True stress vs effective strain curves in ls-dyna

Altair Forum User
Altair Forum User
Altair Employee
edited October 2020 in Community Q&A

Hi,

 

I have a question concerning the Input of true stress vs effective strain curves in ls-dyna:

 

I would like to insert several curves for different strain rates for MAT_24 using the table Option, because I dont know the Cowper-Symonds constants.

These curves are from experiments and range from the yield point up to the ultimate tensile stress.

The remainder is missing and that is why I have used the voce equation for it. Does it make sense to insert several Points using 'Load xy Data' or just up to 8 Points?

 

I plan on crushing a thin walled tube of AA6060.

 

 

Greetings,

Friendly

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Answers

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

    Hi @Friendly

     

    Since this related LsDyna solver input, I would suggest you get in touch with Dyna support. 

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

    I think it works. the yield point is the beginning of plastic process. the load curve should start with a plastic strain=0 and a plastic stress=yield stress. Of course you should make a transfer to the effective stress and effective plastic strain.

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

    Hi thanks for your answer! Do you know whether it is better to put in effective stress vs. effective plastic strain up to the ultimate stress Point or to extrapolate the remaining curve with a voce-equation? The Problem with the voce-equation is, that my material becomes very ductile for some reason.

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