Is 20mm Plywood Enough for a 90kg Load on a Top Bunk?

[cabellos]

Stress analysis of bed design...

I have a bed design and i need to do a stress analysis of the top bunk under a 90kg load. I will be designing it from 20mm thick plywood but i need to work out whether this is thick enough to support the load and also determine the width of the leg supports.

In the diagram (attached) the bed slides up on slide rails into a locking position and 4 legs are pulled down fitting into holes in the lower bunk.

View attachment Assembly1.pdf

Please can people offer me some hints on how to go about this problem? Thankyou,

Cabellos.

 

[awermedia]

u can do it with ansys workbench easily.please contact me
dundarheybet@gmail.com

 

[FredGarvin]

Actually, no you can't. Plywood, like any other form of wood is technically anisotropic. You need to be able to account for varying material properties in different directions. An analysis with wood, or any other composite, is not a trivial task, especially when it comes to getting complete material properties. In the case of all woods, you have the added bonus of trying to nail down moisture content as well. In the case of plywood you are very much dealing with a composite because you have many lamina stacked with adhesive boding between them. That means you can have varying properties not only in the wood, but between the wood and the adhesive layers as well.

I would suggest doing some research into the testing and certification of furniture, especially in the realm of children's furniture to see if there are any rules of thumb or design guidelines that can help you.

The width of the leg supports should be easy enough to work out from basic statics. The stresses are something all together different.