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Autofoam- Chassis Foaming
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<blockquote data-quote="LCP" data-source="post: 185239" data-attributes="member: 2424"><p>Aha... Bundy, yes, you have a point there, but here's my take... crumple zone crumpling too fast... that will cause it to crumple too much meaning that any structure behind it will be structurally affected too, that will cause other complications instead... body parts and limbs getting trapped due to deformed passenger cell.</p><p> </p><p>Longer time to crumple, here are some calculations:</p><p> </p><p>Let's say the crumple zone takes 0.2 sec to crumple (and come to complete stop), and you are going at 72km/h (20metre/sec), it means your deceleration rate is 100metre/sec/sec (sorry, dunno how to type mathematical notation here). That's quite bad to your body.</p><p> </p><p>Let's say, in another case, the crumple zone now takes 0.25sec to crumple and come to a complete stop, and you are going at 72km/h (20metre/sec), your deceleration rate is now only 80metre/sec/sec. That's quite a bit less (20%), meaning more chance of getting out alive and with less injury.</p><p> </p><p>Let's summarise the figures (all assuming 72km/h initial speed):</p><p> </p><p>Crumple time: 0.01sec (sure die...)</p><p>Deceleration rate: 2000metre/sec/sec</p><p> </p><p>Crumple time: 0.1sec</p><p>Deceleration rate: 200metre/sec/sec</p><p> </p><p>Crumple time: 0.2sec</p><p>Deceleration rate: 100metre/sec/sec</p><p> </p><p>Crumple time: 0.25sec</p><p>Deceleration rate: 80metre/sec/sec</p><p> </p><p>Crumple time: 0.5sec</p><p>Deceleration rate: 40metre/sec/sec</p><p> </p><p>Crumple time: 1.0sec (not practical already)</p><p>Deceleration rate: 20metre/sec/sec</p><p> </p><p>Crumple time: 2.0sec (not practical already)</p><p>Deceleration rate: 10metre/sec/sec</p><p> </p><p>Crumple time: 5.0sec (I think braking from 72 to 0km/h also less than that)</p><p>Deceleration rate: 4metre/sec/sec</p><p> </p><p>The above listing shows that it is not possible to die from hard braking due to relatively low deceleration rate when compared to an impact...</p><p> </p><p>On the other hand, parts that cannot crumple will pose another problem altogether, it will be equivalent to extremely short crumple time, refer to the above listing.</p><p> </p><p>So, the foam will extend the crumple time a little, and at the same time not rigid enough to prevent full crumpling (it will still crumple all the way), that should achieve the aim of extending the crumpling time and reduce the deceleration force, but not by large percentage, just that I don't have the datasheet with me now...</p></blockquote><p></p>
[QUOTE="LCP, post: 185239, member: 2424"] Aha... Bundy, yes, you have a point there, but here's my take... crumple zone crumpling too fast... that will cause it to crumple too much meaning that any structure behind it will be structurally affected too, that will cause other complications instead... body parts and limbs getting trapped due to deformed passenger cell. Longer time to crumple, here are some calculations: Let's say the crumple zone takes 0.2 sec to crumple (and come to complete stop), and you are going at 72km/h (20metre/sec), it means your deceleration rate is 100metre/sec/sec (sorry, dunno how to type mathematical notation here). That's quite bad to your body. Let's say, in another case, the crumple zone now takes 0.25sec to crumple and come to a complete stop, and you are going at 72km/h (20metre/sec), your deceleration rate is now only 80metre/sec/sec. That's quite a bit less (20%), meaning more chance of getting out alive and with less injury. Let's summarise the figures (all assuming 72km/h initial speed): Crumple time: 0.01sec (sure die...) Deceleration rate: 2000metre/sec/sec Crumple time: 0.1sec Deceleration rate: 200metre/sec/sec Crumple time: 0.2sec Deceleration rate: 100metre/sec/sec Crumple time: 0.25sec Deceleration rate: 80metre/sec/sec Crumple time: 0.5sec Deceleration rate: 40metre/sec/sec Crumple time: 1.0sec (not practical already) Deceleration rate: 20metre/sec/sec Crumple time: 2.0sec (not practical already) Deceleration rate: 10metre/sec/sec Crumple time: 5.0sec (I think braking from 72 to 0km/h also less than that) Deceleration rate: 4metre/sec/sec The above listing shows that it is not possible to die from hard braking due to relatively low deceleration rate when compared to an impact... On the other hand, parts that cannot crumple will pose another problem altogether, it will be equivalent to extremely short crumple time, refer to the above listing. So, the foam will extend the crumple time a little, and at the same time not rigid enough to prevent full crumpling (it will still crumple all the way), that should achieve the aim of extending the crumpling time and reduce the deceleration force, but not by large percentage, just that I don't have the datasheet with me now... [/QUOTE]
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