Assigning different material at every time step in Abaqus

[abdu90]

Hello,

Is there is a way to assign different material sections at every time step in Abaqus/Explicit ? For example at time step 1, I want to assign steel-1 and at time step 2 I want to assign steel-2 .... and going on. I know that it is possible to write a script by python to have different material section. However, how can I but a criteria for the time increment or step ?

Thanks,

 

[Mustaine3]

You cannot change the material assignment within one simulation. You could only change the material parameters when adding dependency to field variables or temperatures.

 

[FEA way]

There have already been a few discussions on this topic here. Check this thread, it might be helpful:

https://www.eng-tips.com/viewthread.cfm?qid=259881

 

[abdu90]

Thank you both for your prompt reply's. @ FEA this thread is discussing different issue, he wants to assign different material sections at different steps. @ Mustaine3 yes I have tried that but the problem is that for each time step I have 20 values of young's modulus (it varies with length). Can it be done with only one material definition ?

 

[Mustaine3]

If your problem does not include thermal DOF, then you can use one field variable and the temperature to define the dependencies in space and time.

But maybe it's easier to use multiple field variables and modify them with the subroutine UFIELD.

 

[FEA way]

This should be closer to what you want to achieve if your goal is time-varying Young's modulus:

https://www.eng-tips.com/viewthread.cfm?qid=459126

 

[abdu90]

I have tried to implement what you are suggesting using VUSDFLD as I am using explicit solver, but I faced a problem. When I increase the number of fields to 6 and above as shown in the figures bellow the job aborts and it gives this error message.
---------- RUNTIME EXCEPTION HAS OCCURED ----------
*** ABAQUS/package_dp rank 0 encountered a SEGMENTATION FAULT
---------- RUNTIME EXCEPTION HAS OCCURED ----------

package.exe / rank 0 / thread 0 encountered a system exception 0xC0000005 (EXCEPTION_ACCESS_VIOLATION)

---------- RUNTIME EXCEPTION HAS OCCURED ----------

package.exe / rank 0 / thread 0 encountered a system exception 0xC0000005 (EXCEPTION_ACCESS_VIOLATION)

 

[FEA way]

How do you submit the job - cluster, parallel computing ? What is your operating system and Abaqus version ?

Also, why did you add so many field variables ?

 

[abdu90]

Yes I am using Parallel computing. I am submitting the job using Abaqus user interface, I have also tried using Abaqus command but I faced the same problem. I am using windows 10 (Abaqus 2020).

Regarding the field variables, I have so many because I wanted to relate time and space. To do that I wrote a subroutine if the time step = 1 use field 1, if the time step = 2 use field 2 and going on. The number of fields here is equal to the number of the time span. For my analysis I need 20s;hence 20 fields.

Thank you,

 

[FEA way]

Often the subroutine is what caused these types of errors. Either because of mistakes in code or because of problems with compiling on a particular machine. Have you tried running any other subroutines before ?

 

[abdu90]

Yes I have. I have also tried this one (see attached ) but for less number of fields and it worked. I don't believe there is problem in the code because I tried to run the model with an empty subroutine code and still the model with high fields didn't work. Maybe it is a memory problem ? if yes do you know how it can be fixed?