根據(jù)美國(guó)國(guó)家安全委員會(huì)統(tǒng)計(jì)發(fā)布的數(shù)據(jù)表明，自2007年以來(lái)，在美國(guó)的因交通事故而死亡的機(jī)率得到了大幅的下降。其最大的功臣就是“汽車碰撞測(cè)試”所帶來(lái)的成果，汽車制造商通過(guò)運(yùn)用這一系列的測(cè)試數(shù)據(jù)不斷來(lái)提供汽車的安全性能。
現(xiàn)如今，測(cè)試和工具開(kāi)發(fā)團(tuán)體的碰撞測(cè)試的方向正不斷向如何防撞擴(kuò)展。由SAE編輯們舉辦的《碰撞測(cè)試的未來(lái)》系列在線技術(shù)研討會(huì)中，4名行業(yè)專家就防撞和碰撞防護(hù)領(lǐng)域的一些最新進(jìn)展展開(kāi)了討論。點(diǎn)擊此處跳轉(zhuǎn)至在線技術(shù)研討會(huì)頁(yè)面。（注冊(cè)后您可以在線觀看視頻及下載相關(guān)PPT,但您觀看視頻時(shí)可能需要使用VPN。）
如何防撞是美國(guó)公路安全保險(xiǎn)研究所(IIHS)的重點(diǎn)研究發(fā)展領(lǐng)域，最近他們特地建造了一個(gè)專門用于研究如何防撞的試驗(yàn)場(chǎng)，用于下一階段的測(cè)試。
IIHS高級(jí)研究工程師Becky Mueller表示：“我們未來(lái)的所有研究將圍繞著以下兩大方針展開(kāi)，一是，如何盡可能的避免事故的發(fā)生？二是，那事故萬(wàn)一真的發(fā)生了，我們又怎么樣才能將其嚴(yán)重程度降到最低？”
在2013年，IIHS率先推出一項(xiàng)“正向防撞測(cè)試”。任何一款車輛若想獲得“頂級(jí)安全+(Top Safety Pick +)”獎(jiǎng)項(xiàng)殊榮，必須具備防撞技術(shù)，并在一系列的測(cè)試取得高分。
Mueller補(bǔ)充道，目前IIHS也在針對(duì)如何減少夜間的碰撞機(jī)率不斷努力。IIHS計(jì)劃在未來(lái)的一年左右，推出一項(xiàng)有關(guān)“汽車前照燈”的新評(píng)價(jià)項(xiàng)目，駕駛員視野及防眩光將是主要考核課目。
盡管防撞是眼下的熱門話題，但車輛的耐撞性依然是評(píng)價(jià)車輛安全性能的核心重點(diǎn)。設(shè)計(jì)工具提供商為了幫助OEM提高車輛的性能，也正在從各個(gè)方面進(jìn)行研究并提出了相關(guān)策略。汽車輕量化概念的提出，目的是在于在提高汽車的燃油經(jīng)濟(jì)性、降低汽車制造成本，但是這一切對(duì)于安全性能來(lái)說(shuō)著實(shí)是一大挑戰(zhàn)。
“安全方面的政策越來(lái)越嚴(yán)，但要如何在有限的預(yù)算內(nèi)滿足這些要求更是難上加難”，Simulia戰(zhàn)略項(xiàng)目總監(jiān)Marc Schrank表示，“但越來(lái)越多的全新輕量化技術(shù)在提高安全性能方面也起到了重要的作用。”
高強(qiáng)度鋼、鋁、鎂、碳纖維復(fù)合材料的應(yīng)用，使得設(shè)計(jì)變得越來(lái)越困難，因?yàn)榉抡婀ぞ邿o(wú)法精確模擬預(yù)估碰撞后的情況。但精確的仿真預(yù)判對(duì)于汽車制造商來(lái)說(shuō)異常重要，因?yàn)榫_仿真的存在他們可以直接在早期的量產(chǎn)車上進(jìn)行測(cè)試，而不必專門為此制造一輛原型車。
“碳纖維是一種很有意思的材料，它在給我?guī)?lái)機(jī)遇的同時(shí)，也給帶來(lái)了挑戰(zhàn)，” Schrank表示。“它能夠吸收大量的能量，但回彈性往往卻都不佳。形變表現(xiàn)與金屬相比簡(jiǎn)直是鮮明的對(duì)比。”
近年來(lái)，虛擬測(cè)試能夠檢測(cè)的項(xiàng)目數(shù)量迅速增加，與此同時(shí)測(cè)試時(shí)間卻正在大幅度的縮短，這使得我們能夠獲得更真實(shí)的數(shù)據(jù)，提高迭代速度。
“測(cè)試速度越來(lái)越快，模型尺寸也明顯變大了，” Altair的高級(jí)業(yè)務(wù)發(fā)展總監(jiān)Jean Michel Terrier表示。“現(xiàn)在一天之內(nèi)就可以完成500多萬(wàn)個(gè)元素的碰撞仿真測(cè)試。”
盡管仿真測(cè)試能給我們帶來(lái)許多好處，但在線研討會(huì)的專家們也指出，真實(shí)測(cè)試依然是必須的。SEA公司運(yùn)用自動(dòng)駕駛汽車來(lái)再現(xiàn)真實(shí)碰撞情況，而工作人員則負(fù)責(zé)設(shè)計(jì)各種非常具體的碰撞情況。
“自動(dòng)駕駛汽車可以實(shí)現(xiàn)那些傳統(tǒng)碰撞測(cè)試所不能進(jìn)行的測(cè)試，” SEA車輛動(dòng)力學(xué)總監(jiān)Gary J. Heydinger表示。“譬如我們可以開(kāi)展在實(shí)驗(yàn)室里做不了的滿油測(cè)試，又如休閑越野車常見(jiàn)的翻車等復(fù)雜測(cè)試。”
作者：Terry Costlow
來(lái)源：SAE《汽車工程雜志》
翻譯：SAE上海辦公室
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.”
IIHS將會(huì)不斷改善碰撞測(cè)試，直到能夠100%避免碰撞事故的發(fā)生。