Learning Forum

[langlinator]

Hi,

I have piece-wise non-linear stress-strain data, that I need to input to Ansys. It seems like the "Multilinear elasticity" model is most suitable, as you can enter piece-wise data. I know this unloads along the original path, and that is not a problem, as I do not need to consider unloading. As Multilinear Elasticity is not available in Workbench, I'm working in MAPDL (unfamiliar for me).

I am having trouble getting the Multilinear Elasticity (MELAS) model to work. I keep getting error messages.

When setting up the MELAS table (via GUI):

Can anyone provide more detail on what this error means?

[Vitaliy_Degtyarev]

MELA does not seem to be currently supported. You may want to look into plasticity models at this link:  https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v192/ans_mat/amp8sq21dldm.html

I usually use the Multilinear Isotropic Hardening model with plasticity similar to the one shown below to describe a nonlinear stress-strain diagram of steel.

Example 4.5: Multilinear Hardening with Plastic Strain

/prep7

MPTEMP,1,0,500            ! Define temperature-dependent EX
MPDATA,EX,1,,14.665E6,12.423e6

MPDATA,PRXY,1,,0.3



TB,PLASTIC,1,2,5,MISO     ! Activate TB,PLASTIC data table

TBTEMP,0.0                ! Temperature = 0.0

TBPT,DEFI,0,29.33E3       ! Plastic strain, stress at temperature = 0

TBPT,DEFI,1.59E-3,50E3

TBPT,DEFI,3.25E-3,55E3

TBPT,DEFI,5.91E-3,60E3

TBPT,DEFI,1.06E-2,65E3

TBTEMP,500                ! Temperature = 500

TBPT,DEFI,0,27.33E3       ! Plastic strain, stress at temperature = 500

TBPT,DEFI,2.02E-3,37E3

TBPT,DEFI,3.76E-3,40.3E3

TBPT,DEFI,6.48E-3,43.7E3

TBPT,DEFI,1.12E-2,47E3

Regards,

Vitaliy

[nitinansys1995]

sir , as i want to do soil modelling in ansys workbench . so there are four mechanical model in ansys for soil modelling and defaultly soil properties is given as per cam-clay model . as i added soil to my project i m not getting solution . so i added  mohr coloumb properties for soil modelling but again i am not getting any results so sir can you guide me how to know what are the intial steps for this typer of analysis in ansys workbench. here i am attaching some of the images of my work .  i am thankful fort your support 

[Vitaliy_Degtyarev]

nitinansys1995,

I'm not an expert in Ansys Workbench nor in soil material modeling, Perhaps, a discussion at this link will help you: /forum/forums/topic/soil-modeling/

Regards,

Vitaliy

 

[langlinator]

I don't understand, why would MELA be available in the MAPDL software if it is not supported?

 

[Vitaliy_Degtyarev]

I do not know and I may be wrong, but I do not see MELA as one of the material data table types listed in ANSYS Help at these links: https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v192/ans_cmd/Hlp_C_TB.html, https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v192/ans_mat/Mp8sasdgh.html

The link below lists TB,MELAS as legacy material properties.https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v192/ans_arch/mela.html?q=MELA

An article at this link may help you: https://www.padtinc.com/blog/using-external-data-to-utilize-legacy-mechanical-apdl-models-in-ansys-workbench/

[langlinator]

Thank you for the further advice

 

It is strange that MELAS shows as legacy for you. I am using 2019 R2 student, and when I access the help materials via the links in the software, it shows as a current model:

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/ans_mat/mat_multilinelas.html

and also having elements that support it:

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/ans_mat/Mp8sasdgh.html

[langlinator]

Edit: Somehow I got into the 2020 R1 help, I checked the 2019 R2 help and have the same indications.

When I access the help materials via the links in the software, it shows as a current model:

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v194/ans_mat/mat_multilinelas.html

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/ans_mat/mat_multilinelas.html

and also having elements that support it:

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v194/ans_mat/Mp8sasdgh.html

https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v201/en/ans_mat/Mp8sasdgh.html

PLANE182 (plane strain or axisymmetric), PLANE183 (plane strain or axisymmetric), SOLID185, SOLID186, SOLID187, SOLSH190, SOLID272, SOLID273, SOLID285, PIPE288, PIPE289

 

[langlinator]

Result: despite the error message, I am getting results that are consistent with my input MELAS data using element SOLID185.

[Vitaliy_Degtyarev]

You are right. I'm still using v.19.2 where MELAS is listed as a legacy material model. I see it as a current model in the later ANSYS versions. Sorry about the confusion.