Is there any mechanical simulation (FEA) software that is capable of simulating the intricacies of the additive manufacturing process (aka 3D printing)?
I want to be able to simulate how different patterns of material (thermoplastics like ABS or PLA) deposition affect the part strength and flexibility. Bonus points if the software is able to import the gcode output from the slicer.
If there's none, what's the closest solution that I can get?
I suspect this is much too complicated to be a "standard analysis option" in a FEA package. You might have to consider effects like porosity of the material deposited by the printer, locked-in stresses caused by thermal expansion, chemical and phase changes in the material caused by the temperatures involved, etc, etc ....
I've never had to be concerned about the mechanical properties of structures printed from plastics, but I would expect the best option is to find some measured material properties for a similar printing method, and be aware of any guidelines on avoiding problems (for example the best practice to avoid excessive weakening of thin sections)
A long time ago I was involved with a similar question about metal components built by deposition - the process was similar to "building up the shape of the component entirely from welding wire". FWIW, we found (by testing) that the final material properties were similar to manufacturing the component by casting.