abaqus分析过程中出现in keyword *ELSET, file "change.inp", line 18196: Period cannot be used within set, surface, orientation, instance, and assembly names in a model defined in terms of an assembly of parts。请问是什么原因？要怎么进行处理？我运用HyperMesh软件进行网格划分并赋予材料等其他操作，最后导入abaqus直接分析，出现上述错误，请教？急