Topic
Modal testing
About: Modal testing is a research topic. Over the lifetime, 4047 publications have been published within this topic receiving 64772 citations.
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TL;DR: In this paper, an algorithm is proposed that efficiently estimates the covariances on modal parameters obtained from this multi-setup subspace identification, which merges the data from different setups prior to the identification step, taking the possibly different ambient excitation characteristics between the measurements into account.
91 citations
TL;DR: In this paper, an innovative sensitivity-based technique was introduced for the normalisation of operational mode shapes purely on a basis of output-only data The technique is based on the use of a controlled mass modification experiment and does not involve any analytical models Moreover, it allows to extend the applicability of many modal analysis based applications towards the domain of in-operation modal testing
91 citations
01 Jan 2003
TL;DR: In this article, the scaling factor is estimated from relative large frequency shifts without introducing any approximation errors, and the error sources are studied and a new formula introducing less approximation errors on the scaling factors is proposed.
Abstract: In this paper some further work is done following the idea introduced by Parloo et all [2] where they proposed that the scaling factor should be estimated by repeated testing introducing mass changes in different points on the structure. In this paper the approximate formula for determination of the scaling factor based on the frequency shift when introducing mass changes on the structure is derived directly from the governing equation of motion. Further the error sources are studied and a new formula introducing less approximation errors on the scaling factor is proposed. Using this new formula scaling factors can be estimated from relative large frequency shifts without introducing any approximation errors. Further it is explained how testing should be performed in order to significantly reduce approximation errors due to mode shape changes and random errors due to uncertainty on the mode shape values. It turns out that if the mass changes are well distributed over the structure, then both random errors and the approximation errors will be minimized.
90 citations
TL;DR: In this paper, a simply supported RC slab was constructed and used as a proof-of-concept example, where the temperatures at different points of the slab were recorded continuously in one day, together with a series of forced modal testing to extract its modal properties.
90 citations
TL;DR: The modal confidence factor (MCF) as discussed by the authors is a number calculated for every identified mode for a structure under test, which varies from 0.00 for a distorted nonlinear, or noise mode to 100.0 for a pure structural mode.
Abstract: The modal confidence factor (MCF) is a number calculated for every identified mode for a structure under test. The MCF varies from 0.00 for a distorted nonlinear, or noise mode to 100.0 for a pure structural mode. The theory of the MCF is based on the correlation that exists between the modal deflection at a certain station and the modal deflection at the same station delayed in time. The theory and application of the MCF are illustrated by two experiments. The first experiment deals with simulated responses from a two-degree-of-freedom system with 20%, 40%, and 100% noise added. The second experiment was run on a generalized payload model. The free decay response from the payload model contained 22% noise.
89 citations