Autofoam- Chassis Foaming

[DChong]

Hi Slider,

Can u call "something" that can hold your whole weight, infact a 135 kg guy can stand on it without compressing it..... Soft?

Yet this "something" can be pierced through with your finger.

And it is ultra-lightweight.

This is exactly what we all are looking for ....something Rigid enuff to increase torsional & bending rigidity yet Pliant enuff to absorb energy.

This "Something" is called AutoFoam.....the Hidden Advantage.

ps, Fabian, wglee, LCP, the New AutoFoam Race is here.

Cheers,

DChong
KL AUTO
www.autofoam.com.my

 

[Slide]

DChong,
Just one question, is it stronger than the metal in a car?
I just need a bit more convincing before i do this mod....

 

[fabianyee]

DChong,
Just one question, is it stronger than the metal in a car?
I just need a bit more convincing before i do this mod....

Don't quote me on this but IMHO, it won't be stronger and it shouldn't be, but it reduces the chassis flexing by filling up the critical cavities. It should still collapse in the event of a collision.

 

[dvng]

do not confused strength and stiffness. High strength does not relate to high stiffness. EG. high strength materials gives smaller x-sections hence lighter but stiffness are sacrificed. Low strength material can give high stiffness..heavier sections. 1mm thk of high strength plate is less stiff than 2mm thk low strength plate. Foaming a chassis will increase the stiffness slightly since the foam substance has lower modulus of elasticity but the a solid section is significantly stiffer than a hollow section..but then you also to look at torsional and bending stiffness which dictates flex stiffness..this is not to be confused with axial capacity or buckling capacity..this are also affected by the effective length of the cross section..zzzzzzzzzz..guys this whole issue of stiffness, strength, buckling, torsional rigidity is very complex. You also have to look at the design of the chassis itself and how the stiffness are derived on the whole. Stiffening at certain portion of the chassis will increase stiffness but then you also have to look at where it is stiffened..the further from the centre of inertia of the chassis the better increased you will gain. Beware of claims by the manufacturer unless he is a structural engineer like me..as for whether foaming is effective or not..i leave it to you entirely..

 

[Slide]

dvng,
Sounds like you've just been selected to be the official rep to go and check this out for the rest of us!

 

[ALBundy]

If I remembered correctly, the time taken for the crumple zone to crumple was extended a bit with the foam, in my opinion this translated to a longer time to disperse the crash impact meaning lesser stress on the occupants during the crash.

LCP, i thought its the other way round. Crumple zones that collapse quicker would be able to absorb the impact force better and hence more safety to the passengers? Take it to the extreme, say you have reinforced it to the limit where it would take aeons to crumple...what would happened then??

 

[pussy]

all e39's came with lower sill, a pillar foamed.. the foam is brittle, but solid in strength..

how i know ? , go see half-cut's e39's...

even my e30 is foamed in the bottom sill.... after 3 days.. the lowered suspension could not take it..

becareful where you foam, unlike me..one word-messy..

 

[LCP]

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...

 

[LCP]

So, I remembered someone's (sorry, can't recall who) signature that quoted Jeremy Clarkson's "Speed has never killed anyone, suddenly becoming stationary is what gets you" (or something like that)... that statement makes lotsa sense....

 

[LCP]

Err, pussy, care to explain a bit more detail why the suspension could not take it...

 

[LCP]

I forgot to mention that the deceleration rates above assume a linear rate, if the rate is non-linear (eg. too high in the beginning, low in the end), serious injury and death can still happen.

 

[DanPromote]

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...

If it's your time to go... nothing u can do to stop it.

 

[fandango]

i also have a 92 corolla that've i've foamed. used AFRace on the sills and normal AF on the b-pillars. i can 'feel' the chassis much better, and the suspension just works better. overall a good investment, i feel, given that the car is already 14 years old.

 

[DChong]

Hi LCP,

Do u own the Satria or the GTI ? Its been a long time since & great to hear u r still enjoying AutoFoam.

Pussy, your car is Not treated with AutoFoam, right ?

AutoFoam Will Definitely Improve Handling & Ride Comfort . It would even help stiff Sports suspension feel more comfortable.

Kindly Do Not associate DIY, industrial type foam with AutoFoam. They are not the same thing.

fandango, i forgot u are also a Beemer fan.

Cheers,

DChong
KL AUTO
www.autofoam.com.my

 

[LCP]

Desmond, I am the green Satria owner...

 

[ALBundy]

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...

LCP, basically the formula is famous Newtonian Law, F=M X A , in this case A is deceleration ( V - U) / T. So the bigger the T value, the impact force is lessen.

But this is a simplified situation, there is a lot more to it and pretty complex too

 

[LCP]

Correct. Actual real life crash situation is very complex...

 

[LCP]

Guys, found the URL for Dow's foam, there are two types: acoustical and structural... have a browse on the data... too bad Dow doesn't sell to end/retail customers, but to car manufacturers only, unless you wanna buy by the barrels...

http://automotive.dow.com/materials/products/betafoam/product.htm

 

[DanPromote]

also one important thing, some are flamable. You can find many of those at the hardware stores but don't use it for your car.

 

[doramon]

so verdict can use la