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A surprisingly popular blog-post written here is Exporting Stiffness Matrix from Ansys. A sensible follow up question is what can one do with the exported stiffness matrix? In a recent Xansys Forum post, a question was raised on how we can edit the stiffness matrix of a superelement and use it for our model.

An approach presented below is to first create a superelement that has the same number of DOF and nodal location that will serve as a template. An APDL script can then be written to edit the stiffness matrix entries as desired before exporting to a new superelement *.SUB file for use in future models. The self-contained script below demonstrates this.

**/prep7**

et,1, 185

mp, ex, 1, 200e3

mp, prxy, 1, 0.33

w = 0.1 ! single element (note nodal locations)

n, 1, w, -w, -w

n, 2, w, w, -w

n, 3, -w, w, -w

n, 4, -w, -w, -w

n, 5, w, -w, w

n, 6, w, w, w

n, 7, -w, w, w

n, 8, -w, -w, w

e, 1, 2, 3, 4, 5, 6, 7, 8

**/solu**

antype, substr ! analysis type: substructure

seopt, myse,1 ! saves stiffness matrix

m, all, all

**solve**

! Imports sub info into APDL-math form

*DMAT, myse, d, import, sub, myse.sub, stiff

! Export to apdl array for editing

*EXPORT, myse, apdl, apdlmat

! Make edits as desired

apdlmat(2,2) = 28 ! example edit to be checked later

! Put back to APDL-math form

*DMAT, myse, ,import, apdl, apdlmat

! exports desired sub file

*EXPORT, myse, sub,

**newse.sub**, stiff, , done**!! To verify it works as expected**

finish

/clear ! start from scratch

**/prep7**

et, 1, 50

se,

**newse****/solu**

eqslv, sparse

wrfull, 1

solve

finish

*DMAT, MatK_check, D, import, full, file.full, stiff

*EXPORT, MatK_check, apdl, apdlmat_check

shouldbe28 = apdlmat_check(2,2)

*stat, shouldbe28

**Other Resources**

Matrix Transfer between MATLAB and Ansys link

Export Stiffness Matrix from Ansys link

APDL Math Example link

Ansys's Website APDL Math Example link

Welcome to the Beginner's Guide to ANSYS at APTRON! Whether you're an engineering enthusiast, a student, or a professional seeking to enhance your skills, this guide will serve as your compass to navigate the world of ANSYS simulation software at APTRON.

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