I used the EXTSEOUT (ASMBULK EXTID = 15 DMIGPCH) to extract mass, stiffness and viscous damping matrices as pch file. The pch file contains KAAX and MAAX entries showing elements of stiffness and mass matrices, but there is no BAAX for damping.
I used the EXTSEOUT (ASMBULK EXTID = 15 DMIGPCH) to extract mass, stiffness and viscous damping matrices as pch file. The pch file contains KAAX and MAAX entries showing elements of stiffness and mass matrices, but there is no BAAX for damping.
OK- but you don't have any viscous dampers in the sample you sent, so I assumed you wanted modal damping. If you are just looking for the physical viscous damping, then see the attached sample (which doesn't need PARAM,SESDAMP), which indeed exports all three matrices for all the grids... I added a CBUSH element with some viscous damping. Look past the K4AAX matrix for the BAAX.
Hello, In this sample you have considered a value of 10 for physical viscous damping between grids 5 and 6 as an input. Why would it be 10? It is not possible to extract the matrix based on material properties of the model?
I am going to get physical K, M and C matrices that are n by n ( n is the number is nodes) and multiply them by mode shape matrix to get modal K,M and C matrices that are m by m (m is number of mode shapes). So another solution is to extract modal matrices directly.
I made up the value of 10... it would be whatever you know it should be... a viscous damper is something the user adds because they know they want/need it.
When you say the matrix based on material properties, I am assuming you mean the damping matrix, since that is what this thread was regarding... and yes, the material based damping (by defining GE on the material entries) can be extracted- that is what you have been seeing in the pch file as K4AAX... this is NOT viscous damping, but structural damping.
Also, the size of the matrices would be n*6, as there are 6 DOF for each node...
