Hi kevinarden,
sorry, did not understand what you have done, what the solver scanned for...
wrong displacement values using "ElasticSolver"?
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Re: wrong displacement values using "ElasticSolver"?
scanning in the case of elasticsolver is just a step solution where each step depends on the previous solution.
Re: wrong displacement values using "ElasticSolver"?
Hi kevinarden,
I did the scanning on the applied force as you did using:
StressSolver and ElasticSolver
Nonlinear System Max Iterations = 1 and 20
with and without Large Deflection = False
I also computed the Young's modulus from the displacement obtained from the simulations
The results are as follows: The effect of Large Deflection = False is only noticeable with ElasticSolver and it is negligible in this problem.
IMHO the problem is linear.
StressSolver does gives the correct result (displacement and Young's modulus are as I'd expect them to be),
ElasticSolver don't (displacement and Young's modulus are wrong)
Thanks again
I did the scanning on the applied force as you did using:
StressSolver and ElasticSolver
Nonlinear System Max Iterations = 1 and 20
with and without Large Deflection = False
I also computed the Young's modulus from the displacement obtained from the simulations
The results are as follows: The effect of Large Deflection = False is only noticeable with ElasticSolver and it is negligible in this problem.
IMHO the problem is linear.
StressSolver does gives the correct result (displacement and Young's modulus are as I'd expect them to be),
ElasticSolver don't (displacement and Young's modulus are wrong)
Thanks again
Re: wrong displacement values using "ElasticSolver"?
Here Young's modulus E = 5e+6 while the intensity of applied surface force (traction) s = 5e+5, so in an uniaxial test one might expect a linearized strain ~ s/E ~ 0.1. I therefore think that nonlinearity starts to play a role.
If I set for example E = 5e+11 so that the assumption of linearity is surely sensible, ElasticSolver converges quickly and the solution is close to the linearized solution
ComputeChange: NS (ITER=1) (NRM,RELC): ( 0.17869899E-07 2.0000000 ) :: elasticsolver
ComputeChange: NS (ITER=2) (NRM,RELC): ( 0.17864402E-07 0.30766693E-03 ) :: elasticsolver
ComputeChange: NS (ITER=3) (NRM,RELC): ( 0.17864402E-07 0.0000000 ) :: elasticsolver
ComputeChange: SS (ITER=1) (NRM,RELC): ( 0.17863102E-07 2.0000000 ) :: elasticsolver
ComputeChange: SS (ITER=1) (NRM,RELC): ( 0.17869899E-07 2.0000000 ) :: linear elasticity
Re: wrong displacement values using "ElasticSolver"?
I did a mistake in recommending the use of the keyword Large Deflection in this connection. ElasticSolver understands it only when material model is described as UMAT subroutine. Here it shouldn't be used.kevinarden wrote: ↑23 May 2024, 12:17 According to the manual
Large Deflection = False
only shows up in the shell solver, not ElasticSolver
Re: wrong displacement values using "ElasticSolver"?
Hi,
we are not talking about real material properties here. We are talking about the model material properties.
The material is defined as follows:
Code: Select all
Material 1
Youngs modulus = 5e6
Poisson ratio = 0.0
End
Are you saying that the ElasticSolver decides by its own that beyond a certain strain the material is no longer linear?
Moreover, beyond the yield strength, in typical materials the Young's modulus decreases, whereas according to the ElasticSolver solution the Young's modulus increases at higher strain!
Again, I’m really sorry, but I cannot understand why the ElasticSolver gives those results.
I'd really appreciate to understand what's going on so that I can use the ElasticSolver when needed and I thank you once more for your help.
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Re: wrong displacement values using "ElasticSolver"?
Mika is correct that the Large Deflection = False works in Elastic Solver when the UMAT subroutine is defined for the material.
Converges quickly to the desired answer regardless of number on non=linear iterations.
Converges quickly to the desired answer regardless of number on non=linear iterations.
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Re: wrong displacement values using "ElasticSolver"?
I thought perhaps it was due to rigid body modes, ElasticSolve and StressSolve so not much like rigid body modes in a static solution. So I added some constraints to take out rigid body motion without impacting the results. ElasticSolve converged much faster, but still arrived at 0.0044 answer.
I attempted to do a comparison to Abaqus, but Abaqus also does not like rigid motion in static problems. I could not get to a solution with Abaqus
I attempted to do a comparison to Abaqus, but Abaqus also does not like rigid motion in static problems. I could not get to a solution with Abaqus
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Re: wrong displacement values using "ElasticSolver"?
I thought they were two independent bodies connected by springs, but apparently they share nodes at the boundary? That is a different problem than I thought.
Re: wrong displacement values using "ElasticSolver"?
The two bodies have one face in common, so they behave as a single body.
On that face, which is placed on a symmetry plane, there is a boundary condition (Ref) to "keep" the bodies in place
On that face, which is placed on a symmetry plane, there is a boundary condition (Ref) to "keep" the bodies in place