Full field modal measurement with a single standard camera

The full field measurement of 8 vibration modes of a cantilever plate, up to the kHz frequency is performed using a single standard camera. The image acquisition is carried out at low rate but using fast exposure time (1/4000 s) that “freezes” a part of the motion. A deflectometry setup coupled with digital image correlation analysis allows angle fields, then deflection fields, to be measured. An out-of-plane displacement database is generated from all stored fields. This snapshot library is finally post-processed using principal component analysis techniques and adapted weights that enable space vibration fields to be extracted. A test case is performed on a reflecting cantilever steel plate. 370 deflection fields are measured allowing 8 space vibration fields to be extracted. The natural frequencies of those modes are estimated using the Rayleigh ratio. A coarse and visual comparison with a numerical simulation shows similar results for 6 of the 8 space modes.