Input file for free vibration of rock mass

[WANGJIANHUI]

Dear users：
         I encountered a problem in the free vibration of rock mass. The operation stopped midway and the output file showed "No non-zero terms in mass matrix: Check density value for materials". I use a simple 8-node, 6-tetrahedron element. Please check my input file and point out my errors. Thank you very much.

If you are still free, I hope you can tell me how to set the tolerance and the number of eigenvalues in the input file.

[Prof. S. Govindjee]

Your node numbering does not follow the ordering rules that FEAP uses.  Please see the manual for the orientation rules that we use.  Notwithstanding, FEAP will fix the ordering for you if you issue the CHECk command before your MASS command.

One other comment.  You are using 3D solid elements, so there are only 3 degrees of freedom per node, not 6.

[Prof. S. Govindjee]

FYI, see figure 3.4(a).  In particular,  if you use a "right-hand rule" with respect to nodes 1-2-3, then your thumb should point to node 4.

[WANGJIANHUI]

Thank you for your reply. I understand, and I will modify it