For more on this topic, see Section 5.1, "Stress Initialization for Spinning Bodies", in the 
Modeing Guidelines document availabe at 
http://awg.lstc.com/tiki/tiki-index.php?page=MGD.

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Files in http://ftp.lstc.com/anonymous/outgoing/jday/spinupbar.tar
illustrate 3 different methods of preloading a spinning rotor/blade.

1.  Explicit dynamic relaxation:  preload and explicit all in one.

ls971d   i=spinup.bar.expl_dr.k


2.  Implicit dynamic relaxation:  implicit preload and explicit all in one.

ls971d   i=spinup.bar.impl_dr.k
 

3.  Two step analysis.

Preload by implicit...

ls971d i=spinup.bar.impl.k

... followed by explicit (initialized via dynain)...

ls971d  i=spinup.bar.afterimpl.k    g=d3expl




Another example of a single, pitched blade which includes 3rd step of implicit springback:  
http://ftp.lstc.com/anonymous/outgoing/jday/impldr_spinning_solid_blade_with_springback.k
http://ftp.lstc.com/anonymous/outgoing/jday/impldr_spinning_solid_blade_with_springback_via_switch_curve_and_ZEROVflag.k


Notes for spinning/rotating structures:  
Invoke 2nd order stress update with *control_accuracy.
For shells, use ELFORM 6 with IRNXX=-2.  Shell formulation 16 is noisy.