Troubleshooting

Attune won’t load my SOL 103 or SOL 200 data.

  • Did you use dmap?

  • Did Nastran run successfully?

  • Did you include an output request for displacements?

Using MSC Nastran, my Nastran job fails and complains of duplicate nodes or elements, but my model doesn’t have duplicates.

  • This is a feature of MSC Nastran. When MSC Nastran runs, it creates a file with the extension IFPDAT. The existence of this file for future runs causes the job to die.

  • Try deleting any files in your working directory with the file extension IFPDAT.

  • Stop MSC Nastran from creating the IFPDAT file by setting system cell IFPSTAR=NO on the command line or in the rcf file.

Attune won’t allow me to use cross-orthogonality.

  • No mass matrix in the input file. Set PARAM,MREDUC to ASET or USET.

  • There is no intersection between the DOF of the mass matrix and the DOF for the test shapes. Is the node numbering between the test and analysis model compatible?

Attune says my correlation is horrible, but I think it’s not that bad. What’s happening?

  • Are all your units consistent across the correlation inputs?

  • Are your coordinate systems compatible?

  • Is the node numbering the same or does it need to be mapped?

  • Do you have rigid body modes included in your analysis and/or test modes? Rigid body modes are examples of very closely spaced modes (repeated roots) of the most challenging kind. The relative frequency error associated with rigid body modes could be huge because the approximation to zero in test and analysis can be off by several orders of magnitude. Also, there is no guarantee that the analysis modes spanning the rigid body space will map one-to-one onto the test-derived rigid body modes. It is only possible to require that the space spanned by the analysis rigid body modes be the same as the space spanned by the test rigid body modes.

When I ran Nastran on my updated model, the model didn’t improve like Attune said it would.

  • How large of a design change did you make in a single iteration? Attune’s predictions are based on sensitivities which are evaluated at a certain point in the design space based on linearity assumptions. The farther away from that point that you investigate in the design space, the less likely that the linearity assumptions will be accurate.

  • It’s quality, not quantity. Attune should be able to predict qualitatively how a change in design variables will result in a change of state variables. The exact change predicted is not as important.

  • The state variables as a function of design variables may be a highly nonlinear function. Sensitivities may not be capturing the complex relationship.

Attune can’t find any way to improve my design.

  • The weights on design and state variables may be interfering. Decrease the individual design weights or the overall design weight or increase the individual state variable weights.

  • The size of your design space may be too large to be reasonably searched. Eliminate design variables with low sensitivity. Make sure your design variable bounds make sense.

  • Your model may have modes with very closely spaced frequencies (repeated roots). It may be difficult for the analytical model to produce the same set of modes spanning the space of the repeated roots as was found in the test. This can be resolved by using the RSS option.

Attune won’t write out an update.

  • No design variables have changed. Attune will only update files that require changes.

Attune has disabled the design, optimization, and history buttons on the main form.

  • These buttons are not available when the active data set of the configurations is set to Pre- or Post-Optimization. All loaded configurations’ active data set must be set to Optimization and have a complete set of data for the correlation process to be available.

Attune takes a long time to load

  • Attune takes a long time to load if running from a network drive. Install on a local drive for much faster load times.

Attune can’t check out a license.

  • Is the LSHOST environment variable set?

  • Is the environment variable set correctly? You can easily check the value of the environment variable from within MATLAB by using the command: getenv(‘LSHOST’)

  • Are there tokens available for Attune?