nastran nvh
nastran nvh
(OP)
I have already published this question in other forum. What is the best method to calculate point dynamic stiffness (mm/sec/Newton) in nastran for automotive application.
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RE: nastran nvh
If you run it in frequency domain you can get velocities as function of frequency.
Or use F = m * a. If you know the mass you can calculate the acceleration and then the speed at a given time.
Just some ideas
/Thomas
RE: nastran nvh
The other question that arise is with boundary condition, as whether to run as free free state or constrained state.
To reduce the CPU time, is it true to run the quarter body model and get the same response as with full model.
May be I am missing something out very basic here.
RE: nastran nvh
Direct means that the equations of motion are solved directly. That means that all modes are included in the calculation.
The "best" choice depends on the problem. I think you should study that a bit before making the choice but the results from both methods should be the same provided your solution parameters are correct.
As for boundary conditions, the requirement is the obvious. They should reflect the phisics/mechanics of the model. If you have double symmetri, sure use it.
Good Luck
Thomas
RE: nastran nvh
Assuming I use sol 111 approach and use free free condition.
I will need bailout card if I use unit force on RLOAD card.
Which I am not sure if its correct.
Can I use SPCD card. If I can then I would not be able to apply the unit force.
RE: nastran nvh
Basically, say that you apply you load in dof T1, you should be able to combine that with constants in T2, T3, R1, R2 and R3. This will give you a singular solution for a static load due to one rigid body motion. But sol 111 should work as far as I know. Provided I understand you correct.
I would not "play" with the bailout card for other reasons than "error detection", the limitation are there for a reason.
Good Luck
Thomas