{"id":250837,"date":"2023-02-21T16:56:59","date_gmt":"2023-02-21T16:56:59","guid":{"rendered":"\/forum\/forums\/topic\/export-prestressed-stiffness-matrix-of-a-sector-model-with-cyclic-symmetry\/"},"modified":"2023-02-21T16:56:59","modified_gmt":"2023-02-21T16:56:59","slug":"export-prestressed-stiffness-matrix-of-a-sector-model-with-cyclic-symmetry","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/export-prestressed-stiffness-matrix-of-a-sector-model-with-cyclic-symmetry\/","title":{"rendered":"Export prestressed stiffness matrix of a sector model with cyclic symmetry"},"content":{"rendered":"

Hi everyone,<\/p>\n

I’ve got a problem with exporting the prestressed stiffness matrix of a sector model with cyclic symmetry. I’m looking for the way of recovering the condensed cyclic interface DOFs in the global stiffness matrix.<\/p>\n

 <\/p>\n

For a non-prestress sector model, I managed to export its full stiffness\/mass matrix by running a modal analysis for the FREE<\/strong> model without constrained DOFs and cyclic interfaces and then by reading the matrix from the ‘.full’ file.<\/p>\n

 <\/p>\n

           HBMAT,’Output\\K_HB_SEC.%Index_Sec%’,txt,,ASCII,STIFF,YES,YES<\/p>\n

 <\/p>\n

For the sector model in the spinning condition, I have to firstly run a cyclic static analysis with the cyclic status on and constrained DOFs in the hub<\/strong>.<\/p>\n

 \/PREP7<\/p>\n

CYCLIC<\/p>\n

\/SOLUTION<\/div>\n
ANTYPE,STATIC !STATIC ANALYSIS<\/div>\n
OMEGA,0, 0, Vel_Rot_RAD<\/div>\n
RESCONTRAL,LINEAR,ALL,1<\/div>\n
 <\/div>\n
! BOUNDARY CONSTRAINTS: selected nodes at the disk hub <\/div>\n
ALLSEL,ALL<\/div>\n
CMSEL,S,NSEL_BC,NODE<\/div>\n
D, ALL, ALL, 0 <\/div>\n
ALLSEL,ALL<\/div>\n
 <\/div>\n
SOLVE<\/div>\n
FINISH<\/div>\n
 <\/div>\n

In the subsequent modal analysis, I tried to set the cyclic status off but failed. The constraints in the hub are deleted. Then with the cyclic status on, the exported stiffness\/mass matrix only covers a part of the nodes in the sector model.<\/strong> It seems that the DOFs attached on one of the cyclic interfaces are condensed out in the global matrix. Moreover, it seems the node mapping with the exported matrice do not match the original sector model.<\/p>\n

\/SOLU<\/div>\n
ANTYPE,STATIC, RESTART, , , PERTURB<\/div>\n
PERTURB,MODAL,,,NOKEEP <\/div>\n
SOLVE, ELFORM<\/div>\n
 <\/div>\n
MODOPT,LANB,1,<\/div>\n
WRFULL,1<\/div>\n
 <\/div>\n
! DELETE ALL NODE CONSTRAINTS<\/div>\n
ALLSEL,ALL<\/div>\n
DDELE, ALL, ALL<\/div>\n
 <\/div>\n
ALLSEL,ALL<\/div>\n
SOLVE<\/div>\n
FINISH<\/div>\n
 <\/div>\n
So I’m looking for the way of exporting the full prestressed stiffness matrix with all the DOFs in the original sector model (free body) included.<\/div>\n
Any suggestions and comments will be highly appreciated.<\/div>\n
 <\/div>\n
Thanks,<\/div>\n","protected":false},"template":"","class_list":["post-250837","topic","type-topic","status-closed","hentry","topic-tag-apdl","topic-tag-cyclic-symmetry","topic-tag-prestress"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t