Generally, ANSYS files are not backward compatible. However, the ANSYS Autodyn restart files (files with the extension of .ad) can be saved to the files of the last three previous releases. For example, an Autodyn restart file “admodel.ad” which is created in R19 can be saved as version in R18, R17, and R16 using Autodyn GUI in the Autodyn Component System. Autodyn results files (files with the extension of .adres) are used only for storing results and are not used for running, thus the results files cannot be saved backwards. If using Autodyn started from within Workbench, see the option Files -> Export As Version. If using Autodyn started outside of Workbench, see the option Files -> Save As Version.