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Sol 601/129 - checking external forces in f06

I am running sol 601/129 (NX9) for some impact simulation. The model has solid, shell, connection and lumped mass (CONM2) elements. Some documentation I got from GTAC on sol 601/129 a while back suggested checking the 'external forces' in the solution accuracy indicators table of the first iteration to see if BC is set up properly. Though referred to as 'force', this quantity looks like linear momentum to me because of its units. Regardless, when I check this quantity for the first iteration, it does not match with what I expect it to be based on manual calculations (see attached ppt). The initial velocity times the total FEA model mass is about twice of what I see in the f06 file. Whether it is coincidense or not, when I use the mass of the model minus the lumped mass elements, this value matches reasonably closely with the external forces value in f06. Are the CONM2 masses being used in external force calculation ? By the way, I am using 1e-6 as the shell drilling parameter DRILLKF, whether it helps this discussion or not.

 

Apart from this, the simulation results look normal to me. Results for first iteration show all nodes, including the ones with lumped masses, have the imposed velocity, have gravity as the acceleration and elements are stress free prior to impact.

 

Any comments ?

 

Thanks

 

Bulent