I'm preparing a reduced model of my FEM for a Coupled load analysis (CLA). I need to deliver the following matrices:
KXX - stiffness matrix
MXX - mass matrix
AC01 - acceleration OTM matrix
DP01 - displacement OTM matrix
LTM - load OTM matrix
I'm using Femap with Simcenter Nastran as a solver. I know how to get all the matrices via CB reduction. Problem is that I need to manually modify the OTM matrices to get rid of the rotational DOFs because the CLA authority has a limited number of restitutions. I found Python libraries to read the .OP4 format from Nastran which help me to access the individual OTM matrices. I know that the rows of the OTM matrices correspond to the individual DOFs of the restitutions and that the columns are the modes/IF DOFs. This leads me to believe that I could just delete the rows corresponding to the rotational DOFs and that's it but if I run the assembled FEM with the SE then all the restitutions disappear.
Anybody here familiar with modifying the OTM matrices that could provide some guidance?
KXX - stiffness matrix
MXX - mass matrix
AC01 - acceleration OTM matrix
DP01 - displacement OTM matrix
LTM - load OTM matrix
I'm using Femap with Simcenter Nastran as a solver. I know how to get all the matrices via CB reduction. Problem is that I need to manually modify the OTM matrices to get rid of the rotational DOFs because the CLA authority has a limited number of restitutions. I found Python libraries to read the .OP4 format from Nastran which help me to access the individual OTM matrices. I know that the rows of the OTM matrices correspond to the individual DOFs of the restitutions and that the columns are the modes/IF DOFs. This leads me to believe that I could just delete the rows corresponding to the rotational DOFs and that's it but if I run the assembled FEM with the SE then all the restitutions disappear.
Anybody here familiar with modifying the OTM matrices that could provide some guidance?