Element stiffness matrix

[emre.biyikli]

Hi,

I have the following question: Where can I find a piece of code or clear explanation of how to calculate element stiffness matrix of a 10 noded curved surface tetrahedron? The element is SOLID187 in ANSYS.
I need this because I am calling ANSYS for an optimization problem, and I need to calculate the element stiffness matrix in MATLAB for the optimization algorithm.
I searched the web and literature extensively but did not cross something useful yet.

Thanks,

[mahmoud.alfouneh]

hi mate
in post process section, use from this short code. however you should aware that you must write file.emat previously.
1- at solution section after applying all loads and boundary conditions, write this:
EMATWRITE,YES
2. in post processing part every where(better the last lines) use this code:
*DO,i,1,NEL,1
*DMAT,matrixk,D, IMPORT, EMAT, file.emat,STIFF,i
*PRINT,matrixk,Kname.txt
*ENDDO
probably you need element mass matrix so use this:
*DO,i,1,NEL,1
*DMAT,matrixm,D, IMPORT, EMAT, file.emat,MASS,i
*PRINT,matrixm,Mname.txt
*ENDDO
NEL is number of elements and matrixk and matrixm are the name of your element stiffness and mass matrices. after crating these matrices you need to use textscan command in matlab to extraxt values
good luck and don't hesitate to contact me if you have problems
_________________
Mahmoud Alfouneh
PhD student. Sydney University