根据美国国家安全委员会统计发布的数据表明，自2007年以来，在美国的因交通事故而死亡的机率得到了大幅的下降。其最大的功臣就是“汽车碰撞测试”所带来的成果，汽车制造商通过运用这一系列的测试数据不断来提供汽车的安全性能。

现如今，测试和工具开发团体的碰撞测试的方向正不断向如何防撞扩展。由SAE编辑们举办的《碰撞测试的未来》系列在线技术研讨会中，4名行业专家就防撞和碰撞防护领域的一些最新进展展开了讨论。点击此处跳转至在线技术研讨会页面。（注册后您可以在线观看视频及下载相关PPT,但您观看视频时可能需要使用VPN。）

如何防撞是美国公路安全保险研究所(IIHS)的重点研究发展领域，最近他们特地建造了一个专门用于研究如何防撞的试验场，用于下一阶段的测试。

IIHS高级研究工程师Becky Mueller表示：“我们未来的所有研究将围绕着以下两大方针展开，一是，如何尽可能的避免事故的发生？二是，那事故万一真的发生了，我们又怎么样才能将其严重程度降到最低？”

在2013年，IIHS率先推出一项“正向防撞测试”。任何一款车辆若想获得“顶级安全+(Top Safety Pick +)”奖项殊荣，必须具备防撞技术，并在一系列的测试取得高分。

Mueller补充道，目前IIHS也在针对如何减少夜间的碰撞机率不断努力。IIHS计划在未来的一年左右，推出一项有关“汽车前照灯”的新评价项目，驾驶员视野及防眩光将是主要考核课目。

尽管防撞是眼下的热门话题，但车辆的耐撞性依然是评价车辆安全性能的核心重点。设计工具提供商为了帮助OEM提高车辆的性能，也正在从各个方面进行研究并提出了相关策略。汽车轻量化概念的提出，目的是在于在提高汽车的燃油经济性、降低汽车制造成本，但是这一切对于安全性能来说着实是一大挑战。

“安全方面的政策越来越严，但要如何在有限的预算内满足这些要求更是难上加难”，Simulia战略项目总监Marc Schrank表示，“但越来越多的全新轻量化技术在提高安全性能方面也起到了重要的作用。”

高强度钢、铝、镁、碳纤维复合材料的应用，使得设计变得越来越困难，因为仿真工具无法精确模拟预估碰撞后的情况。但精确的仿真预判对于汽车制造商来说异常重要，因为精确仿真的存在他们可以直接在早期的量产车上进行测试，而不必专门为此制造一辆原型车。

“碳纤维是一种很有意思的材料，它在给我带来机遇的同时，也给带来了挑战，” Schrank表示。“它能够吸收大量的能量，但回弹性往往却都不佳。形变表现与金属相比简直是鲜明的对比。”

近年来，虚拟测试能够检测的项目数量迅速增加，与此同时测试时间却正在大幅度的缩短，这使得我们能够获得更真实的数据，提高迭代速度。

“测试速度越来越快，模型尺寸也明显变大了，” Altair的高级业务发展总监Jean Michel Terrier表示。“现在一天之内就可以完成500多万个元素的碰撞仿真测试。”

尽管仿真测试能给我们带来许多好处，但在线研讨会的专家们也指出，真实测试依然是必须的。SEA公司运用自动驾驶汽车来再现真实碰撞情况，而工作人员则负责设计各种非常具体的碰撞情况。

“自动驾驶汽车可以实现那些传统碰撞测试所不能进行的测试，” SEA车辆动力学总监Gary J. Heydinger表示。“譬如我们可以开展在实验室里做不了的满油测试，又如休闲越野车常见的翻车等复杂测试。”

作者：Terry Costlow
来源：SAE《汽车工程杂志》
翻译：SAE上海办公室

Crash testing advances on many fronts

Traffic fatalities have declined significantly over the last several years, but the U.S. is on track to have its deadliest year since 2007, according to the National Safety Council. That’s shining the spotlight on crash testing, which helps automakers create the safest vehicles possible.

Crash-testing research being done by testing groups and tool developers is extending its reach to crash avoidance. Some of the latest developments in collision avoidance and protection were recently explored by four industry experts in "The Future of Crash Testing" Technical Webinar Series from the Editors of SAE, which isnow available for on-demand viewing.

Avoiding crashes is a critical factor for development at the Insurance Institute for Highway Safety. The group recently built a crash avoidance dome where next level testing will occur.

“We want to prevent crashes when possible, and to reduce the severity when collisions occur,” said Becky Mueller, Senior Research Engineer at IIHS. “We’re taking a twofold approach on all our future research.”

IIHS introduced a frontal crash prevention test in 2013. Prevention is now a factor in its Top Safety Pick Plus award, which requires vehicles to have technology for avoiding crashes and good rankings on all crash tests.

There’s also an effort to reduce collisions that occur at night, Mueller added. IIHS is preparing a new evaluation for headlights, looking at vision and glare. A new ratings program is expected “in a year or so,” she said.

Though crash prevention has become a hot topic, crash worthiness remains a central factor in the push for improved safety. Design tool providers are working on a range of strategies that will help automakers build safe vehicles. Reducing weight to improve fuel consumption is a challenge for safety, as is keeping costs in check.

“Safety regulations are becoming more strict; one issue is meeting those requirements within cost budgets,” said Marc Schrank is Director of Strategic Projects at Simulia. “Secondly, the increase in the number of new lightweighting technologies plays a substantial role in safety.”

Changes in materials such as high-strength steel, aluminum, magnesium, and composites like carbon fiber are making it more difficult for design and simulation tools to precisely predict what will happen in collisions. High levels of predictiveness are important because they let automakers run tests on early production vehicles instead of creating prototypes to determine whether simulations are accurate.

“Carbon fiber is an interesting material that presents opportunity and challenges,” Schrank said. “It has high energy absorption, but composites have little resiliency. Deformation is in stark contrast to metal’s performance.”

The number of factors that can be included in virtual tests has soared in recent years while the time needed to run tests has fallen. That makes for more realistic tests and more iterations.

“There’s significantly more speed and increased model size,” said Jean Michel Terrier, Altair’s Senior Business Development Director. “Now there are over 5 million elements and crash simulations can run in one night.”

While simulations bring significant benefits, webinar speakers noted that real world tests are still needed. SEA Ltd. specializes in reproducing real-world crashes, using autonomous vehicles that let employees cause very specific types of crashes.

“Autonomous vehicle controls permit crash testing that is not possible using traditional crash tests,” said Gary J. Heydinger, Director of Vehicle Dynamics at SEA. “We do things like full fuel testing that you can’t do in a lab. We can also do complex tests like recreational off-highway vehicle rollovers, which are common for these vehicles.”