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Old 02-28-2011, 12:20 AM
Overkill Overkill is offline
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Default How much does aluminum expand?

Using .063" 5052 in an application where a 5' x 10' sheet has a 3' x 3.5' door in it, with almost zero door gap. Having seen flat sheet aluminum expand in the sun, I'm wondering if it will expand, locking the door in place, so it won't open...

So, is there a formula, or rule of thumb as to how much it will grow?

The application is the side of a teardrop trailer, with no shape in it. The hinge's are Soss hinges, so very accurate and you can get away with almost no door gap. I've fit the door in there, while it's nice and cold, but if I end up in the desert, still would like to be able to get inside.

John
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Old 02-28-2011, 12:36 AM
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Joe Hartson Joe Hartson is offline
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Here is a link for the coefficient of linear thermal expansion.
http://www.engineeringtoolbox.com/li...ents-d_95.html

It doesn't have a specific for 5052 but it would be close for all aluminum alloys. It expands in all directions. You can only control expansion in one direction.
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Old 02-28-2011, 12:39 AM
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Default Door

John:

Is there no framework to the door to retain it's shape? The one I made for a friend had a 3/4" steel framework with the aluminum wrapped around it with the corners welded and then pop riveted to the edges. He put a thin piece of plywood inside with upholstery on it. That was several years ago and it still looks good and is water tight.
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Old 02-28-2011, 02:23 AM
Michael Michael is offline
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John, you only need to worry if you have dissimiller materials joined together. If it is all al. everything grows and shirnks the same amount .

Michael
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Old 02-28-2011, 09:14 AM
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aluminun expands 5/32 per foot from molten to solid state (that's 1.005 in to 1.00 in).... I doubt that it will expand enough from 60degrees to 120 degrees to lock your door in place.
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Old 02-28-2011, 09:51 AM
cameron cameron is offline
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Here in eastern Ontario a dark painted car body in direct sunlight can get too hot to keep your hand on it comfortably. That's somewhere in the region of 150 degrees Fahrenheit. I'm pretty sure it could get hotter than that in the desert.

From 60 degrees F to 150 degrees, your 3.5' wide door would become about 0.05" wider, if it was unrestricted by the inside reinforcement.

To calculate the expansion of aluminum, multiply the length in inches times the number of F degrees change in temperature times 13, and divide by 1 million. This gives you the expansion in inches.

Someone please correct me if I've made a mistake here.

Dave Cameron
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Old 02-28-2011, 09:53 AM
Overkill Overkill is offline
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Default Trailer

Our trailers use a steel framework with aluminum attached. A buddy fastened the aluminum to all the framework cross members. When in the sun, the aluminum will expand and you can see the bulge's between the cross members, gets cold, it contracts and no longer has a bulge. On later trailers, we only fastened the aluminum around the perimeter to prevent this issue.

My trailer has the same steel framework, but the door is an aluminum framework. The door skin fits over the alum door framework, but stands a bit proud of that to hide the door gap. The exterior aluminum is fastened to the framework with panel bonding adhesive, or by being formed around and welded to itself.

I do have dissimilar metals, and will be using a voltage sponge to help with electrolysis.

On my next trailer - should I build one, it will be done much more like an airplane, using the techniques used in the Tourette build in the 50's.

Thanks for the answers.

John
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