In what coordinate system are element stresses reported for SHELL elements?
In Release 10.0, the coordinate system in which the stress results are reported is controlled by the RSYS command. By default the results are reported in the global Cartesian system (RSYS,0). If RSYS,SOLU is issued, the results are reported in the solution coordinate system. The solution coordinate system for SHELL elements is the element coordinate system. So, if RSYS,SOLU is issued, the stress results are reported in the element coordinate system.
The input file demonstrates this behavior. The element coordinate system for the elements in AREA 2 is rotated 90 degrees in the XY plane. From the printout you can see that the X and Y stress results are identical unless RSYS,SOLU is issued, then SX and SY are reversed.