Accurate high-speed displacement measurement method for slender structures based on the sampling moiré method

This study proposes what we believe to be a novel displacement measurement method to indirectly measure the width-direction displacement by calculating the phase difference in the length direction, which effectively solves the problem of difficulty in measuring the width-direction displacement of elongated structures. This method is implemented by fabricating an oblique 45° grating, capturing the grating image with a high-speed camera, performing the length-direction phase analysis via the sampling moiré method, and calculating the width-direction displacement ingeniously. The accuracy verification shows that this method has high displacement measurement accuracy and stability. The test part simulates the vibration process of elongated structures such as blades through a set of vibration devices, and the displacement-time curves are obtained. The results show that the method can effectively reflect the displacement change of the vibrating blade, and its frequency spectrum is further obtained by the Fourier transform. In summary, this work aims to propose a new measurement method with high accuracy, high speed, easy operation, and full-field coverage for a class of elongated structures, which has important scientific and engineering values.