Tips & Tricks

Difference in radiation efficiency in SEA vs. hybrid models with DAF excitation

I see a difference in radiation efficiency in my SEA vs. hybrid models with DAF excitation - why? The SEA radiation efficiency is the efficiency of the resonant modes. The FE radiation efficiency is the efficiency of the response.

Getting negative TI from periodic module

what can be the reason of getting a negative TI from periodic module? Its likely caused by a too coarse mesh

How do I re-scale my node coordinates?

One should be able to copy the nodes (including the node numbers) into Excel or equivalent, re-scale there, and then paste with override back in VA One. Alternatively, one can use the following script, where the scaling factor is set. /* Script to factor coordinated for all nodes. The scaling factor is hard coded in scaling_factor

Does the FE face mesh density influence the computation time of the FE area junction?

The FE face mesh density of an FE area junction does not influence the computation time to the same extent, in a pure FE structure/FE acoustic problem,

Calculate Hybrid TL

How does VA One calculate hybrid TL? Hybrid transmission loss is calculated from the transmission coefficient, given by τ12 = 16 pi / A k12 Sumrs [Im{Ddir(2)}rs (Dtot,s-1 Im{Ddir(1)} Dtot,s-H)rs ]

What to consider when projecting TBL data?

Best is to use data in the correct/local plane, so no projection is needed. This will also not introduce approximations regarding the actual flow. However if projection is needed the wave number and decay coefficients should be projected

Amplitudes are incorrect when importing external modes

When importing external modes, the amplitudes are incorrect - what can be the cause?

Radiation Efficiency from HAJ is dependent on loading - is that expected?

This is expected, as the Radiation efficiency will depend on which modes you excite. From help: "For an FE subsystem the radiation efficiency indicates the in-situ radiation efficiency (rather than the radiation efficiency of the resonant modes of the panel). The radiation efficiency of a structural FE subsystem depends on its response (i.e. depends on the loading, damping, coupled subsystems, etc...)."

Using results from the periodic subsystems module in my SEA model

Where do I use results from the periodic subsystems module in my SEA model?

Does using imported NASTRAN damping matrices add much to the solve time?

Import may take some extra time, but this should not be significant. Also, the fully populated damping matrix shouldn't make much difference in the solution time as we don’t use a sparse matrix for the modal matrix. As soon as you have hybrid or many different things that matrix gets fully populated anyway