USDFLD and automatic time incrementation

[ardalansv]

I am using a USDFLD subroutine for my FE analysis. I wanted to know if I can use USDFLD subroutine with the automatic time incrementation? I have read in the documentation that PNEWDT is allowing the subroutine to work with automatic incrementation but I wanted to be sure if I need to define any number for PNEWDT or just stating it in the USDFLD interface like below is enough and Abaqus itself will take care of it?

SUBROUTINE USDFLD(FIELD, STATEV, PNEWDT, DIRECT, T,
1 CELENT, TIME, DTIME, CMNAME, ORNAME, NFIELD,
2 NSTATV, NOEL, NPT, LAYER, KSPT, KSTEP, KINC, NDI,
3 NSHR, COORD, JMAC, JMATYP, MATLAYO, LACCFLA)
...

Regards,
Ardalan

 

[Mustaine3]

I've never used this subroutine, but based on the manual and the example in there, I think that the definition of PNEWDT is optional.

 

[IceBreakerSours]

Yes, you can use USDFLD with automatic time incrementation. PNEWDT is a variable that can be updated, but need not be updated if the application does not require it.

What are you trying to accomplish? What is the application?

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[ardalansv]

Thank you so much for your quick replies. Dear Mustaine3 it says it is optional but if the automatic incrementation is selected it should be there.

Dear IceBreakerSours I am trying to use it for expanding the elements by comparing the stresses in the model to an initial stress during the step. However, I have one more issue which is reading and writing the stresses in the local direction to compare it to the initial stress, which I haven't been able to do it so far.

Regards,
Ardalan

 

[IceBreakerSours]

Why are you expanding the elements? I am probing to understand why you chose USDFLD. Are you trying to implement tissue growth or an adaptation algorithm?

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[ardalansv]

IceBreakerSours yes that is what exactly I want to do.

 

[IceBreakerSours]

Assuming you are a student, talk to Abaqus and see if they can share their bone remodeling code with you and save you time. Or, at the very least, find out what it would take for Abaqus to share it with you.

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[IceBreakerSours]

Also, I bet several researchers have done this already. Why spend time on something others have done years, if not decades, ago? Just get in touch with them and ask them if they wouldn't mind sharing their code with you so you can do something novel.

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