*HEADING
 EIGENVALUE ANALYSIS OF AN UNCONSTRAINED 1-ELEMENT MESH  [COH3D8]
*PREPRINT, MODEL=YES
*NODE,NSET=ALL
 1, 0., 0., 0.
 2, 0., 0., 10.
 3, 10., 0., 10.
 4, 10., 0., 0.
 5, 0., 10., 0.
 6, 0., 10., 10.
 7, 10., 10., 10.
 8, 10., 10., 0.
*ELEMENT,TYPE=COH3D8,ELSET=EALL
 1, 1, 2, 3, 4, 5, 6, 7, 8
*COHESIVE SECTION, MATERIAL=COH, ELSET=EALL, RESPONSE=TRACTION SEPARATION, THICKNESS=GEOMETRY
*MATERIAL,NAME=COH
*ELASTIC, TYPE=TRACTION
  2.0E11, 1.0E11, 1.0E11
*DENSITY
 7800., 
*STEP
*FREQUENCY, EIGENSOLVER=LANCZOS, SIM=NO
24, , ,-1.E6 
*END STEP