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2.6  ANSYS interfacing

• Non-linear springs
• Superelement generation (Craig-Bampton type)

2.6.1  Non-linear springs

For spring representations of volumes or surfaces, a first common approach is to use so called rigid elements. ANSYS supports

• CE, CERIG, MPC184, RBE 2 : rigid connections where the spring is connected to a master node with 6 DOF which enforce motion of a number of slave DOFs.
• TARGE 170+CONTA 173, TARGE 170+CONTA 174

2.6.2  Superelement generation (Craig-Bampton type)

The cards typically used for superelement generation in ANSYS are

• antype,substr specify FE substructure generation in after /SOLU
• cmsopt,fix,Nshapes,,,,,tcms card generates .sub (import with ans2sdt('read','file.sub')) and .tcms files.
• resvec,on to use residual vectors in the basis
• seopt,name,MatType,1 with MatType=2 for mass and stiffness, and 3 for stiffness, mass, viscous damping, name must be defined with card /FILENAME before the analysis.
• m,NodeId,all master DOF definition repeat card for the various interface nodes. You will have to replace all with UX,,UY,UZ,ROTX,ROTY,ROTZ if the DOF is used by an element that supports multi-physics.

/FILENAME,ubeam_se  ! name must be the one used in SeOpt command
/PREP7
!...
! Use command F to apply loads that will define the residual vector
/SOLU

antype,substr  ! substructure analysis

CmsOpt,Fix,20,,,,,TCMS
RESVEC, ON
SeOpt,ubeamse_ans,3,1,0,,  ! 3(all matrices,2 for m and k), 1 to print

! Define list of master DOF, you cannot use ALL if the elements support multi-physics
M,1,UX,,,UY,UZ,ROTX,ROTY,ROTZ
M,5,UX,,,UY,UZ,ROTX,ROTY,ROTZ
M,8,UX,,,UY,UZ,ROTX,ROTY,ROTZ
M,12,UX,,,UY,UZ,ROTX,ROTY,ROTZ

SAVE  ! save .db file
SOLVE ! generate the matrices
FINISH