用弧长法，求解稳定问题

incorporated

用弧长法，求解稳定问题，不断出现“刚体位移”，就是warning:The value of ROTX at node 10222 is 305132710.  It is greater than the   current limit of 1000000.  This generally indicates rigid body motion   
as a result of an unconstrained model.  Verify that your model is    properly constrained.     请问高手怎么设置弧长半径为合适值，我试了很多值了。