How to extract global mass matrix from system?

- August 3, 2021 at 11:11 pm
  
  JHPontes
  Subscriber
  
  Hello all,
  
  I am trying to obtain global mass matrix to compare with theoretical cases.
  The command I use is:
  *DMAT,MatMg,D,IMPORT,FULL,file.full,MASS
  *PRINT,MatMg,Mg.matrix
  
  However the matrix obtained is 138x138 and my model has only 3 nodes and 3 elements, thus expecting a 18x18 matrix.
  t1.txt
- August 9, 2021 at 7:31 pm
  
  dlooman
  Ansys Employee
  
  Perhaps you had an old file.full file in the directory and printed the wrong one. Your material properties are input with undefined parameters and you don't indicate what type of analysis you did. You need to do a modal analysis to get a mass matrix. Probably also better to use shared memory parallel and not distributed.
  For such a small model it might be better to create a superelement out of the model and use SELIST to output the mass matrix.
- August 11, 2021 at 6:37 pm
  
  JHPontes
  Subscriber
  
  The script I uploaded is only piece of my actual code.
  The analysis I am trying to perform is a full transient simulation. I don not understand why it would be necessary to perform a modal analysis, if transient simulation basic solves equation above, which is mass dependent.
  
  Anyway, I am not being able to extract global mass matrix and I really need this information.
  I am sending the full script to see if there is any error.