*KEYWORD $ From eigenvalue analysis, axial mode is mode #38 at f=9096 $*control_implicit_eigenvalue $100 $*control_implicit_general $1,1 $ stiffness damping does not damp RB motion but does damp axial mode. $ If we do an undamped analysis and do a FFT of the von Mises stress time history, $ it's clear that the frequency of oscillation is ~9200, same as the axial mode *damping_part_stiffness 1,0.10 *control_hourglass 8 *control_accuracy 1,2 $ mass damping stops rotating blade $*damping_global $,2800 *CONTROL_TIMESTEP $ .7 is ok for 10% damping $ 0.0000000 0.7000000 0 0.0000000 0.0000000 0 0 *initial_velocity_generation 1,2, 3000. 0.,0.,0.,0.,0.,1. *database_glstat 0.0001 *DATABASE_BINARY_D3PLOT 0.0000100 0 *CONTROL_TERMINATION 0.0090000 0 0.0000000 0 0.0000000 *TITLE spinning shells *MAT_ELASTIC 1 3.00000-4 1.00000+7 0.3000000 *SECTION_SHELL 1 16 0.0000000 0.0000000 0.0000000 0.0000000 0 0.1000000 0.1000000 0.1000000 0.1000000 0.0000000 *PART 1 1 1 0 0 0 0 0 *NODE 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55-1.000000000E+00 1.000000000E+00 0.000000000E+00 0 0 56-3.333333433E-01 1.000000000E+00 0.000000000E+00 0 0 57 3.333333433E-01 1.000000000E+00 0.000000000E+00 0 0 58 1.000000000E+00 1.000000000E+00 0.000000000E+00 0 0 59 1.666666627E+00 1.000000000E+00 0.000000000E+00 0 0 60 2.333333254E+00 1.000000000E+00 0.000000000E+00 0 0 61 3.000000000E+00 1.000000000E+00 0.000000000E+00 0 0 62 3.666666746E+00 1.000000000E+00 0.000000000E+00 0 0 63 4.333333492E+00 1.000000000E+00 0.000000000E+00 0 0 64 5.000000000E+00 1.000000000E+00 0.000000000E+00 0 0 *ELEMENT_SHELL 1 1 1 17 18 2 2 1 2 18 19 3 3 1 3 19 20 4 4 1 4 20 21 5 5 1 5 21 22 6 6 1 6 22 23 7 7 1 7 23 24 8 8 1 8 24 25 9 9 1 9 25 26 10 10 1 10 26 27 11 11 1 11 27 28 12 12 1 12 28 29 13 13 1 13 29 30 14 14 1 14 30 31 15 15 1 15 31 32 16 16 1 17 33 34 18 17 1 18 34 35 19 18 1 19 35 36 20 19 1 20 36 37 21 20 1 21 37 38 22 21 1 22 38 39 23 22 1 23 39 40 24 23 1 24 40 41 25 24 1 25 41 42 26 25 1 26 42 43 27 26 1 27 43 44 28 27 1 28 44 45 29 28 1 29 45 46 30 29 1 30 46 47 31 30 1 31 47 48 32 31 1 33 49 50 34 32 1 34 50 51 35 33 1 35 51 52 36 34 1 36 52 53 37 35 1 37 53 54 38 36 1 38 54 55 39 37 1 39 55 56 40 38 1 40 56 57 41 39 1 41 57 58 42 40 1 42 58 59 43 41 1 43 59 60 44 42 1 44 60 61 45 43 1 45 61 62 46 44 1 46 62 63 47 45 1 47 63 64 48 *END