护车辆乘员免受严重伤害。据观察,一些在役终端损坏,目前尚不清楚它们的安全性能是否仍然可以接受。这项研究的目的是检查在役终端的条件,并评估在模拟冲击中相对于未损坏的末端端子的损坏性能。
方法:使用从国家汽车采样系统-耐撞性数据系统(NASS-CDS)收集的碰撞后图片,研究了护栏末端端子的常见损坏模式。通过使用第二个战略公路研究计划-道路信息数据库(SHRP2-RID)中的样本,检查了沿美国六个州部分地区道路安装的使用中终端终端的状况。两个微小和三个严重损坏的ET-Plus系统的有限元(FE)模型,美国道路上常用的能量吸收护栏末端终端,是开发的。为了评估损坏的ET-Plus系统的性能,根据国家合作公路研究计划(NCHRP)350,测试条件3-30,我们使用车辆损坏的ET-Plus模型进行了碰撞模拟。
结果:在我们调查的1000个在职终端案例中,73%未受损,18%有轻微伤害,8%有重大损失。平均车辆减速率的增加,最大车辆偏航角,相对于未损坏的ET-Plus端端子的冲击,在模拟的ET-Plus端端子的冲击中观察到车辆局部变形。对于一个损坏的ET-Plus,观察到二次碰撞。总的来说,我们发现,与未损坏的终端相比,损坏的终端通常会增加碰撞的严重性。
结论:本研究的结果指出,需要对终端终端进行在役性能评估以及适当的维护和修理实践。本研究中开发的仿真模型可进一步用于调查碰撞情况下的器件性能,这些碰撞情况在物理上无法测试和调查站点特性对器件性能的影响。仿真模型还可以补充碰撞测试,以证明新的硬件设计。
OBJECTIVE: Guardrail end terminals are designed to gradually decelerate vehicles during impact and protect vehicle occupants from severe injuries. It has been observed that some in-service end terminals are damaged, and it is unclear if their safety performance is still acceptable. The objectives of this study were to examine the conditions of in-service end terminals, and to evaluate the performance of damaged relative to undamaged end terminals in simulated impacts.
METHODS: Common damage patterns of guardrail end terminals were investigated by using post-crash pictures collected from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS). Conditions of in-service end terminals mounted along roads in portions of six U.S. states were examined by using a sample from the second Strategic Highway Research Program-Roadway Information Database (SHRP2-RID). Finite Element (FE) models of two minorly and three severely damaged ET-Plus systems, a commonly used energy-absorbing guardrail end terminal along U.S. roads, were developed. To evaluate the performance of the damaged ET-Plus systems, we performed impact simulations with vehicle-to-damaged ET-Plus models according to the National Cooperative Highway Research Program (NCHRP) 350, test conditions 3-30.
RESULTS: Of the 1000 in-service end terminal cases we investigated, 73% were undamaged, 18% had minor damage, and 8% had major damage. Increases in the average vehicle deceleration rates, maximum vehicle yaw angles, and vehicle local deformations were observed in simulated impacts with damaged ET-Plus end terminals relative to impacts with undamaged ET-Plus end terminals. For one damaged ET-Plus, a secondary collision was observed. Overall, we found that the damaged end terminals usually increased collision severity when compared with undamaged end terminals.
CONCLUSIONS: The findings of this study point out the need for in-service performance evaluations and proper maintenance and repair practices of end terminals. The simulation models developed in this study could be further employed to investigate device performance in crash situations that are physically impractical to test and investigate the effects of site characteristics on device performance. The simulation models could also supplement crash tests to certify new hardware designs.