I need assistance identifying the required formulae to choose materials in building a span.(adsbygoogle = window.adsbygoogle || []).push({});

The actual application is a bed frame of all things - but it can only be end-supported (simple end support).

The entire bed will move up and down on rails (this is in a motor home - which is why weight is critical - I need it to be light enough to move up and down and low enough mass not to rip free from its housing in a crash). I mention this to answer the obvious "Why not center support" and "Why not steel / wood etc" questions which is exactly what I'd ask in the same position.

The current implementation of this design uses steel angle L (totally over-sized and very heavy). In the event of a crash I'm quite certain it will become a deadly projectile as it rips free from the rails. To boot, it is very difficult to push up into the locked position overhead. So I've decided to use aluminum - but am not sure how much I need.

The span is 80 inch and will require 2 parallel angle-L beams made of aluminum. Wooden decking will lay across the flats of the two L's (plywood which will be pop-riveted into the flats of the aluminum).

The aluminum I have access to is 6061-T6

Ultimate Tensile Strength, psi 45,000

Yield Strength, psi 40,000

Brinell Hardness 95

Rockwell Hardness B60

I can get some standard denominations of L angle

1x1x1/4

2x2x1/4

3x3x1/4

Can get other sizes but instead of solving for a specific set of sizes I'd like to test each on a spreadsheet when finished.

The static load is 500lbs maximum (My wife and I with a good amount of margin) - I am not sure what to use for a dynamic load (any thoughts?)

I have never done any real mechanical engineering so I'm not sure what equations I'm looking for. I guess I would be interested in seeing deflection but have no idea how to determine where failure should happen.

Simplest way to design it may be center loading (worst case?)

I'd like to build this with economy of both materials and weight but with sufficient margin that it doesn't collapse - contradictions in terms but I think you know what I mean :)

If possible, please direct me to the equations I need. My math is fairly good up to some calculus but I'm not familiar with the engineering symbols and constants - please let me know what each element in the equation is (or direct me to a good resource with the same).

I'm eager to learn and really appreciate the help!

Be well,

George

p.s. will post images / video of finished project! Current system is being disassembled soon after I write this!

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# Angle (L) beam formulas needed

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