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 Sep 24 comment FEM Solution desired for “Plate with orifice” deflection: Application of Boundary Conditions and use of Regions Thank you! I never tried DSolve for this problem. Sep 23 comment Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) @bbgodfrey I am not sure. However, I am curious to know what the deflection (w) is at "long times". If for a negative time derivative, it is around the same value as the question this refers to, I would say, YES, the time derivative should be reversed. I hope that make sense? Thank you for pointing out that possible source of error. Sep 23 comment Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) @bbgodfrey They do exist for rectangular plates with rectangular and circular holes 1. Empirical solutions for circular plate with hole for deflections are readily available though. I did find a book entry by Timoshenko on elastic stability of circular plates with and without a hole 2. I do not have access to this paper. Sep 22 comment Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) @bbgodfrey 0.33 is a good standard value for nu. Sep 22 comment Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) @bbgodfrey yes it is supposed to be nu which is defined. It is poissons ratio . (can't type efficiently on phone right now...) Sep 22 asked Using BSpline as initial condition in NDSolve Sep 21 comment Nonlinear differential equation: numerical solution I have generally found that for equations with singularities due to a 1/x type term, Method->"LSODA" has usually worked wonders. LSODA has generally been more time efficient than ExplicitRungeKutta and efficient in resolving stiffness. Sep 20 awarded Popular Question Sep 19 comment ODE w/seasonal forcing term Can you share what book you are using? Sep 19 comment Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) @xzczd It does return an interpolating function. However, this interpolating function gives a plot that shows a deflection and deflection "shape" that doesn't approach what was calculated here. I have made an edit to the question to reflect your comment. Sep 19 revised Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) added 1505 characters in body Sep 19 comment Solving a nonlinear PDE with Mathematica10 FEM Solver Is FEM a must? I have had a lot of success with non linear PDEs with NDSolve. Yes, you will have to deal with stiffness but the Method->LSODA is quite the "golden hammer" for stiff non linear problems. Sep 19 comment Nonlinear FEM Solver for Navier-Stokes equations in 2D What fluid dynamics problem are you trying to solve? Lid driven flow? This information will be useful. Sep 18 revised Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) edited title Sep 18 awarded Promoter Sep 14 revised Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) added 30 characters in body Sep 14 asked Time evolution/dynamics of circular plate with hole (Biharmonic equation and stiffness) Sep 10 accepted Mathematica not responding to clean start-up Sep 10 comment Mathematica not responding to clean start-up @ilian I know that this has been answered elsewhere but can you post our chat transcript (which was a definitive solution) as an answer? I assume that is allowed (since this is the internet?) Sep 10 comment Mathematica not responding to clean start-up @Gansukh if you read the chat transcript between me and ilian (from a few comments above), you will find a solution described in there.