StressSolver non-linear material
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- Location: Peterborough, England
StressSolver non-linear material
Hi Elmer team
Is it now possible to define a non-linear material for use in the stresssolver model?
I have tried doing a tensile test simulation using the following material properties
Material 1 !! non-linear stress-strain material property
Name = "PBT plastic"
Poisson Ratio = 0.37
Youngs Modulus = Variable Strain ! @ room temp : secant modulus data
Real
0.0000 4560e6
0.0033 4560e6
0.0066 4490e6
0.0099 4360e6
0.0132 4190e6
0.0165 3960e6
0.0198 3700e6
0.0231 3410e6
0.0264 3110e6
0.0297 2820e6
0.0330 2560e6
End
Density = 1370
End
But to no effect the resulting stress strain output is linear with a constant Young's modulus.
Regards
Mark
Is it now possible to define a non-linear material for use in the stresssolver model?
I have tried doing a tensile test simulation using the following material properties
Material 1 !! non-linear stress-strain material property
Name = "PBT plastic"
Poisson Ratio = 0.37
Youngs Modulus = Variable Strain ! @ room temp : secant modulus data
Real
0.0000 4560e6
0.0033 4560e6
0.0066 4490e6
0.0099 4360e6
0.0132 4190e6
0.0165 3960e6
0.0198 3700e6
0.0231 3410e6
0.0264 3110e6
0.0297 2820e6
0.0330 2560e6
End
Density = 1370
End
But to no effect the resulting stress strain output is linear with a constant Young's modulus.
Regards
Mark
Re: StressSolver non-linear material
Hi Mark,
Someone knowing about it may reply to your query on Table method.
Can you once try defining the User Defined Function for E=f(strain), and see the result?
viewtopic.php?f=3&t=3855
Yours
Anil Kunwar
Someone knowing about it may reply to your query on Table method.
Can you once try defining the User Defined Function for E=f(strain), and see the result?
viewtopic.php?f=3&t=3855
Yours
Anil Kunwar
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Re: StressSolver non-linear material
Hi,
one could check in the code if a variable Young's modulus is possible at all. I can't due to lack of time...
HTH,
Matthias
one could check in the code if a variable Young's modulus is possible at all. I can't due to lack of time...
HTH,
Matthias
Re: StressSolver non-linear material
Hi Matthias,
You are right that StressSolver in the source code does not have a variable Young's Modulus.
I compared HeatSolve and StatCurrentSolve with StressSolve and found out the following differences in the code of material properties:
1. Heat Conductivity in HeatSolve as a Function of Temperature (Can be defined via the ListGetRealArray subroutine. Also is defined ALLOCATABLE)
2.Electric Conductivity in StatCurrentSolve as a Function of Temperature (Can be defined via the ListGetRealArray subroutine,Also is defined ALLOCATABLE)
3. Youngs Modulus is defined as following in the StressSolver
Yours
Anil Kunwar
You are right that StressSolver in the source code does not have a variable Young's Modulus.
I compared HeatSolve and StatCurrentSolve with StressSolve and found out the following differences in the code of material properties:
1. Heat Conductivity in HeatSolve as a Function of Temperature (Can be defined via the ListGetRealArray subroutine. Also is defined ALLOCATABLE)
Code: Select all
REAL(KIND=dp), ALLOCATABLE :: MASS(:,:), &
STIFF(:,:), LOAD(:), HeatConductivity(:,:,:), &
Code: Select all
CALL ListGetRealArray( Material,'Heat Conductivity',Hwrk,n, &
Element % NodeIndexes )
HeatConductivity = 0.0d0
IF ( SIZE(Hwrk,1) == 1 ) THEN
DO i=1,3
HeatConductivity( i,i,1:n ) = Hwrk( 1,1,1:n )
END DO
ELSE IF ( SIZE(Hwrk,2) == 1 ) THEN
DO i=1,MIN(3,SIZE(Hwrk,1))
HeatConductivity(i,i,1:n) = Hwrk(i,1,1:n)
END DO
ELSE
DO i=1,MIN(3,SIZE(Hwrk,1))
DO j=1,MIN(3,SIZE(Hwrk,2))
HeatConductivity( i,j,1:n ) = Hwrk(i,j,1:n)
END DO
END DO
END IF
Code: Select all
REAL (KIND=DP), ALLOCATABLE :: Conductivity(:,:,:)
Code: Select all
CALL ListGetRealArray( Model % Materials(k) % Values, &
'Electric Conductivity', Cwrk, n, NodeIndexes )
Conductivity = 0.0d0
IF ( SIZE(Cwrk,1) == 1 ) THEN
DO i=1,3
Conductivity( i,i,1:n ) = Cwrk( 1,1,1:n )
END DO
ELSE IF ( SIZE(Cwrk,2) == 1 ) THEN
DO i=1,MIN(3,SIZE(Cwrk,1))
Conductivity(i,i,1:n) = Cwrk(i,1,1:n)
END DO
ELSE
DO i=1,MIN(3,SIZE(Cwrk,1))
DO j=1,MIN(3,SIZE(Cwrk,2))
Conductivity( i,j,1:n ) = Cwrk(i,j,1:n)
END DO
END DO
END IF
Code: Select all
REAL(KIND=dp) :: Stress(:,:), Strain(:,:), ElasticModulus(:,:,:), &
Code: Select all
Material parameters:
! --------------------
IF ( Isotropic(1) ) Poisson = SUM( Basis(1:n) * PoissonRatio(1:n) )
C = 0
IF ( Isotropic(1) ) THEN
Young = SUM( Basis(1:n) * ElasticModulus(1,1,1:n) )
ELSE
DO i=1,SIZE(ElasticModulus,1)
DO j=1,SIZE(ElasticModulus,2)
C(i,j) = SUM( Basis(1:n) * ElasticModulus(i,j,1:n) )
END DO
END DO
END IF
Anil Kunwar
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
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Re: StressSolver non-linear material
Hi,
The Poisson ratio can be a variable of anything. You can see this by the fact that it is fetched by GetReal() / ListGetReal() function.
The ListGetRealArray(), on the other hand, is used for obtaining tensors. By definition Poisson ratio can never be a tensor since it assumes isotropic material. ListGetRealArray() can also deal with scalars.
-Peter
The Poisson ratio can be a variable of anything. You can see this by the fact that it is fetched by GetReal() / ListGetReal() function.
The ListGetRealArray(), on the other hand, is used for obtaining tensors. By definition Poisson ratio can never be a tensor since it assumes isotropic material. ListGetRealArray() can also deal with scalars.
-Peter
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- Posts: 215
- Joined: 26 Aug 2009, 18:20
- Location: Peterborough, England
Re: StressSolver non-linear material
Hi Elmer team,
Am I correct in assuming, that as the stresssolver stands it is not possible to define a non-linear material?
Regards
Mark
Am I correct in assuming, that as the stresssolver stands it is not possible to define a non-linear material?
Regards
Mark
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- Site Admin
- Posts: 4826
- Joined: 22 Aug 2009, 11:57
- Antispam: Yes
- Location: Espoo, Finland
- Contact:
Re: StressSolver non-linear material
Hi Mark
StressSolver is always linear. ElasticSolver has geometric nonlinearity, and also some nonlinear material law. There is in principle no reason why these could not be in the same solver but they just happen to be two distinct solvers.
-Peter
StressSolver is always linear. ElasticSolver has geometric nonlinearity, and also some nonlinear material law. There is in principle no reason why these could not be in the same solver but they just happen to be two distinct solvers.
-Peter
-
- Posts: 215
- Joined: 26 Aug 2009, 18:20
- Location: Peterborough, England
Re: StressSolver non-linear material
Hi Peter,
Thanks for the reply.
I ran the problem using the ElasticSolver rather than the StressSolver using a Young's modulus with variable strain as posted in my original posting (I also tried with variable stress) but the output still shows linear behaviour;-(
I am simulating a tensile test and want the simulation to produce the non-linear stress/strain curve for the material that I generated the secant modulus data from but without success.
Are there any undocumented features of the ElasticSolver that would allow me to accomplish this? If not could I request that this ability is integrated into the ElasticSolver?
In the past I've had to resort to using Calculix for this type of problem but would prefer to use Elmer as I've put together a set of tutorials for my fellow engineers for thermal, electrostatic and fluid flow using GMSH as the pre-processor and paraview as the post-processor and would like to do the same for structural problems and be applicable for non-linear materials.
Best Regards
Mark
Thanks for the reply.
I ran the problem using the ElasticSolver rather than the StressSolver using a Young's modulus with variable strain as posted in my original posting (I also tried with variable stress) but the output still shows linear behaviour;-(
I am simulating a tensile test and want the simulation to produce the non-linear stress/strain curve for the material that I generated the secant modulus data from but without success.
Are there any undocumented features of the ElasticSolver that would allow me to accomplish this? If not could I request that this ability is integrated into the ElasticSolver?
In the past I've had to resort to using Calculix for this type of problem but would prefer to use Elmer as I've put together a set of tutorials for my fellow engineers for thermal, electrostatic and fluid flow using GMSH as the pre-processor and paraview as the post-processor and would like to do the same for structural problems and be applicable for non-linear materials.
Best Regards
Mark
Re: StressSolver non-linear material
Hi Peter,raback wrote:ElasticSolver has geometric nonlinearity, and also some nonlinear material law. There is in principle no reason why these could not be in the same solver but they just happen to be two distinct solvers.
looking into the ElasticitySolver, i have understood that it is set to be a non-linear elasticity solver by default:
Code: Select all
LOGICAL:: LinearModel = .FALSE.
Code: Select all
Solver 1
...
Elasticity Solver Linear = True
...
End
Code: Select all
LinearModel = ListGetLogical( SolverParams, &
'Elasticity Solver Linear', GotIt )
However, why in ElmerGUI , is it necessary to activate Non linear elasticity in the solver section as
Code: Select all
Nonlinear Elasticity
Active = On
nonlinearelasticity.xml?
Yours
Anil Kunwar
Anil Kunwar
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Faculty of Mechanical Engineering, Silesian University of Technology, Gliwice
Re: StressSolver non-linear material
Hey,
Any update on defining non-linear stress-strain material properties?
I am interested in simulating tensile tests on plastic materials.
Thanks in advance!
Nikos
Any update on defining non-linear stress-strain material properties?
I am interested in simulating tensile tests on plastic materials.
Thanks in advance!
Nikos