LS Dyna

LS Dyna

Simulation timestep getting very small and freezes but I don’t get any error or warning?

    • Conorryan98

      I'm running a hypervelocity impact simulation using SPH as seen below. The timestep gets very small until the projectile doesn't progress any further, although the cycle keeps increasing, the time and timestep don't change anymore.

      Does anyone know why this is?

    • Chris Quan
      Ansys Employee
      The cycle information on the bottom of the Autodyn window shows that the time step is controlled by SPH particles.
      I would suggest you plotting the Vector plot of the velocity to check the velocity of SPH particles. Some SPH particles may have a very high velocity due to material failure.
      If this is true, you can put a limit on the maximum velocity (default is 1E10 m/s) via Controls -> Cutoff and set the Maximum Velocity to a reasonable value such as 2 or 3 times of the impact velocity.
      This will limit the SPH maximum velocity to a reasonable value and thus increase the time step.
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