How can I determine the overall stiffness matrix for a structure using Ansys?

[Mohamed_Wael]

Hi,
I know that Ansys APDL can determine the stiffness matrix for any structure, I would like to know if I can determine the overall stiffness for this structure or not if yes how can I do this? thanks.

 

[Mech_Engineer]

The stiffness matrix is the overall stiffness for the structure, it is the stiffness in every direction for the structure for any arbitrary loading and boundary condition. To find the stiffness for a particular set of conditions, you need to apply boundary conditions to the model.

This paper has a useful overview on slides 22-32: http://www.engr.uvic.ca/~mech410/lectures/FEA_Theory.pdf

 

[Mohamed_Wael]

Thanks a lot for your help.
Let me clarify my question, I can use ansys to extract the stiffness matrix for a structure using this procedure

I want to find stiffness and mass matrix from ANSYS Classic. I found a method from internet. It is as follows.
1.Build your model normally. No need to apply boundary conditions
2. solu->New analysis->Substructuring
3.Sol->Analysis options and give your substructure name
4.solu->Master DOFs->Define->Pick All->All DOF->OK
5.solu->solve LS
6. Click UM->List->Other->Superelement Data Set the name of your *.sub file, the name you defined in step 3, and set KOPT=Full Contents, then click OK
7.ANSYS will list super element data. Scroll down to:GLOBAL DOF SET NODES, LABELS=.Next ANSYS lists the order of the DOF vector for your global stiffness matrix.I have tried it and it works pretty good but now I want to get the overall/lumped/equivalent stiffness matrix for the structure like the one we get from the energy methods but using ansys. Do u know how ?