An application of operational modal analysis in modal filtering

Abstract

Modal filtration in the field of damage detection has many advantages, including: its autonomous operation (without the interaction of qualified staff), low computational cost and low sensitivity to changes in external conditions. However, the main drawback of this group of damage detection methods is its limited applicability to operational data. In this paper a method of modal filter formulation from the in-operational data is described. The basis for this approach is FRFs synthesis using knowledge of the operational modal model. For that purpose a method of operational mode shape scaling is described. This is based on the measurements of several FRFs of the object. The method is then applied to the construction of modal filters and modal filtration. Additionally, the study presents verification of the method using data obtained from simulation and laboratory experiments. Verification consisted of comparing the results of modal filtering based on classical experimental modal analysis with the results of the approach proposed in the work.