PrePoMax supports CalculiX’s dynamic analyses - implicit or explicit dynamic step. The latter is normally better for impact simulations but it can be difficult to make it work properly because of its not-so-good implementation in CalculiX. You can try both step types though, possibly using a simple model first. Of course, you will have to define contact between the parts that are supposed to collide.
OpenRadioss is much better for explicit dynamics (simulations involving impact/crash) but it doesn’t have easy to use preprocessor.