***ERROR: THE PROBLEM IS TOO LARGE TO RUN WITH Abaqus. TYPICALLY THIS IS 

           CAUSED BY THE EXISTENCE OF A VERY LARGE ELEMENT SUCH AS A 

           SUBSTRUCTURE WITH A LARGE NUMBER OF RETAINED DOF, A LARGE CAVITY IN 

           A CAVITY RADIATION PROBLEM, OR SURFACE-BASED COUPLING WITH A LARGE 

           NUMBER OF COUPLING NODES.

这是由于什么原因造成的？捷俊这类问题的途径有哪些？谢谢