Variance computation of the Modal Assurance Criterion

Szymon Gres (1) , Michael Dohler (2) , Palle Andersen (3) , Laurent Mevel (2)

1 AAU - Aalborg University [Denmark]
2 I4S - Statistical Inference for Structural Health Monitoring
3 SVIBS - Structural Vibration Solutions

Modal validation is an integral part of any modal analysis scheme. Recent advances in efficient variance computation of modal parameter estimates from the output-only subspace-based identification algorithms made the computation of variance feasible for the modal parameters, such as natural frequencies, damping ratios and mode shapes. One of the other practical modal indicators is Modal Assurance Criterion (MAC), for which uncertainty computation scheme is missing. This paper builds on the previous results using the propagation of the measurement uncertainties to estimates of MAC. The sensitivity of the MAC with respect to output covariances is derived using a first order perturbations and the uncertainties are propagated using the Delta method. The influence of the underlying mode shape scaling on both the uncertainty of mode shapes and MAC is investigated. The results are presented in context of operational modal analysis (OMA) of a spring mass system.

Mots clés: OMA; OPERATIONAL MODAL ANALYSIS

Mots clés: ALGORITHME; ANALYSE MODALE

Domaines: Dynamique, vibrations; Applications [stat.AP]

Szymon Gres, Michael Dohler, Palle Andersen, Laurent Mevel. Variance computation of the Modal Assurance Criterion. ISMA 2018, 28th Conference on Noise and Vibration Engineering, Sep 2018, Leuven, Belgium. 12 p. ⟨hal-01886642⟩