multi-variate mode indicator function MMIF

Definition

measure of the phase purity of the measured mode shapes using a multiple reference

Notes

  • NOTE 1 The MMIF is given as a frequency dependent eigenvalue problem: where: [A] = [B] = is the real part of the FRF is the imaginary part of the FRF is the force eigenvector is the mass matrix l is an eigenvalue.
  • NOTE 2 The MMIF comprises the eigenvalues resulting from the solution of the eigenvalue problem for each frequency
  • NOTE 3 MMIF = 0 indicates a perfectly excited mode shape
  • NOTE 4 MMIF >> 0 indicates either no resonances in the frequency range or inappropriately excited modes.
  • NOTE 5 The MMIF yields a set of exciter force patterns that can best excite the real normal modes. It is therefore a simple but effective method to check the adequacy of the selected exciter locations.
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