Ushnish Basu
Ansys Employee

There are two different issues here:

  1. The non-zero static displacement is of concern, as it won't be supported by the absorbing boundary. Please make sure that your acceleration is baseline-corrected.
  2. I can't see the jaggedness of the output from the picture, but you can try reducing the output timestep in LS-DYNA to get a smoother curve