pb in a run

Lionel THOLLON
Lionel THOLLON New Altair Community Member
edited November 2020 in Community Q&A

Hi,

I have successive message during my run : "WARNING ZERO OR NEGATIVE SUB-VOLUME : 3D-ELEMENT ID : 29874885     ELEMENT IS SWITCHED TO SMALL STRAIN OPTION"


and at the end the run is killed with the message : "MESSAGE ID :        207   ** RUN KILLED : TOTAL MASS ERROR LIMIT REACHED".


What is exactly the signification of the first message ? I thought that it is necessary to choice the option Ismstr 2 for 3D tetra element in the property to switch in small strain formulation. I did not used this option, I kept the Ismstr 0 (default value) but I have this message.

Why is my run killed ?

Thank you in advance for yours answers

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Answers

  • Adriano Koga_20259
    Adriano Koga_20259 New Altair Community Member
    edited October 2020

    You should better check what is going on close to this element mentioned by RADIOSS, ID 29874885

    There is something that is causing a large deformation of this element, thriggering this chance in formulation in the middle of your run to try to accomodate this large distortion.

    Due to the excessive element distortion your timestep is decreasing a lot, and RD is trying to compensate by adding mass to your element/node, but your mass error reached the limit.

  • Lionel THOLLON
    Lionel THOLLON New Altair Community Member
    edited October 2020
    Adriano Koga_20259 said:

    You should better check what is going on close to this element mentioned by RADIOSS, ID 29874885

    There is something that is causing a large deformation of this element, thriggering this chance in formulation in the middle of your run to try to accomodate this large distortion.

    Due to the excessive element distortion your timestep is decreasing a lot, and RD is trying to compensate by adding mass to your element/node, but your mass error reached the limit.

    In fact around the element (and other elements close to it) I have an impactor that induce these large deformations. I would like to simulate correct deformation without decrease the velocity of the impact. Do you have an idea to do this ? Perhaps a specific option in the property of tetrahedrals elements ?

  • Juan_Pedro_Berro
    Juan_Pedro_Berro
    Altair Employee
    edited November 2020

    Hi Lionel,

     

    That can produce for plastic behavior with perfect plasticity (for exemple) or very soft material under compression.

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