mixed methods
mixed methods
(OP)
Hello everyone, I have one problem:
I'm trying to make a FEM algorithm for Euler-Bernoulli cantilever beam based on Hellinger-Reissner principle with Hermite interpolation. Even though I obtain a very good convergence for displacements and quite good for rotations, the convergence for bending moments and shear forces is tragic! Is enyone who can tell me what is the reason for this behaviour?
Thank you in advance and sorry for my english :)
I'm trying to make a FEM algorithm for Euler-Bernoulli cantilever beam based on Hellinger-Reissner principle with Hermite interpolation. Even though I obtain a very good convergence for displacements and quite good for rotations, the convergence for bending moments and shear forces is tragic! Is enyone who can tell me what is the reason for this behaviour?
Thank you in advance and sorry for my english :)





RE: mixed methods
RE: mixed methods
RE: mixed methods
Also why are you using a mixed method for a thin beam formulation..you might as well add in shear stiffness and make the beam a Mindlin type if you are going to use a mixed method.
RE: mixed methods
RE: mixed methods
RE: mixed methods
RE: mixed methods
corus
RE: mixed methods
RE: mixed methods
RE: mixed methods
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, but I discretize Hellinger-Reissner functional by myself so I can't be sure that it is good. Why can't I use cubic functions to approximate the Moment and Shear? Should I try linear functions for the Moment and Shear and cubic for the deflection and slope? What do you think about convergence that I have just mentioned above?
RE: mixed methods
Just a few second ago I have tried my algorithm without uniform load q (only with concentrated force). The solution was exact for all quantities, even for M and Q!!! I think this is because of strong formulated constitutive eqations. If w and fi are exact so M and q are. On the other hand if q is constant and differs from 0 the solution for w and fi are exact only at nodes and and functional "want" to map M and Q from bad daflections and slopes. Maybe this is the reason of this slow convergence? Maybe it is also bad idea to use mixed method to thin beam problem :).
with kindest regards
Krzychu
RE: mixed methods
RE: mixed methods