*Heading
 Substructure with CPE3 Elements
*Node
      1,          -1.,           1.
      2,          -1.,          0.5
      3,          -1.,           0.
      4,          -1.,         -0.5
      5,          -1.,          -1.
      6,         -0.5,           1.
      7,         -0.5,          0.5
      8,         -0.5,           0.
      9,         -0.5,         -0.5
     10,         -0.5,          -1.
     11,           0.,           1.
     12,           0.,          0.5
     13,           0.,           0.
     14,           0.,         -0.5
     15,           0.,          -1.
     16,          0.5,           1.
     17,          0.5,          0.5
     18,          0.5,           0.
     19,          0.5,         -0.5
     20,          0.5,          -1.
     21,           1.,           1.
     22,           1.,          0.5
     23,           1.,           0.
     24,           1.,         -0.5
     25,           1.,          -1.
*Element, type=CPE4, elset=one
 1,  1,  2,  7,  6
 2,  2,  3,  8,  7
 3,  3,  4,  9,  8
 4,  4,  5, 10,  9
 5,  6,  7, 12, 11
 6,  7,  8, 13, 12
 7,  8,  9, 14, 13
 8,  9, 10, 15, 14
 9, 11, 12, 17, 16
10, 12, 13, 18, 17
11, 13, 14, 19, 18
12, 14, 15, 20, 19
13, 16, 17, 22, 21
14, 17, 18, 23, 22
15, 18, 19, 24, 23
16, 19, 20, 25, 24
** Region: (Secn:Picked)
*Elset, elset=I1, generate
  1,  16,   1
** Section: Secn
*Solid Section, elset=I1, material=Elas
1.,
**Nset, nset=Set4,
** 25,
**Nset, nset=Low_Left
** 5,
** 
** MATERIALS
** 
*Material, name=Elas
*Density
10.,
*Elastic
 1e+08,0.
*step
*frequency,eigen=lanc
2,
*boundary
1,1,2
5,1,2
21,1,2
25,1,2
*node print 
u,
*end step
*STEP
*substructure generate, type=z1, overwrite, 
recovery matrix=yes, mass matrix=yes,
libr=lib_rbm_solid2d
*RETAINED NODAL DOFS
**,sorted=no
1,1,2
5,1,2
21,1,2
25,1,2
**1003,1,2
*SELECT EIGENMODES
1,2
*substructure matrix output, stiffness=yes, 
mass=yes, recovery=yes, file=lib_rbm_solid2d
*END STEP