LMS Test.Lab MIMO Modal Sine Testing provides modal testing and analysis for large and complex structures where broadband excitation with sufficient energy is difficult. Typical applications include (vibro-) acoustic modal testing and analysis, (reciprocal) modal testing and analysis of trimmed car bodies or other large assemblies with high damping and low response levels. The FRFs are measured using swept sine excitation, traditional broadband or impact hammer modal testing.
The Geometry Workbook allows fast generation of wire-frame and full 3D visualization of modal testing and analysis results. TEDS makes geometry creation even faster by reading the position information from pre-programmed transducers.
Through exitation with a sweeping sine, the MIMO Modal Sine Testing combines the high signal-to-noise ratio of sine excitation with the measurement speed of broadband testing. Multiple sine sweeps with different phase conditions between the averages provide high-quality FRFs. Accurate sine extraction results in leakage-free response spectra, while a system identification step prior to the sine sweep allows to control the excitation levels and further increase the dynamic range of the 24-bit A/D converters. Harmonic distortion spectra and excitation level control following a reference profile allows to gain insights in the structure’s non-linear behaviour.
The Modal Testing Shake Workbook provides dedicated test set-ups for a multiple shaker FRF test, including excitation level balance checks and input force decorrelation validation. The Modal Testing Impact workbook provides embedded expert guidance for trigger parameter setting and FFT-window selection, with immediate feedback showing the effect of parameters changes on the last measurement. The ODS add-in provides immediate feedback to validate the correctness of FRF by animation of the geometry model.
The LMS PolyMAX parameter estimation algorithm significantly simplifies the analysis process by offering crystal-clear stabilization diagrams, thus reducing the operator-dependency of the resulting modal model, typically occurring for complex, highly damped structures.
