Hello everyone,Abaqus 

I am new to FEM and Abaqus. In the dat file of steady state dynamics analysis, the data shows two rows for each node. One row contains acceleration values and directly below it, there's another row marked "SSD" that contains all zeros. What is the difference between these 2 rows?

Contents of .dat file:

INCREMENT NUMBER     1
                             FREQUENCY =   10.000000    
                                      N O D E   O U T P U T
  THE FOLLOWING TABLE IS PRINTED FOR NODES BELONGING TO NODE SET ASSEMBLY_PART1
 
      NODE FOOT-  A1             A2             A3             AR1            AR2            AR3          
           NOTE
 
        1      0.0000000E+00  1.6883751E-04  0.0000000E+00  0.0000000E+00  0.0000000E+00  3.3791830E-04 
        1 SSD  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00 
        2     -3.0956130E-05  1.6597480E-04  0.0000000E+00  0.0000000E+00  0.0000000E+00  3.3799017E-04 
        2 SSD  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00 
        3     -6.0862517E-05  1.5748483E-04  0.0000000E+00  0.0000000E+00  0.0000000E+00  3.3790952E-04 
        3 SSD  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00  0.0000000E+00