material thickness calculation

[jleep]

Looking for direction. I haven't had to do this in a long time.

I would like to calculate the thickness required to support 1000lbs on a piece of glass 8" wide. Support will be on either end (.25" on either end of the glass). The glass will be 8' long. No specific glass has been selected at this time. Will start with silica glass but more than likely move to a cermaic type glass (Robax).

Point me in the correct direction.

Thanks.
jl

 

[14159]

First thing you have to do is establish an allowable or working stress for the glass. I think you'll have to pin down a manufacturer and then contact them. I'll be interested to know if anybody else refers to a standard table of glass working stresses because I've never seen one.

After that, it's just basic mechanics to calculate the applied stress. If it's like a 2D beam or slab, then simple wL^/8 or PL/4 will get you a moment that allows stress calculations. If it's a plate bending problem, then you can either make conservative assumptions, find your friendly plate bending tables to get moments per unit width, or you can use a simple shell or plate bending FE calculation.

14159