Potential of Non-Contact Dynamic Response Measurements for Predicting Small Size or Hidden Damages in Highly Damped...

Area of Science:

• Engineering
• Materials Science
• Non-destructive Testing

Background:

• Vibration-based structural health monitoring (SHM) is critical for assessing structural integrity.
• Traditional contact sensors for SHM face limitations in accessibility and coverage.
• High-speed camera-based measurements offer a promising non-contact alternative for SHM.

Purpose of the Study:

• To investigate the impact of camera settings (speed and resolution) on the accuracy of dynamic response measurements for crack detection in damped cantilever beams.
• To determine optimal camera parameters for precise measurement of vibration characteristics influenced by structural damage.
• To establish a relationship between crack depth, beam thickness, and damping ratio for effective damage quantification.

Main Methods:

• Experiments were conducted on 3D-printed Acrylonitrile Butadiene Styrene (ABS) cantilever beams with varying crack depths.
• The Canny edge detection technique and Fast Fourier Transform were employed to analyze vibration data captured by high-speed cameras.
• Camera settings, including resolution and frame rate, were systematically varied to assess their influence on measurement accuracy.

Main Results:

• An optimal combination of camera resolution and frame rate was identified for accurate dynamic response capture.
• Empirical models achieved over 98% accuracy in predicting natural frequency and around 90% in predicting resonance amplitude.
• The optimal frame rate was determined to be 2.4 times the beam's natural frequency for accurate measurements.

Conclusions:

• Camera settings significantly influence the accuracy of vibration-based SHM for crack detection.
• High-speed imaging provides a viable method for non-contact damage assessment in structures.
• The study establishes a framework for relating crack characteristics and damping to measurable vibration parameters.