Ansys won’t import Abaqus files written in the assembly format.The Abaqus file will have lines such as *Assembly, and several *Instance lines after that. There will be multiple *Part sections, each containing a *Node and *Element section. The node and element IDs will begin at 1 for each section, and Ansys won’t allow the duplicate ID’s. You can write out from Abaqus in a flattened format. Another solution is to separate each *Node, *Element section of each *Part into a separate file. Use Multiple External Model systems linked to one downstream Mechanical Model system (Ansys model assembly mode). If you want to retain the *nset and *elset sections, move them to the appropriate file for the part instance they reference and delete the instance terminology after the *nset and *elset commands.