Camper Structure advice.

[Mhambi]

Good Morning all,

Any structural engineers out there? Im looking for some advice on the strength / safety of building a Frame for my camper.
First of all the size of the Rectangle camper is 5m Length x 2.5M Width x 2.2M height.
This will be mounted on a torsion free flatbed.
The walls will be 55mm GRP, Made up of 2mm Fibreglass, 4mm ply, 44mm foam, 4mm ply, 1mm fibreglass. There will also be a couple of vertical strengthening wood beams in the foam for added strength.

Now comes the tricky part, I want to use 100mm x 100mm x 6mm Aluminium angle to build the frame in which the panels will be glued to.

The question, Will this be strong enough or would I need to reinforce somehow?

Any advice will be greatly appreciated.

 

[tonyidle]

I'm no structural engineer or expert in this area but you won't find a frame of any sort in a commercially-built A class. There is the base vehicle bulkhead and usually a steel hoop behind the cab area for seat belt attachment. Otherwise it's a box made more rigid by internal structures, furniture, and partitions.

 

[Wagoneer]

This website might help but some of the info is a bit dated http://www.silkroute.org.uk/equipment/index.html

I've rubbed shoulders with many structural engineers during my career as a Civil Engineer but few, if any, would be able to help in assessing the dynamic loads experienced in off-road vehicles. However, as you are mounting on a torsion free flatbed, I guess the normal construction techniques as used in A class motorhomes would be a starting point with enhanced torsional rigidity for extreme operating conditions.

As previously mentioned, an internal layout with internal lateral partitions could be advantageous to torsional rigidity.

 

[Riverbankannie]

Check the thread by MANGOFORTH . He seems to know what he is doing and a few of the other contributors to the thread .

The Big Lorry to Camper Conversion

So, long story short. Wanted a motorhome, ended up with a lorry. The body was rotten, kept it anyway. A quick camper conversion has spiraled out of control massively..... I've started the work already but I'll drip feed the photos over the next forever. Feel free to help and Enjoy. In the...

www.motorhomefun.co.uk

 

[funflair]

I would be tempted to drop the ply and wooden components in the wall and rely on bonding the GRP skins to a PU or styrofoam core, there is no frame in our A class box.

Martin

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[Mhambi]

Thanks for the link Wagoneer, Ive read that article. Its got some very interesting points. What Ive decided on doing as well in addition is once Ive glued the panels in place I will build in a second frame on the inside, This way it should be nearly indestructible.

 

[MANGOFORTH]

Are the panels full size? Aluminium extrusions will be absolutely strong enough for what your doing. And judging by your photo you aren't short of a penny so thats the route I'd take. Hard to properly assess without a picture of the plan.

 

[Mhambi]

Hi Martin, I was told to add the ply and beams to enhance the strength of the panel. I have a 6 Ton payload so not overly worried with the additional weight. Im also going to be hanging some high level cupboards on the walls which the 4mm ply would help to secure.

 

[Mhambi]

Ive eventually completed the frame. The frame is fully mounted in the 3rd Pic.

 

[Mhambi]

And the panels have arrived, 62mm 5 element GRP Panels. Now to get some decent weather so I can bond them in. Advice says it should be no less than +10 deg......... Im not seeing anything above 8/9 for the foreseeable future........

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[MANGOFORTH]

Proper job! Keep the photos coming ???

 

[Mhambi]

Quick question, Im going to Bond with Sikaflex 252, Should I use Sika 206 or 210 primer?

 

[Mhambi]

Managed to fit the roof panel over the weekend, These panels are seriously strong but very heavy too. In hind sight I think 50mm 3 element GRP would have been more than sufficient.

 

[MANGOFORTH]

What is the make up of the panels?

Just re read the first post, but you went for thicker panels, so the same makeup just more insulation?

 

[tacr2man]

I shouldn't worry about structural strength , as you have overdone it in reality .
My hab box is built for HD mil use , and isn't on a 3 point mount , being direct bolted to chassis ( although a special non torsion design) . The walls etc are 40mm ali ply foam ply ali composite (very light) . The frame is only 2.5mm ali 100X100 angle with steel top end caps for lifting whole loaded unit off . It is blind riveted all over with monobolts in high stress areas.
Sika primer is a very good move 210 seems most relevant , probably test on piece of composite , its ok for ali . 252 is also what i would use. Thickness of sika is also a factor when getting max strength of joint .

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[Mhambi]

What is the make up of the panels?

Just re read the first post, but you went for thicker panels, so the same makeup just more insulation?

They are a little different, 2mm Fibreglass / 4mm Ply / PU Foam Core / 4mm Ply / 2mm Fibreglass.

 

[Mhambi]

Managed to fit the floor and one side panel this weekend, Its starting to take shape.