Experimental modal analysis – Algorithm

The algorithm used to calculate modes in DIRAC is based on the Principal Response Function (PRF). The PRF helps to reduce the effect of noise and to fit modes on a large number of FRFs quickly. The LSCF algorithm is used to find the poles of the system.

The algorithm implemented in DIRAC consists of 6 steps:

1. PRF application.
2. Frequency band selection.
3. Least-squares complex frequency (LSCF) pole estimation.
4. Stabilization diagram visualization.
5. Residue fit.
6. Globalization.