Measuring the Vibration Response of Plane Panels under Stationary and Transient Mechanical Excitations using Deflectometry

Deflectometry is a full-field optical technique that allows direct measurement of the slope fields on thin and plane structures submitted to static or time-varying loadings using a high-speed camera. The local slopes are derived from simple geometrical considerations and other relevant quantities such as deflections, curvatures and strains are then easily obtained.Compared to scanning laser vibrometry, commonly used to perform contactless vibration measurements, one key advantage gained with deflectometry is that the slopes at all measurement points are obtained simultaneously so that no scan operation is required. This has two major practical implications: measurement time is greatly reduced and non-stationary excitations can be studied.This communication will recall the main principles of the deflectometry technique and its experimental setup. Deflection measurement results on a plane panel will be presented under stationary (shaker) and transient (impact hammer) mechanical excitations. Application of deflectometry data to the identification of external forces or structural parameters will also be discussed.