Impact absorbing door protection

[John Cassidy]

I realize that the WRC lads probably have custom molded energy absorbing door panels and custom cage design to accomodate, but is there something we could install in our cars(retrofit) that would offer us at least some impact absorption?

Two co-drivers out with broken pelvis' this season in the WRC due to side impacts. The Lovell/Freeman impact was a side impact. Beef impact was side. Sprongls had a nasty side impact at STPR a couple years ago in the EVO.

We all know we can't escape the inherent dangers of side impacts in a race car based on a road shell, but it would be nice to have the option to do something between the door and the cage.

Regards, John

[John Sundelin]

I am pretty sure that Patrick Pivato is alive because of that side impact protection upgrades that they put on the WRC cars earlier this year (there's a thread on that somewhere in the car construction forum with pictures). I am not sure if the Stobart team had the fancy new seats, but from the description of the accident and the picture I saw, he's very fortunate to still be here.

The WRC cars do use a commercially available aluminum honeycomb with graphite-epoxy reinforcement. Though I imagine it's quite expensive to have a custom door guard made, a set of square shaped items that provide pretty decent protection probably wouldn't be too outlandish.

--
John

[Foghorn]

The Nascar types seem to think that the "safer barriers" installed around tracks are quite effective in reducing the severity of impact crashes into the walls. I don't have any idea about how they are constructed or of what material, but could there be any relevance here in an application into rallycars themselves?

[randyzimmer]

Because part of the brief on the walls was to keep the car "planted " in the wall, there are no doubt, better materials and use.
Check here:
http://www.freepatentsonline.com/6926461.html
http://en.wikipedia.org/wiki/SAFER_barrier


Cellofoam — This is an encapsulated polystyrene barrier—a block of plastic foam encased in polyethylene.
Polyethylene Energy Dissipation System (PEDS) — This system uses small polyethylene cylinders inserted inside larger ones. Designers of PEDS believe the system increases the wall's ability to withstand crashes of heavy race cars.

Looks like stuffing compressible stuff inside a tough containment envelope is the trick.
Some of the materials like the Celofoam may have been looked at because of cost factors of ringing so many tracks. A better foam (like the beads for helmets) may have not been tested for the walls.

[Jens]

You guys are getting closer and closer to what I told you years ago.....

AFFF filled cocoons.

You could slow down rally, but NOooooooooooooo. That wouldn't be racing, ya'll say.

[starion887]

Because part of the brief on the walls was to keep the car "planted " in the wall, there are no doubt, better materials and use.
Check here:
http://www.freepatentsonline.com/6926461.html
http://en.wikipedia.org/wiki/SAFER_barrier


Cellofoam — This is an encapsulated polystyrene barrier—a block of plastic foam encased in polyethylene.
Polyethylene Energy Dissipation System (PEDS) — This system uses small polyethylene cylinders inserted inside larger ones. Designers of PEDS believe the system increases the wall's ability to withstand crashes of heavy race cars.

Looks like stuffing compressible stuff inside a tough containment envelope is the trick.
Some of the materials like the Celofoam may have been looked at because of cost factors of ringing so many tracks. A better foam (like the beads for helmets) may have not been tested for the walls.

Plus controlling where the 'stuff' goes during impact is important. It can't move/squirt towards the occupants or other injuries can result. Too bad water is so heavy.

Mark B.

[ajax]

McMaster-Carr has Aluminum crush media. If you wanted to fill your whole door with it it might get a little expensive, a rough guess of about $200/door depending on how you used it. That is what they used on the front of our FSAE car at MTU. I don't really have any experience with the stuff but destroying things in the name of science is always awesome.

[RallyTruck]

I have been thinking of spraying 2lb foam inside my doors. I'm in the spray business and we use this stuff to line all kinds of things. A 3" 1'x1' piece of 2lb foam can't be crushed by driving an f250 over it. And it only weighs 2lbs! This was just my own little test, not an actual ASTM. We are starting to install this stuff in buildings here in CA for earthquake protection. Don't confuse this with the "foam in a can" from HD. That is .5lbs open cell foam. 2lb is only available commercially and is labeled as closed foam. So by the time the expansion is complete inside a door you will have about 6" of protection encapsulated by a steel door. The PSI of destruction or failure is now a number much greater than that 1'x1' piece because of the encapsulation and area sprayed. I am going to get a door from a wrecking yard and do a sample run in the up coming months. I originally put this stuff in a hold of a fishing vessel. The owner said he wanted to drop a 200lb tuna from 100' in the air and not have it go through the bottom of the boat. We were successful at accomplishing this. So why not Rally cars! The cost would be about $300 per door. -not a bad price when talking about your life! The only drawback I can see, is that you will have to change out your windows because you would no longer be able to roll them down. This process would also require a little sheet metal work to protect your locking mechanism. Other than that, if any foam came out of the door during impact, I doubt that it would hurt too much!

Anyway, I'll let you all know what I come up with!

[randyzimmer]

How'd the tuna feel?
If he bounced back up and hit the water swimming,
I'd say you were on to something.

[John Cassidy]

Jeff, keep us posted on the experiment. Always looking for cheap methods to increase safety. Thanks to everyone for chiming in.

Cheers! John

[ajax]

A 3" 1'x1' piece of 2lb foam can't be crushed by driving an f250 over it. And it only weighs 2lbs! This was just my own little test, not an actual ASTM.

Ha, if it was, somebody at ASTM was drinking on the job.

Let me know if you'd like some help with this. I'm not a test engineer (fingers crossed to get me a job doing this at honda) but this is definitely the sort of thing that interests me. Besides, I just graduated and I kinda miss doing the purely scientific things already.

Paul

[starion887]

I have been thinking of spraying 2lb foam inside my doors. I'm in the spray business and we use this stuff to line all kinds of things. A 3" 1'x1' piece of 2lb foam can't be crushed by driving an f250 over it. And it only weighs 2lbs! This was just my own little test, not an actual ASTM. We are starting to install this stuff in buildings here in CA for earthquake protection. Don't confuse this with the "foam in a can" from HD. That is .5lbs open cell foam. 2lb is only available commercially and is labeled as closed foam. So by the time the expansion is complete inside a door you will have about 6" of protection encapsulated by a steel door. The PSI of destruction or failure is now a number much greater than that 1'x1' piece because of the encapsulation and area sprayed. I am going to get a door from a wrecking yard and do a sample run in the up coming months. I originally put this stuff in a hold of a fishing vessel. The owner said he wanted to drop a 200lb tuna from 100' in the air and not have it go through the bottom of the boat. We were successful at accomplishing this. So why not Rally cars! The cost would be about $300 per door. -not a bad price when talking about your life! The only drawback I can see, is that you will have to change out your windows because you would no longer be able to roll them down. This process would also require a little sheet metal work to protect your locking mechanism. Other than that, if any foam came out of the door during impact, I doubt that it would hurt too much!

Anyway, I'll let you all know what I come up with!

Before you get too far......
1) What is the flammability of this material? Does it ignite easily? Does it support open flame on its own?
2) When exposed to heat, does it emit smoke?

Some quick reading shows that this material requires a fire barrier between it and interior spaces when used in buildlings, and that it does support flame. This very, very, very probably makes it totally unsuitable in enclosed cars. If you put it in a can (like a thin sheet metal can), inside the door, that might be more acceptable. But it would need to not rupture and expose this material to gas and/or flame in a wreck.

Regards,
Mark B.

[BajaBill]

Jeff,
I have plenty of doors (F-150 & Ranger) do you want one?:rolleyes:

Bill Holmes
New & Improved Truck #44

[RallyTruck]

Hi Bill,

Sure...

l'll take a door or two!

Got the front end back on my truck and the motor/trans are done. Now it's time to slap about 5gal of Bondo on the ol broad and I should be ready for 2009!

I'll let you know when I'm up that direction and we'll hook up!

Thanks!

[Josh wimpey]

I have wanted to make something like this for years but not sure where to start. I think it might work best if the impact panel is integrated into the doorcard (maybe carbon/kevlar molded cover) such that it is already in contact with the cage structure at the door bars. Depending on the thickness, you might even be able to retain the stock windows and mechanisms in some vehicles.

Anyone have any insight into what the specifications for the FIA aluminum honeycomb panels are?

Thickness?
Alloy?
Cell size?
Foil thickness?
Density?
Do they also use expanded polystyrene in the voids or sandwiched between honeycomb panels?

Lots of options on these pages...
http://www.plascore.com/honeycomb/aluminum-core.asp


These guys make something called Higrid and claim it is good for impact/crush panels...
http://www.mcgillcorp.com/alcore/products.html

[John Sundelin]

I have wanted to make something like this for years but not sure where to start. I think it might work best if the impact panel is integrated into the doorcard (maybe carbon/kevlar molded cover) such that it is already in contact with the cage structure at the door bars. Depending on the thickness, you might even be able to retain the stock windows and mechanisms in some vehicles.

Anyone have any insight into what the specifications for the FIA aluminum honeycomb panels are?

Thickness?
Alloy?
Cell size?
Foil thickness?
Density?
Do they also use expanded polystyrene in the voids or sandwiched between honeycomb panels?

Lots of options on these pages...
http://www.plascore.com/honeycomb/aluminum-core.asp


These guys make something called Higrid and claim it is good for impact/crush panels...
http://www.mcgillcorp.com/alcore/products.html

If you look in the Group A rules (Appendix J, Article 255), there is a figure (255-14) that shows the specs for the door panels. The fabric they describe is a prepreg that used to be (and maybe still is) made by Axson, though I think it's been superseded by the E644.

I don't think you want to fill the voids. The energy is absorbed when the aluminum buckles, so preventing that might lead to unsatisfactory results.

--
John

[Josh wimpey]

If you look in the Group A rules (Appendix J, Article 255), there is a figure (255-14) that shows the specs for the door panels. The fabric they describe is a prepreg that used to be (and maybe still is) made by Axson, though I think it's been superseded by the E644.

--
John

Well, it looks like the panels are 23mm thick aluminum honeycomb with 1/8" cells plus 3 layers of carbon on each side...But, I have some unanswered questions:

1) What does cel4.5 or 6.35 mean? I assume it has to do with the thickness and/or grade of aluminum used to form the cell walls

1_b) What thickness and grade of aluminum should be used to form the cell walls? Foil thickness? Alloy?

2) What orientation is the honeycomb formed in? Should the "tubes" formed by the cells run parrallel or perpendicular to the expected direction of impact?

Perpendicular being either vertically or horizontally along the plane of the door and impact panel--long tubes

Parallel meaning that the "tubes" run into or out of the passenger compartment--short tubes


3) What considerations should one have regarding the relative shallow impact angle deviation allowance for honeycomb? I have been told by an engineer at an AL-honeycomb manufacturer that the direction of force must be within 20 degrees of perpendicular to prevent cell fold-over.




Anybody seen one of these FIA panels up close or have a cut-away image that might answer some questions very quickly?

[John Sundelin]

Well, it looks like the panels are 23mm thick aluminum honeycomb with 1/8" cells plus 3 layers of carbon on each side...But, I have some unanswered questions:

The facesheet characteristics are important though, so make sure you compare specs if you use something different.


1) What does cel4.5 or 6.35 mean? I assume it has to do with the thickness and/or grade of aluminum used to form the cell walls

1_b) What thickness and grade of aluminum should be used to form the cell walls? Foil thickness? Alloy?

I think it means you can use 1/8, 3/16, or 1/4 in cells. If you are going to have some made, an application engineer at the manufacturer can probably tell you what the best choice is, most likely based on test data. There's a nice writeup here:

http://www.hexcel.com/NR/rdonlyres/96FE250C-7BB1-4295-82C4-461A31CC97A0/0/HexWebHoneycombEnergyAbsorptionBrochure.pdf


2) What orientation is the honeycomb formed in? Should the "tubes" formed by the cells run parrallel or perpendicular to the expected direction of impact?

Perpendicular being either vertically or horizontally along the plane of the door and impact panel--long tubes

Parallel meaning that the "tubes" run into or out of the passenger compartment--short tubes


Somehow the thread we had on this about a year ago got deleted, but somebody convinced me that despite the drawing, you want short tubes.


3) What considerations should one have regarding the relative shallow impact angle deviation allowance for honeycomb? I have been told by an engineer at an AL-honeycomb manufacturer that the direction of force must be within 20 degrees of perpendicular to prevent cell fold-over.

I think the 20 degrees is for the core without facesheet. I actually have a piece of panel on my desk, and I applied a 45 degree load to the end and it didn't buckle. Wrapping the facesheet around so that there is no exposed aluminum like the picture shows should help a lot in this regard.



Anybody seen one of these FIA panels up close or have a cut-away image that might answer some questions very quickly?

Nope, I once priced a set from M-Sport for my Focus and it was so traumatic that I've forgotten what it was.

--
John

[Josh wimpey]

Originally Posted by Josh wimpey http://www.specialstage.com/forums/images/buttons/viewpost.gif (http://www.specialstage.com/forums/showthread.php?p=282085#post282085)
1) What does cel4.5 or 6.35 mean? I assume it has to do with the thickness and/or grade of aluminum used to form the cell walls

I think it means you can use 1/8, 3/16, or 1/4 in cells. If you are going to have some made, an application engineer at the manufacturer can probably tell you what the best choice is, most likely based on test data. There's a nice writeup here:

http://www.hexcel.com/NR/rdonlyres/96FE250C-7BB1-4295-82C4-461A31CC97A0/0/HexWebHoneycombEnergyAbsorptionBrochure.pdf

John

FIA document
http://www.fia.com/resources/documents/1623371895__AppJ_Art_254A.pdf

From what I can tell, the cel 4.5 or 6.1 refers to the density of the panel. A panel with 1/8" cells can have diffeerent densities depending on the thickness for the foil used to form the cells. The PDF you linked to has densities in lb/cuft on page 16. Panels with 1/8" cells are available in various densities and the crush strength is listed for each:

The following are for the standard hexweb product. The cross-web product is stronger and actually increases in crush strength when impacted off-angle from perpendicular...note that 4.5 and 6.1 are available densities just as FIA specifies if my guess about the coding is correct.

Cell size-Alloy-Density Crush Strength in psi
1/8-5052-3.1 130
1/8-5052-4.5 260
1/8-5052-6.1 450
1/8-5052-8.1 750
ALC-1/8-5052-12.0 1450
ALC-1/8-5052-14.5 2100
ALC-1/8-5052-22.1 4100
ALC-1/8-5052-38.0 5650

Big difference in crush strength between 4.5 and 6.1 lb/cuft densities.

Anyone care to wade through the impact calculations for us to figure out if this is appropriate and what thickness of facesheet should be used?

With a proper facesheet, the carbon won't be necessary and it would be much cheaper and easier to make and install panels on a budget. I think this might be quite an inexpensive way of increasing safety. A 4'x8' sheet looks to be roughly $300 (say $400 with shipping if you need it shipped) and could potentially be used for 2-3 vehicles making the per-vehicle cost quite low.

[John Sundelin]

Since I am taking next week off, I'll call the FIA and see what the numbers are supposed to mean. Initially, I thought they might be density also, but the English conversion was just too neat. It could also be a reference to a trade name.

Incidentally, if you don't wrap the facesheet, you need to be very careful about the edges. If you have the misfortune of running into the edge of one of these things at high speed, you'll bleed out externally before the internal trauma that it saved you from would have killed you.

--
John

[Josh wimpey]

OK, so I am moving forward with developing some of these for our VW. If anyone else with a 2-door mk2 VW is interested let me know as it will likely be cheaper to do several sets at the same time.

These will be very nice pieces--professionally molded just like the fancy carbon doorcards in the big-dogs' cars... Hope to have a price estimate by christmas time...

[wvonkessler]

I had a pair of Hexcel skis once. They were awesome.

[C_Eixen]

OK, so I am moving forward with developing some of these for our VW. If anyone else with a 2-door mk2 VW is interested let me know as it will likely be cheaper to do several sets at the same time.

These will be very nice pieces--professionally molded just like the fancy carbon doorcards in the big-dogs' cars... Hope to have a price estimate by christmas time...

I'm definitely interested in seeing the price.

[Josh wimpey]

Just bringing this back from the abyss as I am still interested in making these for our new shell.

[hoche]

I presume the plan would be to gut the doors and run lexan windows?

[BarefootVirgin]

Interested in seeing the cost factor, obviously a good idea. We are running the MK-III but im sure we can do some additional fab if needed.

[Josh wimpey]

I presume the plan would be to gut the doors and run lexan windows?

Nope and nope. Just make enough room for the 1" thick panels...

[biggreen96]

maybe this could be adapted?

http://www.inhabitat.com/2009/11/18/bomb-proof-wallpaper-could-save-you-in-a-natural-disaster/

[Josh wimpey]

Well, the honecomb will already be wrapped in 2 layers of Carbon/kevlar so....

[steve]

Subscribing to this newsletter.


I sat in my Arrow the other day and wondered about this exact topic. There is NO room between the seat and door bar, and NO room between the door bar and the door panel. In fact rolling down the window will be nearly impossible with the door closed it is that tight.

Thinking this may need to fit completely inside the door inner skin and outer skin, with a thin gap in the middle where the window can roll down into.

Keep em coming.

[brian in denver]

http://www.specialstage.com/photopost/uploads/335/impact_door.jpg

[Josh wimpey]

This is exactly what I was thinking of...


http://i817.photobucket.com/albums/zz100/Billb-pics/Eschdorf2010/100_0481.jpg

[Safe Drives]

This is exactly what I was thinking of...


http://i817.photobucket.com/albums/zz100/Billb-pics/Eschdorf2010/100_0481.jpg

That ^ does not look very attainable for the club level rally team in the USA.

Below is a quote from one of the Safe Drives adverts on this forum. For club level geys with any seat, nets are your best bang for buck and easy install for club level team. Also, much less than new fancy head wing seats.

Hi All,

These rally specific Side Impact Nets offer a HUGE safety upgrade in a rally car no matter WHAT seat you have. Even seat with head surround can benefit from these nets.

We have used rally nets in our own rally car for over two years without problem.

The Driver restraint net is designed to help keep your head and your shoulders in line with your hips during a heavy side impact. You see, our FIA type race seats hold our hips in the seat really well but not our upper body. Also, seats have been shown in testing to fail above 50G impact.

The nets reinforce the seats while increasing safety a huge amount.


Quote:
Originally Posted by Teresa
Maybe it is a false sense of security, but I do feel much safer in the car after installing the four nets. My Sparco seat does not flex like it used to!! I feel like I am in a cocoon....


Best Regards,
Teresa
Co-Driver/Silly Seat Occupant


The minimum we recommend for a rally car is:

Safety Solutions Rally Driver Net (http://www.safedrives.com/proddetail.asp?prod=SafeSolRallyNet&cat=92)
http://www.safedrives.com/prodimages/lfttech/windownet/rally_lg.jpg (http://www.safedrives.com/proddetail.asp?prod=SafeSolRallyNet&cat=92)
Polyester Webbing = $125 (http://www.safedrives.com/proddetail.asp?prod=SafeSolRallyNet&cat=92)
Kevlar Webbing = $155 (http://www.safedrives.com/proddetail.asp?prod=SafeSolRallyNet&cat=92)

Kevlar webbing has the lesser amount of stretch. Less stretch in this situation = safer but higher cost. Poly net better than no net at all. ;)

Please note the included ratcheting mechanism. You want these nets to be "guitar string" tight, literally wrapping your seats.

Check out our rally car shown here, again we have used these in our car for over two years. I have won two consecutive G5 Rally America Regional Drivers Championships ('06 & '07) racing in this car with this set up. I tell you it is not a problem at all from a driver perspective.


http://www.safedrives.com/prodimages/lfttech/windownet/SD%20Driver.jpg


http://www.safedrives.com/prodimages/lfttech/windownet/Sdnet1.jpg


http://www.safedrives.com/prodimages/lfttech/windownet/SDnet2.jpg

Above pictured are my old seats. ^^^

Below are my new seats for 2009 season:
http://farm4.static.flickr.com/3494/3468706455_3680af95f5.jpg?v=0

http://farm4.static.flickr.com/3626/3469520220_7b1d06e0b6_m.jpg

http://farm4.static.flickr.com/3637/3469520150_a09ec5910a_m.jpg

http://farm4.static.flickr.com/3542/3469520190_9f76bdafc9_m.jpg



http://farm4.static.flickr.com/3481/3468706541_e3550ee69a.jpg?v=0
http://www.flickr.com/photos/37781622@N08/


If you do not want or cannot accommodate the ratcheting mechanism on the standard Rally Nets then we recommend the HD system.

Safety Solutions Heavy Duty Rally Driver Net (http://www.safedrives.com/proddetail.asp?prod=SafeSolHDNet&cat=92)
http://www.safedrives.com/prodimages/lfttech/windownet/hdrally_lg.jpg (http://www.safedrives.com/proddetail.asp?prod=SafeSolHDNet&cat=92)
$170 (http://www.safedrives.com/proddetail.asp?prod=SafeSolHDNet&cat=92)
Only available with Kevlar webbing, a bit more webbing material as well. This net would not be "guitar string" tight but installed as tight as possible without a ratchet. ;)

[Josh wimpey]

That ^ does not look very attainable for the club level rally team in the USA.

The materials to make the panes yourself are quite reasonable. The aluminum honeycomb can be had for about $75 per door (about $300 for a 4'x8' sheet). Adding a couple layers of carbon adds maybe $50 per door assuming you can layup the resin and cloth yourself. So, for about $250 total, you could do this yourself if you have the skills. I would assume roughly 2.5 to 3-times the price to pay someone else to make them for you.


Below is a quote from one of the Safe Drives adverts on this forum. For club level guys with any seat, nets are your best bang for buck and easy install for club level team. Also, much less than new fancy head wing seats.


Nets and head restraints address a different issue than impact panels. One is for containment or compartmentalization and the other is to attenuate force, reduce peak impact G's, and prevent intrusion.

Despite the look of fancy carbon parts, the costs don't look too bad compared to either seats, or nets. After all, 4 nets alone cost between $500 and $680.

[Safe Drives]

The materials to make the panes yourself are quite reasonable. The aluminum honeycomb can be had for about $75 per door (about $300 for a 4'x8' sheet). Adding a couple layers of carbon adds maybe $50 per door assuming you can layup the resin and cloth yourself. So, for about $250 total, you could do this yourself if you have the skills. I would assume roughly 2.5 to 3-times the price to pay someone else to make them for you.





Nets and head restraints address a different issue than impact panels. One is for containment or compartmentalization and the other is to attenuate force, reduce peak impact G's, and prevent intrusion.

Despite the look of fancy carbon parts, the costs don't look too bad compared to either seats, or nets. After all, 4 nets alone cost between $500 and $680.

All very good points Josh.

However nets do allow a huge upgrade in side impact safety and are "off the shelf" / very attainable.