# Stress Analysis - For Enclosures



## Virides (Mar 1, 2011)

I have decided just out of interest to explore ways of strengthening the span between two walls without using supports. This is especially a problem where glass tends to make the bottom of an enclosure droop from the weight.

Still a work in progress, but already i have found a way to reduce the stress however the displacement is fractionally more with chines than without. I am amiming to find a way to have no mid supports.

This is 19mm Wood with 100kg (980 Newtons) of force applied assuming the left, right and rear edges are affixed to an unmoveable fixture (ie. walls).






Red indicates intense stress although this is not outside the yeild strength of the material. Blue is good and green is well within limits. Though the one with chines has a higher peak stress point, it is more localised and not as spread out as shown in the first image.

Will update more as I progress on this and will let you all know what should be done to improve your enclosures 

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Well after extensive testing I can't seem to find a way to strengthen the panel (without using supports). I know some will say "why bother" but atleast now we know it is close to impossible to fix without some kind of internal support (other than using overkill material thickness). The only thing that showed promise was a way of adding lateral opposing compression to the top layer of the panel to act as a "spring" against the downward pressure of the load. But I couldn't figure out anything that would be "easy to achieve" without some specialised equipment.

If anyone else wants to test something out, let me know


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## Just_Plain_Nuts (Mar 14, 2011)

Is this to alleviate droop on the front of the enclosure which stops the sliding glass from moving freely?


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## bowdnboy (Mar 15, 2011)

Sorry, but am i missing something??

Why not just run timber / melamine(whatever your making the encl out of) horizontally along the top and bottom from wall to wall afixed. It only has to be an inch thick (if that), and that solves this problem. 

Noth sure if thats the sort of thing your talking about???


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## Virides (Mar 15, 2011)

Just_Plain_Nuts said:


> Is this to alleviate droop on the front of the enclosure which stops the sliding glass from moving freely?


 
Yes





bowdnboy said:


> Sorry, but am i missing something??
> 
> Why not just run timber / melamine(whatever your making the encl out of) horizontally along the top and bottom from wall to wall afixed. It only has to be an inch thick (if that), and that solves this problem.
> 
> Noth sure if thats the sort of thing your talking about???


 
I understand this, however was just curious to see if there was a way without requiring any additional supports. Also I wasn't setting out to say that everyone is wrong how they do it, I was merely investigating it and thought I should show what I had found.

It obviously can't work within the means of most people. Was just curious


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## James_Scott (Mar 15, 2011)

It's possible to do although just not cost effective. Think of a runner in a surf board. If you cut the panels into smaller pieces and them glue them back together with steel runners in between then this would fix the bowing. You would lose a lot of the appeal to the overall look not to mention heat transfer issues through the metal. It's an interesting theoretical problem though. Not every posting has to practical. I say keep working on it and post you findings.


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## Virides (Mar 15, 2011)

I do have a theory to test - 2-3 sheets of Low profile corrugated iron sandwiched between two 12mm ply sheets then filled with expanda-foam. Kind of like a large composite panel. The corrugation acts as the internal support and the ply contains it all. The foam stops the free movement of the panels and helps dampen the effects.

I will be looking into making this panel and letting you know how it goes.


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## Just_Plain_Nuts (Mar 15, 2011)

It would be easier to use fibreglass with a foam spacing. Very stiff and strong and light


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## cris (Mar 15, 2011)

Im not exactly sure on the application of what you are doing. You could put the floor on an incline to reduce bending without using extra material, but i dont think that is going to be practical.


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## Virides (Mar 15, 2011)

Just_Plain_Nuts said:


> It would be easier to use fibreglass with a foam spacing. Very stiff and strong and light


 
That would work although I am curious to see if there is a way where the average person (who may not know how to fibreglass) could achieve it.



cris said:


> Im not exactly sure on the application of what you are doing. You could put the floor on an incline to reduce bending without using extra material, but i dont think that is going to be practical.



This is where you may have two enclosures ontop of eachother and the roof of the lower one is the floor of the upper one. The weight from the top enclosure is affecting the sliding glass/doors on the lower one.


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## bkevo (Mar 15, 2011)

i may be missing something but to stop an enclosure floor from bowing a steel angle can be fitted to the cage floor ( L shaped angle screwed across the lenth of the cage floor, with a few fixings along the length of the angel, it simply act as a beam/lintel)
2 sides and rear of an enclosure floor can simply be screwed through the side and rear upright panel/s.


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## Virides (Mar 16, 2011)

Initially I was looking at a way of doing it without supports (such as the steel angle) and while I was able to reduce the stress, I was unable to reduce (significantly) the displacement. Ofcourse the steel would stop/reduce this, but it wasn't my goal.

I guess this is a problem for some people who don't want to go to the extents of fibreglass/steel as it is out of their reach, so I was after something that most people could achieve - but it is proving difficult 

Not after a magic answer here, just exploring options and thanks for the input thus far , appreciated.


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## sambino (Mar 16, 2011)

i have done this with my enclosures using a lintel system which i glue my tracks to never had a problem even with 4 stacked up still kind of different to what you are talking about


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## drinkies (Apr 6, 2011)

with a plywood base you could "pre-stress".cabinetmakers will steam plywood and put it in a press overnight to cool and retain shape.a premade bow in the wood that would flatten out under pressure ie the tanks above.
could be possible to do at home with supporting bricks under plywood,steam mop and correct weights.


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