Questions regarding bcc analysis and FIPs calculation in prisms-plasticity and prisms-fatigue

[Itsuki Fujita]

Dear PRISMS team,

I have some questions regarding prisms-plasticity and prisms-fatigue.
I would like to perform CPFEM analyses and FIPs calculations for bcc structures, mainly focusing on steel materials.

Based on my understanding, I have summarized the following points. Could you please let me know if my understanding is correct?

• Slip system definitions can be set using SlipDirections.txt and SlipNormals.txt, and recompilation from fcc to bcc is not necessary.
• The sample case simpleTension defines 12 slip systems based on the {110}<1 -1 1> family.
• FIPs calculation does not require modifications to updateAfterIncrement.cc or calculate_FIPs.py because the default settings in prisms-fatigue are already designed to handle output for 12 state variables.
• If I want to calculate other slip families such as {112} or {123} for bcc structures, it is sufficient to add them in SlipDirections.txt and SlipNormals.txt for prisms-plasticity. However, for FIPs calculation, I would need to modify updateAfterIncrement.cc and calculate_FIPs.py according to the total number of slip systems.

I would appreciate it if you could confirm whether my understanding is correct.

Best regards,
Itsuki

[Krzysztof Stopka]

Hi Itsuki,

This all sounds correct. Chaitali, can you please confirm?

Best regards,

Krzysztof Stopka

[Chaitali Patil]

Hi Itsuki, 

Yes, above points sounds correct. 
Just  reminder to also accordingly increase the number of state variables defined in the prm file. 
set Number of User Material State Variables 1        = 62 

Regards,

Chaitali 

[Itsuki Fujita]

Hi Krzysztof, Chaitali,

Thank you for checking.
It seems that some definitions were indeed missing in my prm file.
Below is an excerpt from the FreeSurface_Effect_Al7075T6.prm file — is this the section you were referring to?

I understand that when considering 12 slip systems, the number of material constants is 13 and the number of state variables is 62, and these numbers do not change.

However, do these 13 material constants need to be changed depending on whether the material is fcc or bcc, or depending on the specific material?
Could you also explain what each of these 13 constants represents, and recommend any literature or documentation where I could find how to determine appropriate values?

Thank you in advance for your help.

Best regards,
Itsuki

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# Flag to indicate if User Material Model is enabled
set Enable User Material Model                   = true

# Flag to indicate if User Material Model is enabled Phase 1
set Enable User Material Model 1                  = true

# Number of User Material Constants in a Material model Phase 1
set Number of User Material Constants 1              = 13

# Number of User Material State Variables in a Material model Phase 1

set Number of User Material State Variables 1        = 62

# Material Constants in a Material model Phase 1
set User Material Constants 1             = 1

# Material State Variables Initial Values in a Material model Phase 1
set User Material State Variables Initial Values 1       =

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2025年3月19日水曜日 22:38:56 UTC+9 Chaitali Patil: