Before Fusion 360 I used Mecway for all FEA work when I needed it. It would be cool if it was possible to use external solvers inside of fusion as it already has really nice Pre and Post processing and integration with models.
Adding an external solver like CalculiX would open up a lot of simulation capibilities.
For referance on capibilities.
Mecway - http://mecway.com/product.html
CalculiX - http://www.dhondt.de/ov_calcu.htm