Non-linear material

Discussion about building and installing Elmer
Sayan
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Re: Non-linear material

Post by Sayan »

Okkk...In that case how will I define density and damping constant? If I don't provide young's modulus 200.e9 that will automatically be calculated in first material 1 definition as per F90 code...but is it possible to define density and rayleigh constants also in the bilinear material property section?
kevinarden
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Re: Non-linear material

Post by kevinarden »

yes you can put all of the properties in the material 1 definition

Material 1

! UMAT test
Number of Material Constants = Integer 5
Number of State Variables = Integer 7
! List material constants as {}:
Material Constants(5) = Real 0.3 .002 4E8 .025 5.5E8
UMAT Subroutine = File "UMATbi_linear" "bi_linear"
Name = "bi_linear" ! This specifies the CMNAME argument of UMAT
Density = 7850
Youngs modulus = 200.0e9
Poisson ratio = 0.3
Rayleigh Damping=Logical True
Rayleigh Beta=Real .0001

End
kevinarden
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Re: Non-linear material

Post by kevinarden »

This solution is an example, I removed the Element=P:2, the UMATs were not programmed with P elements in mind. They will work with higher order elements in the mesh. I changed the beam to an end loaded cantilever.
loaddef.png
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disp.png
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kevinarden
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Re: Non-linear material

Post by kevinarden »

sif and mesh
ycase.sif
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beam.grd
(587 Bytes) Downloaded 165 times
Sayan
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Re: Non-linear material

Post by Sayan »

Woww..that result is really interesting...I will use those files as reference for my future work...
Sayan
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Re: Non-linear material

Post by Sayan »

I have noticed one thing that when I am using rayleigh constant for damping in material 1 of bi-linear section as you guided me in earlier post, it's actually not taking into account damping effect...I have plotted some time history curve to check this where I found no effect of damping..whether bi-linear UMAT code doesn't consider damping effect?
kevinarden
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Re: Non-linear material

Post by kevinarden »

Have not tested it with damping, but I will try.

I worked through damping in the linear case, but have not tried it in non-linear.
viewtopic.php?f=3&t=6657&p=20860&hilit=damping#p20860
Sayan
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Re: Non-linear material

Post by Sayan »

Ok....I tried with different example..it's not working with elasticsolver in UMAT bi_linear material section..If you get any result please let me know...just for information when I was using 6 material constants in material 1 and another material 1 I defined by mistake in which damping was there, don't know how, but it was considering damping that time..I didn't find any explanation for this..
kevinarden
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Re: Non-linear material

Post by kevinarden »

Because the simulation type is scanning there are no dynamic forces, the dynamic forces are required for damping to have effect. In the problem the force is on all the time so damping would not matter. The beam would have to be in vibration (free or forced). To get vibration it would have to be a simulation transient, and UMAT is not supported under transient at this time
Last edited by kevinarden on 15 Mar 2021, 15:59, edited 1 time in total.
Sayan
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Re: Non-linear material

Post by Sayan »

I tried with transient method but it was showing
ERROR:: ElasticSolver: UMAT version does not yet support transient simulation.
Is there any update in devel bench?
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