Discrepancy between FEM mass and mass during optimization

Greetings,

 

I have a FEM model whose mass calculated by Hypermesh (under Tools > masscalc) is equal to 2.22 kg

 

I am running a free-size optimization of this model. From the design parameters summary reflected in the *.out file (shown below), the sum of design and non-design mass is equal to 2.51524 kg:

 

After the iterations begin, the mass registered in iteration 0 is 2.34766 kg

 

Question: Is it wrong to expect the following: FEM mass = (design + non-design mass) = mass at iteration 0? Why are these values different?

 

 

 ---------------------------
   Design Parameters Summary :
   ---------------------------
   Total # of free-sizing design elements          :     34684
   Total # of free-sizing cards                    :         1

   Total Volume of Design Material :   9.3119E-05
     Total Mass of Design Material :   4.1904E-01
     Volume of Non-Design Material :   7.0062E-04
       Mass of Non-Design Material :   2.0962E+00

 

 

 

 

ITERATION   0

 *** INFORMATION # 3454
 MPC constraints for subcase 1 will be enforced
 with lagrange multipliers.

 (Scratch disk space usage for starting iteration = 65356 MB)
(Running out-of-core solution)
Objective Function (Min(Max) EQATN) =  4.50698E+07
Maximum Constraint Violation %      =  0.12535E+03
Design Volume Fraction              =  6.00000E-01   Mass     =  2.34766E+00