LS-DYNA聚能射流侵彻靶板问题请教？

聚能射流打靶错误本人在用流固耦合算法打靶时，穿深一半时常出现以下提示：
*** Warning 40114 (SOL+114)
time step decr more than 50% redo cycle 326384

*** Warning 40117 (SOL+117)
negative vol in advection redo cycle 326385

*** Error 40500 (SOL+500)
node # 1 has out-of-range velocities
x-velocity= NaN
y-velocity= NaN
z-velocity= NaN

有没有好心的大佬呀孩子琢磨半年了