研究目的
To develop a low-cost and compact single-camera stereo-DIC system for 3D full-field high-frequency vibration measurements, overcoming the Nyquist-Shannon frequency limitation using a down-sampling approach.
研究成果
The developed LSSC stereo-DIC system effectively measures 3D full-field vibrations up to 4 kHz using a low-frame-rate camera and down-sampling approach. Experimental validation on a cantilever plate and turbine blade shows good agreement with accelerometer data, with errors generally below 10%. The system is compact, low-cost, and suitable for industrial applications, though it requires further optimization for broader frequency ranges and larger areas.
研究不足
The system requires a single known frequency component for the vibration signal, limiting its application to harmonic excitations. The spatial resolution is reduced due to the use of half the camera sensor for each view. High-intensity lighting is needed to avoid image blurring, which restricts the measurement area size. The method may not be suitable for signals with multiple or unknown frequencies.
1：Experimental Design and Method Selection:
The study uses a pseudo-stereo optical setup with two planar mirrors and a single low-speed camera to create stereo images. Stereo-DIC is employed for 3D reconstruction, and a down-sampling strategy with Non-Harmonic Fourier Analysis (NHFA) is used to handle high-frequency vibrations.
2：Sample Selection and Data Sources:
A cantilever plate and a turbine blade with speckle patterns are used as targets. The cantilever plate is excited by an electrodynamic shaker, and measurements are compared with an accelerometer.
3：List of Experimental Equipment and Materials:
Equipment includes a T-REX
4：2 M camera, planar mirrors, a lens, a signal generator, a power unit, a shaker, and an accelerometer. Materials include aluminum plates, spray paint for speckle patterns, and a 3D-printed turbine blade. Experimental Procedures and Operational Workflow:
The optical system is calibrated using a chessboard pattern. Vibration tests are conducted at frequencies from 400 Hz to 4000 Hz. Images are acquired at low frame rates, processed with stereo-DIC for 3D displacement maps, and analyzed with NHFA for amplitude and phase.
5：Data Analysis Methods:
Data is analyzed using stereo-DIC algorithms for 3D reconstruction and NHFA for signal amplitude estimation. Comparisons are made with accelerometer data using Fourier analysis.
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