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. _______________________________________________________ Files in http://ftp.lstc.com/anonymous/outgoing/support/FAQ_kw/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/support/FAQ_kw/impldr_spinning_solid_blade_with_springback.k http://ftp.lstc.com/anonymous/outgoing/support/FAQ_kw/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.