A Novel Approach for 3D-Structural Identification through Video Recording: Magnified Tracking.

Area of Science:

• Engineering
• Computer Vision
• Structural Health Monitoring

Background:

• Optical imaging and computer vision enable novel non-contact diagnostic techniques for engineering systems.
• Conventional methods for measuring structural vibrations are limited by cabling and low-amplitude responses.

Purpose of the Study:

• To propose and validate a novel framework, Magnified Tracking (MT), for non-contact measurement of low-amplitude structural vibrations.
• To overcome limitations in detecting imperceptible structural responses using conventional methods.

Main Methods:

• Synergistic use of phase-based motion magnification (PBMM) to amplify video motion and particle tracking velocimetry (PTV) for motion tracking.
• Experimental validation using a shear frame, comparing MT with conventional sensors in 2D and 3D configurations.

Main Results:

• PTV effectively measures perceptible motion, while MT, using PBMM, amplifies imperceptible responses around resonant frequencies.
• Operational deflection shapes, previously intractable, were revealed through amplified motion.
• Modal results extracted from magnified videos demonstrated MT's viability for 3D modal identification.

Conclusions:

• Magnified Tracking (MT) is a viable non-contact alternative for 3D modal identification.
• The method provides spatially dense measurements, overcoming limitations of conventional techniques for low-amplitude structural responses.