I am trying to solve a basic problem. First of all, I created line body (BEAM188) which is 2 beam element 2 fixed support and the middle node have 6DOF. Afterward I got the results in ANSYS workbench.
However, I exported stiffness and mass matrix from ANSYS and import these matrices into MATLAB to calculate iegenfrequencies and I had different results than ANSYS Workbench. Moreover, the stiffness and mass matrices have totally different structure than the theoretical stiffness and mass matrices. I have zeros matrices, where they shouldn't be, accordingly to theoretical global stiffness and mass matrices.
Also, ANSYS Workbench add midside nodes automatically to use quadratic shape function which leads to more nodes at the structure (18x18 matrices instead of 6x6 matrices)
Please explain that:
**Why I have different results than ANSYS WB when I calculate the eigenfreqeuncies with ANSYS stiffness and mass matrices?
**How does ANSYS setup these matrices with midside nodes mathematically?
hi
maybe you read stiffness and mass matrices by wrong commands. try to use this code. it gives you the right mass and stiffness matrices.
/OUTPUT,cp,out,,
/debug,-1,,,1
Hi,
The size of stiffness matrix will be 18x18 for ur ANSYS model as you are having 3 nodes with 6 DOFs at each node. So use a 2D beam element without any mid side nodes to generate the standard 6x6 matrix. Also in Workbench by default the Geometric stiffness terms will be included. Try again by not considering this geometric non linearity into account.
Its not possible to turn off the midside node function of ansys for beam188 element And I am using this command to export the matrices:
! Stiffness
*DMAT,MatKD,D,IMPORT,FULL,file.full,STIFF
*PRINT,MatKD,Kdense.matrix
! Mass
*DMAT,MatMD,D,IMPORT,FULL,file.full,MASS
*PRINT,MatMD,Mdense.matrix
Hi , Oguzhan Yalcin
you call can determine matrix by code when i input this code in ansys W.B
- Badges
- Science topic