Composite flooring for auto/transport use?

General Composites Discussions Composites Talk
#1

I have been trying to figure out what kind of material would be best to use as flooring in a van that I’m fitting out. It needs to be waterproof and reasonably durable - so that puts out the option that 99% of people would go for - plywood.

I finally found a German company that manufactures a product specifically designed for automotive flooring: http://www.seconect.de/
But unfortunately it seems like there is no retailer in Australia.

The idea has crossed my mind that I could just make my own…

I wondered if anyone here is familiar with the product?

From what I can tell, it’s based on another product that they make called VarioLine which is a foam core sandwiched with plastic sheets. To make the Seconect it seems like they add some additional layers to that product, maybe fibreglass?

I’m thinking that I could make two sheets to form the outer skins, then use some plastic standoffs (not solid, but a frame type so the foam could fill around them) to hold the two sheets apart at the correct distance. Then drilling holes into the top sheet to inject polyurethane foam. (I would flip this and use the drilled side as the bottom surface when in use.)

It would be installed over a bare metal floor in the van which has the usual type of corrugations/ribbing. They are probably not more than 50mm apart, so I don’t think I would even worry about filling the concave areas, although this could easily be done with rubber inserts to reduce the maximum possible deflection. I won’t be loading pallets etc., maximum load would be a motorcycle, say 220kg max.

As far as layup I think I would aim for 15mm total sheet thickness. For the outer layers I would guess that a biaxial (±45º) and unidirectional/uniaxial would be all that’s needed, maybe 6-700gsm total per layer (or just a layer or 600gsm quadriaxial)? The compressive strength would be the most important thing. Resin choice - I would be inclined to use a lower-spec epoxy resin which has more flexibility. The idea being that a more flexible resin is less likely to crack if something is dropped on it?

I would aim to make it as a single piece, about 4,200 x 1,780mm. Probably add some kind of anti-slip grit to the top side.

I just wanted to know what people think of this idea? Any comments and suggestions are welcomed!

#2

I always thought of doing something similar for my van and pimping out the back of it but its one of those things I havent got around to yet.
If you’re just making a flat panel, surely it would be handier to just get an 2m x 1m or whatever sheet of foam as opposed to making the skins, drilling and then filling? You can get sheets of polyurethane if thats what you’re after and they’re quite cheap.
Also, if its anything like my van that doesnt even get heavy abuse, there’ll be some hard wearing materials required on the uper surface, so maybe a layer of aramid somewhere in there or even basalt if you’re that way inclined. May as well make it look good when you’re going to that bother :slight_smile:

#3

:stuck_out_tongue:

Well this is why I love this forum. Great idea! Now why didn’t I think of that… I think this whole thing has caused me to lose my brain. Haha. (It’s actually part of a fitout for a work vehicle, was planning to be ready for work by September, but that ain’t gonna happen… let the stress begin…)

The other thing I just thought of was using a plastic/polypropylene honeycomb core instead? I was searching a bit more and found a reasonably local company that manufacturers panels using polypropylene honeycomb (preglassed), up to 11m lengths! They sell the honeycomb as well.
http://www.polycore-australia.com.au/
I’ll contact them tomorrow and see what I can find.

Then again, if polyurethane foam sheet is going to be okay, it will win out based on cost.

Interesting that you mentioned basalt - I never really considered that before. That’s another one I’ll have to try and find a local supplier for. Just so I understand this correctly - this would be used to add abrasion resistance to a surface layer (in this application)? Can you use basalt as a surface layer or does it need to be within a laminate?

Although the surface finish isn’t too important to me… I wouldn’t be making perfectly smooth glossy sheets anyway. I’d probably just join together some corflute sheets as the “mould”. And would add a topcoat/flowcoat with an anti-slip additive when it’s all done.

#4

Ha ha, sounds like one of those things you’ve been looking at for a while so is hard to see anything than whats in front of you. Im guilty of that everyday thats for sure!

I havent used basalt in anything other than small samples and of course it isnt really needed or anything - something like diolen or kevlar would do the job but basalt is pretty cool. I mean, its a rock so rocks are normally hard enough wearing :slight_smile: but it just adds that different cool factor as much as anything.
http://www.basaltex.com/ sell it in europe from €5-10 per metre squared approximately if you’re interested. Not sure about Oz suppliers though.

You could get a sheet of thin alu or something like that and glue it to a 2 x 1m sheet of plywood or something to give you a large cheap and relatively smooth tool. Ive used a big sheet of toughened glass in the past too which can work.

Just one other thing, you’re doing this mainly for the fun and for aesthetics arent you? Why not just create some thin laminates without a core and bond them to a plywood backing for example? This would be easy, cheap and probably more durable than using a low density core. For example, if your bike falls over, it could take a good number of plies so stop a pointy foot-rest or something puncturing it. You dont need a super stiff structure here or anything so I would ditch the core and just put facing skins onto timber or something. Or again, if you want something stiffer, just use the plywood as a core: again a cheap, simple and durable option

#5

Cheers for the tip on ply + ally sheet for tooling. Trying to keep the cost down though, otherwise I might as well just go for ally checkplate…

It’s not for the fun & aesthetics so much - I really do need waterproof flooring that is reasonably durable and flat (although I will enjoy building it every step of the way). If the metal floor in vans were not corrugated or ribbed, it would be a lot easier… I also wanted a waterproof core that wouldn’t be damaged if the skin is broken. At least if it’s polyurethane or honeycomb there won’t be any permanent damage and I can just patch it up & repair it.

Good point about a footpeg going into it… I will definitely add some Innegra!

I have found a supplier who can do sheets of polyethylene honeycomb, glassed for $88/m. That was for 25mm total thickness, 1mm glass each side. That’s what they came back with after I said I would be using it for a floor covering/surface… any ideas if that kind of thickness is really necessary? Trying to save as much headroom as possible.

Edit >>

I meant to add that I found that the optional factory wooden (plywood) floor offered by Mercedes in their Sprinter vans is only 5/16" (~8mm) thick. I was surprised to see that they offered anything that thin… their Body Builder Information Book recommends 12mm ply as a floor covering. It just makes me think that strength isn’t that much of a concern, even though the floor is ribbed. When I saw that they offer 8mm ply as an OEM option it just gave me another reason why I may as well just go with PU foam core?

The other question is that I’m not sure if a polyurethane foam would be strong enough? Is it better to use the polypropylene honeycomb? Compression strength would be the main thing here, I’d have thought? Looking up some info on structural polyurethane composite panels, they all seem to use fibreglass reinforcement through the PU foam core. Makes me wonder if it’s better to split the core into 2 or 3 layers of foam with a layer of glass between? It would add some weight, but would have to increase the strength a lot as well?

#6

What about truck bed liner?

#7

herman - do you mean the spray on type? Or just a rubber liner?

I’m actually going to be spraying Raptor liner as soon as I have the van prepped hopefully this week. The old (poorly installed) plywood floor had worn through the paint and there’s some surface rust to fix up. The Raptor should just help minimise any problems in the future. The way I see it is that it’s just an extra heavy duty 2k paint, a bit of insurance against future damage & wear. One thing I definitely don’t want to have to do is repaint anything for a long time… I am okay with building a new replacement floor if the first one only lasts a year, or gets damaged etc. But no more painting! (Very different if I was just painting a new part like a plug though.)

But then I still need a flat surface on the floor. Even if there was a properly fitted rubber liner available (that would fill the corrugations and give a flat surface) it would not be cheap. So believe it or not - going the composites route is actually looking quite promising from the cost & functionality side of things!

The most tricky bit will be that it’s going to be a large piece… total size will be about 4,300 x 1,800mm.

#8

I meant the spray type.

Another thing that jumped my mind: Flexible PU rubber. You can cast it in the truck bed (make sure the truck stands level). Can be a quick fix.

#9

Hey… now there is an idea…! :smiley:

Do you have any specific products in mind? I don’t know anything about those casting/liquid type products.

I’m guessing something with a harder surface would be what I want… something with a Shore A rating around 70-80? What other properties would be desirable? Or are most of those harder PU rubbers fairly durable?

Looking at some different products from Smooth-On and Dalchem it seems like most have a pot life of only 5 minutes?? :eek:
Although I suppose all I would have to do is just pour it out until the level is right.

Edit >>
Just looking into PU rubbers a little bit more and found that all PU and silicone rubbers will absorb oil? The van will be used as basically a mobile workshop type setup, not that there will be fuel and oil being thrown all over the place, but a spill is bound to happen… Do you think a PU rubber would still be suitable? Maybe if I just seal it with epoxy resin or something like that? Then I could use an anti-slip additive on the surface (not such a bad idea), but the underside would need to be sealed as well in case any oils got under it.

Edit #2
Just trying to price up a PU rubber, thought I would try and estimate the volume of product needed. By my calculations it’s quite a lot… 4.3m x 1.8m x 0.03m (let’s say 3cm thick, although it would be even more than this because it has to fill the corrugations, and go above the higher convex corrugations as well) gives 0.2322m³. Converting to litres gives 232.20L! :eek:
Either I’ve stayed up too late again and my brain signed off hours ago… or I’m back to the idea of a sandwich constructed floor.

#10

I cannot recommend you any products, you are half-way around the globe! :slight_smile:

I do recommend contacting some off-shore repair facilities. These use PU rubber. As for oil resistance: I would need to ask my colleague. He is the PU expert.

#11

Haha, no problem. Another question about the PU rubber - do you think it could be made in an even thickness sheet, say 13mm, or would much of the durability and strength depend on the large surface area of being in contact with the entire corrugated floor?

In either case I think it’s not really an ideal option as far as cost goes… it would take 100 litres just to make a 13mm sheet to cover the area I need. Very pricey… (Although I’m still interested in the above question for my own knowledge.)

Well I priced up the fibreglass sandwich option, rough guess on the core price since Corecell M80 3mm is the only one I had a price for (only one I’ve used before). The price on the Corecell is $24/m², generic PU foam would be cheaper for thicker but that price is okay for estimates. Not sure if I am overbuilding this, but here’s what I was thinking (all woven glass):

295gsm glass (top layer)
Innegra
295gsm glass
195gsm glass
Core
295gsm glass
Innegra
295gsm glass

That prices out to $115/m² (using epoxy resin).

I went back to consider the option of an aluminium checkplate floor and it seems like that might actually be the more cost effective option at ~$40/m² for 3mm plate.

So the question now is - am I going overboard with what I’m proposing for the composite panel? I don’t think there is any way it could come close to the cost the ally checkplate. Time is getting away from me and there is a definite plus side to being able to get some ally sheet and install it right away. Shame… I was getting excited about making something!

#12

Sounds like you’ve just got to the over-thinking stage doesnt it. One of my particular problems is over-thinking things and then actually getting nothing done. Ignorance is bliss occasionally and results in products being finished as opposed to mental concepts only: so what materials can you get a hold of easily and cheaply? Go with that first and wrorry maybe about an improved Mk2 at a laterdate.
Maybe even low cost expanding PU to take up the corrugations at the bottom then the glass laminate up top

#13

Yep - it’s all new territory for me… but I’ve decided to just go ahead and build a much thinner panel than originally planned. I remembered that I had a bunch of test pieces here using carbon/fibreglass and the Corecell 3mm - I put one of them down across the groove in the floor and gave it the old “bodyweight test” and surprisingly it didn’t flex very much at all… so I’m just going to go with something like that.

The layup on that piece went like this:

195gsm carbon fibre
68g Innegra
165gsm e-glass
Corecell 3mm
195gsm carbon fibre

I won’t use CF (to save cost), but I’ll go with that kind of layup, something much thinner for Mk1. Perhaps not the Corecell either… I found a supplier that can produce 4m long sheets of PU foam, just not sure on the difference between the Corecell and structural PU foam? The PU is available in minimum thickness of 12mm, looks like I will be doing another test piece…

Also if I can’t get a single piece of foam, I wonder if it would make any difference if I use multiple-piece core?

#14

Why not just use laminated herex foam? or even laminated plywood?

#15

Hey fiberpro, I must have missed your post…

What is herex foam? Just a type of structural core material?

I did consider using ply composite panels (foam core with A-grade ply bonded to each side), the local composites supplier had them at a pretty good price, but I thought it would all end badly if the ply was punctured and it got wet.

So I went ahead and used a 12mm structural foam core, a couple of layers of biaxial glass on each side. It’s nearly finished now - pretty happy with how it’s turning out. Biggest composite job I have attempted yet! Just putting some finishing touches on this afternoon and then it should be done… I’ll post up some photos and details in the showcase forum probably over the weekend.

Edit >> Okay, a bit longer than that weekend I mentioned, but the thread with all the details is up here now:
http://www.compositescentral.com/showthread.php?t=8828

#16

Hi all,

Well it’s been 5 years that I’ve been using this floor panel - it’s done extremely well, very glad that I chose composites over other materials as I have had zero worries about it getting wet and it’s been surprisingly durable, especially considering that I never planned to load & transport ~400kg machinery!

But now that weight has taken its toll… I basically have a ride on mower parked in the back of the van 85% of the year I’d say. The majority of the weight is on the drive wheels in the middle of the machine, and when the temperature rises inside the van it has been enough to allow the floor panel to deform in those sections. (I only used polyester resin and it doesn’t have high enough Tg to stand up against that weight and the constant high temps.) Enough deformation so that the underside of the panel has been rubbing on the ramp as I pull it out… pretty sure it’s through to the foam core…

I’m not sure how to go about fixing/reinforcing the panel - what do you all think?

A few ideas have been floating through my head - remove what’s left of the foam core in that section and laminate in a piece of 12mm ply? Or just use a section of structural core material? The area I’d have to replace is probably 1,200 x 500mm.

I’ve attached a photo to show the setup, apologies for my clumsy fingers - I was trying to shield the phone from the sun glare. But you can see how I’ve used the panel in a false floor to all easy storage of the ramp (made by a local engineering shop, based on my measurements using 3 lengths of aluminium plank).

Cheers!