April 23, 2024 at 5:44 pm
Chris Quan
Ansys Employee

There are few things you need to check your model setup:

  1. How did you apply the Velocity of 15 m/s? This velocity should be applied using Initial Conditions -> Initial Velocity. The velocity drop of the vehicle indicates the amount of energy absorption by the rubber and foam materials. Constant Velocity Boundary Condition should not be used.
  2. You need to plot Energy Summary from Solution Information in Tree -> Solution Output to check how large the hourglass energy is. If hourglass energy is large comparing with Internal Energy, you need to refine mesh to reduce hourglass energy.
  3. Material rubber should use Hyperelastic material model. Material foam should use one of the porous EOS such as crushable foam to describe its behavior of volume change.
  4. Time step is automatically calculated by the program based upon CFL Stability Criterion. You cannot make it larger than the stability time step.