Determination of vibration amplitudes from binary phase patterns obtained by phase-shifting time-averaged speckle...

Area of Science:

• Optical Metrology
• Mechanical Engineering
• Non-Destructive Testing

Background:

• Speckle shearing interferometry (shearography) is a valuable full-field strain measurement technique.
• Traditional time-averaging shearography in vibration analysis suffers from lower contrast and resolution, especially in industrial environments.
• Noisy fringe patterns in industrial settings pose challenges for accurate vibration analysis.

Purpose of the Study:

• To develop and validate a processing method for estimating vibration amplitude using shearography.
• To improve the identification of vibration modes for non-experts.
• To enhance the performance of shearography in industrial conditions with noisy data.

Main Methods:

• A novel method combining time-averaging and phase-shifting shearography techniques was employed.
• The method generates binary phase patterns with improved contrast and resolution over traditional time-averaging.
• Processing steps included denoising, binarization, automated nodal line detection, and amplitude assignment, followed by spatial integration.

Main Results:

• The proposed method demonstrated good performance in estimating vibration amplitude and identifying vibration modes.
• Analysis on synthetic and experimental data showed robustness against varying noise levels and fringe densities.
• Results from data acquired in an industrial environment confirmed the method's effectiveness.

Conclusions:

• The developed processing method significantly enhances vibration analysis using shearography, particularly in challenging industrial settings.
• The technique facilitates easier identification of vibration modes, making it accessible to non-experts.
• This advancement offers a more reliable and practical approach to industrial vibration testing.