Editing Crumple zone (section)

{{Short description|Structural feature used in vehicles}}
{{Redirect|Crush zone|the geopolitical concept|Shatter belt (geopolitics)}}
[[File:Strefa zgniotu w tescie zderzeniowym.jpg|thumb|right|A [[crash test]] illustrates how a crumple zone absorbs energy from an impact.]]
[[Image:Impact Attenuator In Auckland.jpg|thumb|right|Road Maintenance Truck Impact Attenuator, [[Auckland]], New Zealand]]
[[File:JR-East-E217-Side.jpg|thumb|right|Extent of the crumple zones (blue) and the driver's safety cell (red) of an [[E217 series]] train]]
[[Image:Verkehrsunfall1.jpg|thumb|right|The crumple zone on the front of these cars absorbed the impact of an offset head-on collision.]]

'''Crumple zones''', '''crush zones'''<ref name=HSWcrumple/> or '''crash zones''' are a structural safety feature used in vehicles, mainly in automobiles, to increase the time over which a change in [[velocity]] (and consequently [[momentum]]) occurs from the impact during a collision by a controlled [[deformation (engineering)|deformation]]; in recent years, it is also incorporated into trains and railcars.<ref name=machinedesign>{{cite web |first=Paul |last=Dvorak |url=http://machinedesign.com/article/will-the-crash-zone-crumple-fea-tells-1106 |title=Will the crash zone crumple? FEA tells |publisher=Machine Design |date=2003-11-06 |access-date=2016-07-17 |url-status=dead |archive-url=https://web.archive.org/web/20130318082440/http://machinedesign.com/article/will-the-crash-zone-crumple-fea-tells-1106 |archive-date=2013-03-18 }}</ref><ref>{{cite web |last=Grabianowski |first=Ed |url=https://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/crumple-zone.htm#pt2 |title=How Crumple Zones Work – Design Compromises |website=[[HowStuffWorks]] |publisher=[[System1]] |date=2008-08-11 |access-date=2016-07-17}}</ref><ref>{{cite web|url=http://www.plastics-car.com/crumplezone |title=Physics in the Crumple Zone Demonstrate How Less Stiff Materials, Like Plastic, Can Help Prevent Injury and Save Lives |website=Automotive Plastics |access-date=2016-07-17 |url-status=usurped |archive-url=https://web.archive.org/web/20170316063649/http://www.plastics-car.com/crumplezone |archive-date=2017-03-16}}</ref><ref>{{cite web|url=http://www.inds.co.uk/education/wdss/Crumple_zones.pdf |archive-url=https://web.archive.org/web/20070306021005/http://www.inds.co.uk/education/wdss/Crumple_zones.pdf |url-status=dead |archive-date=2007-03-06 |title=Investigating how crumple zones incorporated into modern trains make them much safer in collisions |access-date=2016-07-17}}</ref>

Crumple zones are designed to increase the time over which the total force from the change in [[momentum]] is applied to an occupant, as the average [[force]] applied to the occupants is inversely related to the time over which it is applied. The physics involved can be expressed by the equation:

<math display="block">F_\text{avg}\Delta t = m\Delta v </math>

where <math>F</math> is the force, <math>t</math> is the time, <math>m</math> is the mass, and <math>v</math> is the velocity of the body. In [[SI]] units, [[force]] is measured in [[Newton (unit)|newtons]], time in seconds, mass in [[kilogram]]s, velocity in [[metres per second]], and the resulting [[Impulse (physics)|impulse]] is measured in [[newton second]]s (N⋅s).

Typically, [[crumpling|crumple]] zones are located in the front part of the vehicle, to absorb the impact of a [[head-on collision]], but they may be found on other parts of the vehicle as well. According to a British Motor Insurance Repair Research Centre study of where on the vehicle impact damage occurs, 65% were front impacts, 25% rear impacts, 5% left-side, and 5% right-side.<ref>{{cite book |first1=A. |last1=Robinson |first2=W. A. |last2=Livesey |title=The Repair of Vehicle Bodies |page=406 | edition = 5th |year= 2006 | publisher = Butterworth-Heinemann | isbn=978-0-7506-6753-1}}</ref> Some racing cars use aluminium, composite/carbon fibre honeycomb, or energy absorbing foam<ref>{{cite web|url=https://www.fsaeonline.com/page.aspx?pageid=193613e4-fff1-4ea9-97ec-eb1c07fbe3c0 |title=Standard Impact Attenuator Design |publisher=Formula SAE |access-date=2016-07-17}}</ref><ref>{{cite web|url=http://www.formula-seven.com/shop-products/impact-attenuator-t-12/ |title=Standard Impact Attenuator |publisher=Formula Seven |access-date=2016-07-17}}</ref> to form an [[impact attenuator]] that dissipates crash energy using a much smaller volume and lower weight than road car crumple zones.<ref name=HSWcrumple>{{cite web |last=Grabianowski |first=Ed |url=http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/crumple-zone.htm |title=How Crumple Zones Work |website=[[HowStuffWorks]] |publisher=[[System1]] |date=2008-08-11 |access-date=2011-09-23}}</ref> Impact attenuators have also been introduced on highway maintenance vehicles in some countries. 

On September 10, 2009, the [[ABC News (United States)|ABC News]] programs ''[[Good Morning America]]'' and ''[[ABC World News|World News]]'' showed a U.S. [[Insurance Institute for Highway Safety]] [[crash test]] of a 2009 [[Chevrolet Malibu]] in an offset head-on collision with a 1959 [[Chevrolet Bel Air]] sedan. It dramatically demonstrated the effectiveness of modern car safety design over 1950s design, particularly of rigid passenger safety cells and crumple zones.<ref>{{cite web|last=Stark |first=Lisa |url=https://abcnews.go.com/Travel/technology-reduces-severity-car-crashes-fatalities-injuries/story?id=8523234&page=1 |title=Highway Safety Exclusive: Car Crashes, Travel Deaths Prevented by Technology |work=ABC News |location=United States<!--disambiguate from Australia--> |date=2009-09-10 |access-date=2011-09-23}}</ref><ref>{{cite web|last=Neff |first=John |url=http://www.autoblog.com/2009/09/26/pics-aplenty-iihs-reveals-before-and-after-of-malibu-bel-air-cr |title=Pics Aplenty: IIHS reveals before and after of Malibu/Bel Air crash |website=Autoblog |access-date=2011-09-23}}</ref>