LMS Test.Lab Stepped Sine Testing provides a multiple input stepped sine excitation to measure multiple input and output frequency response functions to be used for modal analysis.
By exciting the structure with a stepped sine, LMS Test.Lab MIMO Stepped Sine Testing combines the high signal-to-noise ratio of sine excitation and front-end controlled input force and provides proper excitation on lightly damped structures. During MIMO stepped sine testing, multiple sine sweeps with different phase conditions between the averages present correct frequency response functions. Accurate sine extraction results in leakage-free response spectra, while a system identification step prior to the stepped sine helps control excitation levels and increase the dynamic range of the 24-bit A/D converters. Harmonic distortion spectra and excitation level control following a reference profile provide insights into the structure’s nonlinear behavior.
Up to 16 exciters with different level control types are available. Fixed voltage level on exciters can be used for nonlinearity characterization under open loop conditions. Amplitude and phase control of input forces provide high accuracy in phase control closed loop during the stepping phase by a special MIMO FRF based control algorithm, using singular value decomposition for the FRF matrix inversions. Each control/exciter level can be set at a fixed amplitude, or according to a tabulated reference spectrum.
Frequency ranges are either linear or exponentially incremented. Multiple frequency ranges provide fine frequency resolution around resonances where necessary, and coarse resolution elsewhere to save time. These ranges can be concatenated to obtain concatenated response spectra.
LMS Test.Lab MIMO Stepped Sine Testing can be combined with LMS Test.Lab Operational Deflection Shapes and Time Animation, LMS Test.Lab Modal Analysis or LMS Test.Lab Geometry for faster data interpretation and analysis. The applications are available as stand-alone analysis environments or as add-ins to LMS Test.Lab MIMO Stepped Sine Testing.
