Excel program for Plate Stress Analysis 2

[marisse]

Anybody of you guys have an idea how to apply/create a Stress Analysis using excel?

I would like to get the max deflection and max stress for a certain vertical glass panel having dimensions of W x H. A uniform pressure P is applied on to the panel.

The glass panel having the following constants:

E = 72 GPa
Poisson = 0.22


I need your help guys.

Thanks a lot!
Marisse

 

[daveboy]

You could set up the equations for flat plates in Excel.

Never done it for a glass panel but I have done it for various round plates in steel, bronze and cast iron.

Roarks or a good structual design book on flat plates should help.

This should give you stress at the edge and centre and also deformations.

Or is this too simplified?

 

[daveboy]

Sorry you will also need the thickness of the panel if you want to do this

 

[electricpete]

The fact that you ask it as an excel question rather than a question in the mechanical form leads me to believe you were thinking of a finite element problem.

With a fairly simple geometry such as this (rectangular plate with uniform pressure), I'm guessing there must be an analytical solution available as well.

Sorry I realize this is not much practical help without the equation. Just wanted to mention it. Might be worth a post on a mechanical forum.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[GregLocock]

set it up as a PDE. Use some sort of iteration to sort the deflections out.

It is analagous to solving 2D groundwater flow problems using nets, which is a manual technique.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[marisse]

Thanks daveboy,

although it's too simplified for a beginner like me. If you could possibly show me how you've done it in round plates that might help a lot.

I can do it on a 2 side supported plate (like a simple beam) but I am having difficulty doing it on a 4 side supported plate coz i really don't know how to do it or what equation should i use.

By the way, the thickness of the plate is t.

 

[Qshake]

Use Roarks to write the formula in excel.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[daveboy]

As Qshake says - "Use Roarks" the methods are fairly systematic and can be easily turned into spreadsheets.

Alternatively the machinery handbook or probably any good structural design book should help.

For round plates it generally requires working out a series of constants / coefficents then doing simple multiplication and division.

Rectangular plates are simplier as there are less coefficents.

 

[electricpete]

From Harris' Shock and Vib Handbook 2nd ed Table 7.6:
“Maximum deflection and bending moments in uniformly loaded plates under static conditions”

Max Displacement wmax = alpha * P * a^4 / (E*h^3)
where
P = pressure psi
E = Young’s Modulus psi
h = plate thickness inch
a = plate width
b = plate height (b>a)
posson’s ratio assumed 0.3
alpha = depends on ratio of plate dimensions b/a

Simply supported edges
b/a = 1 => alpha = 0.044
b/a = 1.2 => alpha = 0.062
b/a = 1.4 => alpha = 0.077
b/a = 1.6 => alpha = 0.091
b/a = 1.8 => alpha = 0.102
b/a = 2.0 => alpha = 0.111
b/a = 3.0 => alpha = 0.134
b/a = infinity => alpha = 0.142

Built-in edges
b/a = 1 => alpha = 0.014
b/a = 1.2 => alpha = 0.019
b/a = 1.4 => alpha = 0.023
b/a = 1.6 => alpha = 0.025
b/a = 1.8 => alpha = 0.027
b/a = 2.0 => alpha = 0.0.028


=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[electricpete]

I agree finite element would give more flexibility to analyse cases not given in the tables.

=====================================
Eng-tips forums: The best place on the web for engineering discussions.

 

[daveboy]

You will find a paper with an alternative method here

http://www.ce.berkeley.edu/~rlt/reports/clamp.pdf

I haven't tried this method.

You will also find a spreadsheet for a simply supported rectangualr plate here

http://pergatory.mit.edu/2.007/software_tools/spreadsheets.html

Not quite what you are looking for as you are more likley to be fully fixed on all edges.