Figure 7.20: Rotation of Results by RSYS
xy(a)Defaultorientation-
paralleltoglobal
Cartesiansystem(C.S.O.)
UYUXxy11(b)Rotatedparalleltolocal
cylindricalsystem
(RSYS,11)UY UXxy11(c)Rotatedparalleltoglobal
cylindricalsystem
(RSYS,1)UXUYCautionCertain element results data are always output in the element coordinate system regardless
of the active results coordinate system. These are miscellaneous result items that you would
normally expect to be interpreted only in the element coordinate system. They include forces,
moments, stresses, and strains for beam, pipe, and spar elements, and member forces and
moments for some shell elements.In most circumstances, such as when working with a single load case or during linear combinations of
multiple load cases, rotating results data into the results coordinate system does not affect the final
result values. However, most modal combination techniques (PSD, CQC, SRSS, etc.) are performed in
the solution coordinate system and involve squaring operations. Since the squaring operation removes
the sign associated with the data, some combined results may not appear as expected after being rotated
into the results coordinate system. In these cases,RSYS,SOLU is on by default in order to keep the
results data in the solution coordinate systems. No other coordinate system may be used.
As an example of when you would need to change the results coordinate system, consider the case of
a cylindrical shell model, in which you may be interested in the tangential stress results. The SY stress
contours before and after results coordinate system transformation are shown below for such a case.
PLNSOL,S,Y! Display a: SY is in global Cartesian system (default)
RSYS,1
PLNSOL,S,Y! Display b: SY is in global cylindrical systemSee the RSYS and PLNSOL command descriptions for further information.
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