Learning Forum

[Emilie Henning]

Hello, 

I am creating a simulation where I'd like to use either the cast iron plasticity or crushable foam material models. In these simulations, there are different sets of elements that all use the same material model but with different parameters. I'm having an issue with both models where if I have more than one element set, I get an error "For material 2, TB,,CAST,,, ISOTROPIC table requires 1 parameter. 2 have been defined" or "TB,CFOAM,,,YIELD has already been defined. Please delete existing table to overwrite." If I'm only using one material set, this issue does not occur.

FYI, I am coding this up into an ANSYS input deck using APDL. Below is the part of the code I am referencing.

For Cast Iron:

ET,1,SOLID185,,
!
!
!
MP,EX,1,1.050e+02
MP,DENS,1,5.000e-02
MP,PRXY,1,0.381000E+00
!
!
MAT,1
!
TB,CAST,1,,,ISOTROPIC
TBDATA,1,0.3
!
!
TB,UNIAXIAL,1,1,3,TENSION
TBPT,,0,0
TBPT,,4.762e-03,5.000e-01
TBPT,,2.000e+01,5.000e-01
!
!
TB,UNIAXIAL,1,1,3,COMPRESSION
TBPT,,0,0
TBPT,,9.524e-04,1.000e-01
TBPT,,2.000e+01,1.000e-01

then the list of elements included in this material set, then defining second material set

ET,2,SOLID185,,
!
!
!
MP,EX,2,3.150e+02
MP,DENS,2,1.500e-01
MP,PRXY,2,0.381000E+00
!
!
MAT,2
!
TB,CAST,2,,,ISOTROPIC
TBDATA,2,0.3
!
!
TB,UNIAXIAL,2,1,3,TENSION
TBPT,,0,0
TBPT,,4.762e-03,1.500e+00
TBPT,,2.000e+01,1.500e+00
!
!
TB,UNIAXIAL,2,1,3,COMPRESSION
TBPT,,0,0
TBPT,,4.889e-03,1.540e+00
TBPT,,2.000e+01,1.540e+00

then the elements in the material set and so on.

 

Is there a reason I'm getting these errors?

 

Thank you

 

 

[Ashish Khemka]

Hi Emilie,

The error message "for material 2, TB,,CAST,,, ISOTROPIC table requires 1 parameter. 2 have been defined" means that there is an error in defining the material properties for the second material in your simulation model. The error specifically refers to the definition of the isotropic thermal expansion coefficient (TB) for the material. The message suggests that you have defined two parameters for TB, whereas it only requires one parameter to be defined. 

The error message "TB,CFOAM,,,YIELD has already been defined" means that there is a duplicate definition of the material property TB for the material CFOAM in your simulation model. This could be because of material properties have been defined twice for the same material.

 

Regards,

Ashish Khemka

[Emilie Henning]

Hi Ashish, 

Thank you for your reply. I do know what the error messages mean. The issue I'm having is I'd like to use the same material model multiple times with different parameters for each material set. When I define the material model for the first material set, there is no error message. The code below is how I do that:

ET,1,SOLID185,,
!
MP,EX,1,1.050e+02
MP,DENS,1,5.000e-02
MP,PRXY,1,0.381000E+00
!
MAT,1
!
TB,CAST,1,,,ISOTROPIC
TBDATA,1,0.3
!
TB,UNIAXIAL,1,1,3,TENSION
TBPT,,0,0
TBPT,,4.762e-03,5.000e-01
TBPT,,2.000e+01,5.000e-01
!
TB,UNIAXIAL,1,1,3,COMPRESSION
TBPT,,0,0
TBPT,,9.524e-04,1.000e-01
TBPT,,2.000e+01,1.000e-01

 

But when I go to define the same material model, but with different parameters for the second material set, I get the "for material 2, TB,,CAST,,, ISOTROPIC table requires 1 parameter. 2 have been defined" error. Here is the code I use to do that part:

ET,2,SOLID185,,
!
MP,EX,2,3.150e+02
MP,DENS,2,1.500e-01
MP,PRXY,2,0.381000E+00
!
MAT,2
!
TB,CAST,2,,,ISOTROPIC
TBDATA,2,0.3
!
TB,UNIAXIAL,2,1,3,TENSION
TBPT,,0,0
TBPT,,4.762e-03,1.500e+00
TBPT,,2.000e+01,1.500e+00
!
TB,UNIAXIAL,2,1,3,COMPRESSION
TBPT,,0,0
TBPT,,4.889e-03,1.540e+00
TBPT,,2.000e+01,1.540e+00

 

As you can see, for each material (material 1 and material 2), I only have one parameter in the table attached to the cast iron model definition (highlighted in the above information).

 

Is there a way to use the same material model, but with different parameters, for different material sets throughout the model?

 

Thank you!

[Sheldon Imaoka]

Hi Emilie,

For the second material, your TBDATA command syntax seems to be incorrect.

For TBDATA, the first argument is the 'starting location' of your input (not material ID, as the material ID is specified by the preceding TB command).  So by having TBDATA,2,0.3, you are telling MAPDL that the second parameter has a value of 0.3, but there is only one parameter (plastic Poisson's ratio).  In your snippet above, please change the following section (note "TBDATA,1,0.3" is what has changed), and it should run:

MAT,2
!
TB,CAST,2,,,ISOTROPIC
TBDATA,1,0.3
!

Regards,
Sheldon

 

[Emilie Henning]

Hi Sheldon, 

Thank you so much! This has fixed the issue for the cast iron plasticity material model. However, ideally I would like to use the crushable foam model but I am still encountering the "TB,CFOAM,,,YIELD has already been defined. Please delete existing table to overwrite." error when I try to use it. 

This is the code I'm working with for the crushable foam material model:

For material 1: 

MAT,1
!
ET,1,SOLID185,,
!
MP,EX,1,9.679e+02
MP,DENS,1,5.000e-01
MP,PRXY,1,0.381000E+00
!
TB,CFOAM,,1,,,YIELD
TBDATA,1, 1.170e+01, 9.360e+00, 7.488e+00

 

For material 2:

MAT,2
!
ET,2,SOLID185,,
!
MP,EX,2,3.098e+03
MP,DENS,2,1.500e+00
MP,PRXY,2,0.381000E+00
!
TB,CFOAM,,2,,,YIELD
TBDATA,1, 3.660e+01, 2.928e+01, 2.342e+01

Thank you for your help!

[Sheldon Imaoka]

Hi Emilie,

Thanks for your reply.

For your second issue, I think you have an extra comma for TB,CFOAM,,1,,,YIELD.  It should be TB,CFOAM,1,,,YIELD - notice the single comma between "CFOAM" and the material ID number ("1" or "2").  Without this, the material ID may default to the same number, so the second time you issue TB,CFOAM, MAPDL thinks you are redefining the same material ID since the material ID field is left blank.

Regards,
Sheldon

 

[Emilie Henning]

Hi Sheldon, 

Thank you so much, that has fixed my problem. I must have switched that around when doing some earlier troubleshooting. Your help has been instrumental!

Thanks again, 

Emilie