Crystal Instruments EDM Modal Standard, Advanced & Premium Modal Analysis

The Modal Analysis module picks up the FRF data produced by modal testing. Through Modal Data Selection, FRF signals are organized for rapid, comprehensive review, one by one or together in one graph, and can be exported or imported from other sources, with individual FRFs added or replaced. Identification starts with one click: Mode Indicator Functions (MIF, in Multivariate, Complex, Real and Imaginary Sum forms) help label natural frequencies and reveal repeated and closely spaced roots. A Stability Diagram combined with curve fitting then selects the physical poles, mode shapes are computed and stored in a shape table, and results are validated with the MAC function and FRF synthesis.

The tiers build on each other. Standard implements the proven Least-Square Complex Exponential (LSCE) fitter for pole identification and the Least-Square Frequency Domain (LSFD) algorithm for mode shapes, plus signal smoothing with deconvolution (for OMA), a user-selectable identification band, mode shape animation (wireframe, surface contour, FFD, interpolation, node lines, an animation equation editor for unmeasured DOFs) and synthesized-versus-measured FRF comparison with correlation and error values. Advanced adds the Poly-Reference Time Domain (PTD) method to curve-fit the FRF matrix from MIMO results on top of all Standard features; the fitter is selected automatically per single or multiple reference.

Premium adds Poly-X, the poly-reference Least-Square Complex Frequency Domain (p-LSCF) algorithm for MIMO FRF matrices, giving a neat stability diagram that emphasizes stable poles; time-domain, Poly-X or SSI methods can all be chosen for single- or poly-reference data sets. A dedicated Operational Modal curve fitter brings in Stochastic Subspace Identification (SSI), cleaner and more efficient for operational modal analysis on single- or multi-reference cross-power spectrum data.