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LS Dyna

Topics related to LS-DYNA, Autodyn, Explicit STR and more.

The impactor doesn’t see the SPG particles.

    • javat33489
      Subscriber

      Hello everyone. I'm simulating an impact.
      One element hits another, and it hits the SPG particles—the concrete. But the body passes through the particles. It worked before. Why did it break? I'm attaching a screenshot of the contact, as well as an image of how the particles should fly apart.

       

    • Ram Gopisetti
      Ansys Employee

      Hi, 

      I don’t believe this issue is related to contact. However, you can try increasing the stiffness parameters using SFSA and SFSB. It is also advisable to set the STRETCH value in SECTION_SPG to 1.01 when modeling with materials mat72, mat84, mat96, mat111, mat159, mat272, and mat273. Adjust this value as necessary, followed by fine-tuning the FS parameter.

      Additionally, set the Dilation parameter to 1.6, KERNAL to 2, SMSTEP to 30, and IDAM to 1.

      For improved evaluation of the model, it is recommended to render the SPG mesh as particles, which provides a clearer visual assessment of the cross-section.

      Cheers, Ram 

      • javat33489
        Subscriber

        Thanks sir I'll try!

      • javat33489
        Subscriber

        Sir. All DILATIONs?

      • javat33489
        Subscriber

        Sir I am using MOHR-COULOMB model for concrete:

         

        Why don’t I see cracks and the material crumble from impact? because I use SPG?


        My cylindrical concrete blank is fixed around the entire perimeter

         

    • Dennis Chen
      Subscriber

      I am relatively sure you need a much higher density of particles.   You can check the documentation/literature for more detail about how the particle sees each other.    I am not going to say more because I am by no means an expert on SPG but I think it's smart just to do some mesh sensitivity studies. 

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