Plastic strain

Karthic_22061
Karthic_22061 Altair Community Member
edited October 2020 in Community Q&A

Hi,

I am trying a simple NLGEOM case in Optistruct with Plastic part , using global output request strain >> Extra>> plastic to output plastic strain to h3d.

 

But i dont get any plastic strain results in plot?  i tried increasing loads but always the plastic strain remains Zero

 

 

 

<?xml version="1.0" encoding="UTF-8"?>strain plot.PNG

<?xml version="1.0" encoding="UTF-8"?>material.PNG

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Answers

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Hi,

     

    Can you share the model file, please?

  • Karthic_22061
    Karthic_22061 Altair Community Member
    edited January 2018

    Hi Prakash,

    File shared through link.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited January 2018

    Thank you for sharing the file.

     

    As it is taking time, can you check what the stress is?

     

    Also the out file you shared is for starter. Please share engine .out file.

  • Karthic_22061
    Karthic_22061 Altair Community Member
    edited January 2018

    Hi Prakash,

    Thank you for the support

    Shared engine out and stress plot

    <?xml version="1.0" encoding="UTF-8"?>stress.png

    Unable to find an attachment - read this blog

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi,

     

    From the curve it looks like material is still below yield point. 

     

    I am attaching a sample curve along with your curve. Please let me know If I am missing anything.

     

    What type of material is it? At first look I assumed the curve is for concrete material. 

    <?xml version="1.0" encoding="UTF-8"?>NLCurve.PNG

  • Karthic_22061
    Karthic_22061 Altair Community Member
    edited February 2018

    HI prakash,

    Its PA6( plastic material)

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    OK, I will check and update you soon on this. 

  • Nachiket Kadu_22143
    Nachiket Kadu_22143 Altair Community Member
    edited February 2018

    Hi

    Kindly check for material card Mat S1, whether you have mentioned Plastic or NLelastic. For NL elastic i guess it wont show plastic strains.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    During B2B plastic strains are converted to epsp to RADIOSS. EPSP is not available for brick elements and this isnwhy you dont see plastic strain. 

  • Nachiket Kadu_22143
    Nachiket Kadu_22143 Altair Community Member
    edited February 2018

    Hi

    You are saying this for only brick elements or solid elements in totality?

    What is B2B u are referring here?

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    B2B= Bulk to Block. So NLGEOM from OptiStruct is converted to RADIOSS solver file in the back ground.

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    I agree with @Nachiket Kadu that NLELAST will not write out plastic strain as NLELAST means non-linear elastic and will not have plastic values

  • Karthic_22061
    Karthic_22061 Altair Community Member
    edited February 2018

    Thankyou Prakash & Nachiket.  If Plastics option to be used instead of NLELAST, whether my table data should start 0,0 or 0,yield stress... 

  • Altair Forum User
    Altair Forum User
    Altair Employee
    edited February 2018

    Hi @Karthic

     

    From OptiStruct help:

    If TYPE = PLASTIC, the curve must be defined in the first quadrant. The data points must be in ascending order. If the table is defined in terms of total strain (TYPSTRN=0), the first point must be at the origin (X1=0, Y1=0) and the second point (X2, Y2) must be at the initial yield point (Y1) specified on the MATS1 entry.

  • Karthic_22061
    Karthic_22061 Altair Community Member
    edited February 2018

    Thank you  Prakash

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