Finite Element Analysis Question

[Dlmyln]

Hello all,

I am modeling in SAP2000 a monolithic panel of Plexiglass of 1-1/4". I have entered all the material properties, loads, geometry and obtained the reactions and stresses of the shell.

If I see the shell stresses of the panel, how do I know if the Plexiglass can withstand it? Let's say I obtain a maximum stress of 500psi. Do I compare this value with the tensile strength?

Need some guidance in this part, thanks!

 

[canwesteng]

Maximum principal or maximum von mises stress? I'm guessing plexiglass is ductile so you should be looking at von mises. You would compare that to tensile capacity, but if it's a sustained load you need to consider creep effects as well.

 

[goeasyon]

You can compare the maximum stress with the yield stress material and some safety factors.

https://welsim.com

 

[WARose]

It depends on the stress type. You don't compare the allowable tensile stress to the calculated shear.

And as far as combined stresses go......I know nothing about plexiglass.....but for a ductile material, you combine stresses as per the von Mises criterion, for a brittle material failure, the Mohr–Coulomb failure theory is often used.

Of course, the failure criteria may be dictated by relevant codes. (Not sure what governs Plexiglass.)