{"id":279779,"date":"2023-04-17T12:26:35","date_gmt":"2023-04-17T12:26:35","guid":{"rendered":"\/forum\/?post_type=topic&p=279779"},"modified":"2023-04-19T17:08:51","modified_gmt":"2023-04-19T17:08:51","slug":"apdl-real-constant-defined-in-a-table-for-static-analysis","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/apdl-real-constant-defined-in-a-table-for-static-analysis\/","title":{"rendered":"APDL: real constant defined in a table for static analysis"},"content":{"rendered":"

I would like to perform multiple static analyses changing the stiffness properties of a spring (COMBIN14). According to its documentation, the stiffnesses can be given in a table, setting TIME as the primary variable. But I cannot get the solution to consider all stiffness values in a single session.<\/p>\n

Following is a minimum example that does not work, only showing the solution for the first value of the table. It isn’t clear in the documentation how to change the TIME for linear static analyses. I tried changing the TIME manually in a *DO-*ENDDO loop, but that either doesn’t work or shows a warning message about non-standard use, which according to the COMBIN14 documentation, should be standard.<\/p>\n

\n
Edit 1: added missing Dirichlet boundary condition to spring nodes. The results still only show one solution (one set, one TIME, one LOAD STEP…), that for a zero stiffness spring.<\/div>\n
 <\/div>\n
Edit 2: Fixed code. It should work now, as expected.<\/div>\n
 <\/div>\n
FINI<\/div>\n
\/CLEAR<\/div>\n
\/FILNAME, mwe<\/div>\n
\/TITLE, mwe<\/div>\n
 <\/div>\n
\/PREP7<\/div>\n
! element types<\/div>\n
ET, 1, PLANE42,,1,2   ! simple elastic plane strain<\/div>\n
 <\/div>\n
ET, 2, COMBIN14,,2    ! spring in Y direction<\/div>\n
 <\/div>\n
! properties <\/div>\n
MP, EX, 1, 200E6<\/div>\n
MP, PRXY, 1, 0.29<\/div>\n
 <\/div>\n
max_stiff = 10**9  ! maximum spring stiffness<\/div>\n
 <\/div>\n
n_stiff = 5  ! number of stiffness increments<\/div>\n
 <\/div>\n
! table of stiffness values<\/div>\n
*DIM, k_tab, TABLE, n_stiff, , , TIME<\/div>\n
k_tab(0,1) = 1   ! zero-th row, first column<\/div>\n
*VFILL, k_tab(1,0), RAMP, 1, 1  ! zero-th column, 1 to n_stiff<\/div>\n
*DO, i, 2, n_stiff, 1<\/div>\n
    k_tab(i) = 10**(LOG10(max_stiff)*i\/n_stiff)<\/div>\n
*ENDDO<\/div>\n
 <\/div>\n
! real constants for COMBIN14 using k_tab<\/div>\n
R, 1, %k_tab%  ! I don’t know how to use this<\/div>\n
 <\/div>\n
! mesh<\/div>\n
N, 1, 0.0, 0.0<\/div>\n
N, 2, 0.1, 0.0<\/div>\n
N, 3, 0.0, 0.1<\/div>\n
N, 4, 0.1, 0.1<\/div>\n
 <\/div>\n
N, 5, 0.0, 0.2<\/div>\n
N, 6, 0.1, 0.2<\/div>\n
 <\/div>\n
TYPE, 1<\/div>\n
E, 1, 2, 4, 3<\/div>\n
 <\/div>\n
TYPE, 2<\/div>\n
REAL, 1<\/div>\n
E, 3, 5<\/div>\n
E, 4, 6<\/div>\n
 <\/div>\n
FINI<\/div>\n
 <\/div>\n
\/SOLU<\/div>\n
 <\/div>\n
SELTOL, 1E-15<\/div>\n
 <\/div>\n
NSEL, S, LOC, Y, 0<\/div>\n
D, ALL, ALL, 0<\/div>\n
ALLSEL<\/div>\n
 <\/div>\n
! Edit 1: forgot to clamp upper spring nodes<\/div>\n
NSEL, S, LOC, Y, 0.2
D, ALL, ALL, 0
ALLSEL<\/div>\n
 <\/div>\n
NSEL, S, LOC, X, 0.1<\/div>\n
NSEL, R, LOC, Y, 0.1<\/div>\n
F, ALL, FX, 1000<\/div>\n
F, ALL, FY, 1000<\/div>\n
 <\/div>\n
ALLSEL<\/div>\n
 <\/div>\n
ANTYPE, STATIC, NEW<\/div>\n
EQSLV, SPAR, 0,<\/div>\n
 <\/div>\n
!SOLVE  ! this was here previously to edit 2<\/div>\n
 <\/div>\n
! Edit 2: now working as intended<\/div>\n
NROPT, FULL  ! THIS IS THE MISSING PIECE<\/div>\n
TM_START = 1               ! start time
TM_END = n_stiff           ! ending time
TM_INCR = 1                ! time increment
*DO, TM, TM_START, TM_END, TM_INCR
    TIME, TM  ! set time
    SOLVE
*ENDDO<\/div>\n
 <\/div>\n
FINI<\/div>\n
 <\/div>\n
\/POST1<\/div>\n
SET, FIRST<\/div>\n
ESEL, S, TYPE, , 1<\/div>\n
\/EFACET, 1<\/div>\n
PLNSOL, U, SUM, 2, 1.0<\/div>\n
\/CONTOUR,1,64,AUTO,,<\/div>\n
\/REPLOT<\/div>\n<\/div>\n

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