Structural Model Tuning Tool: User's Reference Manual

This report presents an efficient approach for tuning finite element models to match the
measured ground vibration test and static test data. Frequencies, mode shapes, total weight,
location of the center of gravity, and static deformation computed from the finite element model
are matched to the measured data. The model tuning procedure used in this work is based on
solving an optimization problem in which the errors for the considered metrics, between the
finite element prediction and the measured data, are minimized. Analytical sensitivity values of
performance indices are computed using the NASTRAN-generated sensitivity values together
with the in-house computer codes, which allow for faster computational time and the use of
gradient-based optimizers. The method is applied to the Aerostructures Test Wing IV model.
The study shows that the military standard and the National Aeronautics and Space
Administration standard for comparing analytical and experimental modal data are all satisfied.
The final finite element model correlates well with the test data. The flutter speed decreases by
8.91 percent after model tuning compared with the original Aerostructures Test Wing IV design.