$ Simple Example to illustrate use of ridgyro alter
$ Free Vibrations without Rotation
$
$ =============================================================
$
sol 103
diag 8
cend
$
title=ridgyro Example
subtitle=Free Vibrations without Rotation
echo=sort
$
disp=all
method=10
$
begin bulk
$
param, grdpnt, 0
$
eigrl, 10,,, 5
$
$include 'model.bdf'
$
$ The model consists of a shaft of length 1m which is rigidly 
$ supported at both ends. In the middle of the shaft there
$ is a rigid rotor.
$
$
$         z ^   
$           |           III Rotor
$                       III/
$           |           III           |
$           |-------------------------|  --> x
$           |1     2    I3I    4     5|
$                       III
$                       III
$
$ Problem Data:
$
$    Shaft:   Circular Cross Section with a radius of 0.01m
$             Material is steel with a Young's modulus
$             of 2.E11N/m and a mass density of 7850kg/m^3.
$
$    Rotor:   Mass:  m  =10kg
$             Polar Moment of Inertia: 
$                    Ixx=200kgm^2
$             Diametral Moments of Inertia:
$                    Iyy=Izz=100kgm^2
$
$ Units: N, kg, m
$
$ =============================================================
$
$ Data of the Shaft
$
grid, 1,,  0., 0., 0.,, 123456
=,   *4,, *1.,==
grid, 2,, 0.25
=,   *1,, *0.25,==
=(1)
$
cbeam, 1, 1, 1, 2, 0., 1.
=,    *1, =, *1, *1, ==
=(2)
$
pbeaml, 1, 1,, rod
      , 0.01
mat1, 1, 2.E11,, 0.1, 7850.
$
$ Data of the Rotor
$
conm2, 100, 3,, 10.,
     , 200.,, 100.,,, 100.
enddata