LS Dyna

LS Dyna

Very slow movement

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    • santiagosep1706
      Subscriber

      I'm simulating a dynamic problem where the velocity is very slow, 0.17 mm/s. What recommendation could you give to obtain a result using a dynamic analysis in workbench.

    • peteroznewman
      Subscriber
      If the velocity is very slow, solve the model in Static Structural. Solving in Dynamics adds a term to the equation, which is the inertial forces of mass x acceleration. If the acceleration is zero, the force is zero and the equation is like a statics equation.
      Maybe the reason you are solving in Explicit Dynamics is because it makes computing self contact easy or it makes element erosion easy. If the issue is the solution time is very long due to the slow velocity, then the answer is to increase the velocity. As long as the kinetic energy remains a very small fraction of the total energy, the result will be quasi-static.
    • santiagosep1706
      Subscriber
      Thanks but in static structural I can't add a component in one element of the assembly

    • peteroznewman
      Subscriber
      What do you mean you can't add a component in one element of the assembly?
    • santiagosep1706
      Subscriber
      Thanks but in static structural I can't add a velocity in one element of the assembly
    • peteroznewman
      Subscriber
      You can apply displacement to one part of an assembly in static structural.
      Please explain why it has to be velocity and not displacement. It would be easier help if you described the model.
    • santiagosep1706
      Subscriber
      I'm trying to simulate a quasi-static punch shear test.
      The movement of the punch to penetrate the material.


    • peteroznewman
      Subscriber
      The reason you are solving in Explicit Dynamics is because it makes computing element erosion easy. The issue is the solution time is very long due to the slow velocity.
      The answer is to increase the velocity. As long as the kinetic energy remains a very small fraction of the total energy, the result will be quasi-static.
      Look at the Energy Probe results for the body being punched.
      Internal Energy + Plastic Work should be orders of magnitude larger than Kinetic Energy.

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