ansys 螺栓预紧力分析报错

*** ERROR ***                           CP =      22.480   TIME= 22:45:48

 The value of UY at node 5989 is 476303840.  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.                                                   

 *** ERROR ***                           CP =      22.620   TIME= 22:46:04

 *** MESSAGE CONTINUATION ---- DIAGNOSTIC INFORMATION ***                

 If one or more parts of the model are held together only by contact     

 verify that the contact surfaces are closed.  You can use the CNCHECK   

 command to check the initial contact status in the SOLUTION module.     

这是在ANSYS中进行螺栓预紧力分析，出现以上两处错误，不知道是接触问题还是边界条件问题或者是预紧力的加载不对，恳请有经验或懂的大神指点一下，谢谢！