Plate Deflection Formula Question
Plate Deflection Formula Question
(OP)
Hello,
I'm a hobbiest, not an engineer, and I need some help. I want to calculate some plate deflection numbers on circular plates using excel. I know there are on-line calculators that will do it, but I want to keep it in excel. So, my copy of Machinery's Handbook gives the following 2 formulas.
Stress = 0.39 * W / t^2
deflection = 0.221 * W * R^2/ E * t^3
I had no problems setting up both formulas. I can look up Poisson's ratio (0.39), and the other values are either known from the material or computed.
But I have no idea where the 0.221 comes from!! Google found me a couple of examples of the formula, and the value used in place of 0.221 varies with the plate material. Could someone tell me how to find it? Look it up - where? Calculate it - what's needed?
Thanks,
Alex
I'm a hobbiest, not an engineer, and I need some help. I want to calculate some plate deflection numbers on circular plates using excel. I know there are on-line calculators that will do it, but I want to keep it in excel. So, my copy of Machinery's Handbook gives the following 2 formulas.
Stress = 0.39 * W / t^2
deflection = 0.221 * W * R^2/ E * t^3
I had no problems setting up both formulas. I can look up Poisson's ratio (0.39), and the other values are either known from the material or computed.
But I have no idea where the 0.221 comes from!! Google found me a couple of examples of the formula, and the value used in place of 0.221 varies with the plate material. Could someone tell me how to find it? Look it up - where? Calculate it - what's needed?
Thanks,
Alex





RE: Plate Deflection Formula Question
It's been a number of years since I did in depth DE solutions, but I seem to recall that the only plate with an exact DE solution is triangular (the bi-harmonic equation?), so any other shape will be an approximate solution, reduced to a relatively simple algebraic formula, such as what you are using.
RE: Plate Deflection Formula Question
But my question is, where can I find this value? The MH example I had above is for steel. I found another example for lexan and the value was 0.0284. It seems there should be a table or something with this value, that's what I'm looking for.
Alex
RE: Plate Deflection Formula Question
Alex
RE: Plate Deflection Formula Question
So it sounds like your curiosity helped both you and them. :)
RE: Plate Deflection Formula Question
Quando Omni Flunkus Moritati