abaqus 四点弯曲使用刚体施加载荷出现以下问题请问怎么解决？

***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE 

             PART-3-1.1 D.O.F. 2. THIS NODE HAS NO STIFFNESS IN THE SPECIFIED 

             DIRECTION AND IS NOT COUPLED WITH THE REST OF THE MODEL.