Vision-Based Measurement System for Structural Vibration Monitoring and Damage Detection

Abstract

A vision-based measurement system for vibration monitoring was proposed by using a non-projection fringe pattern. The designed artificial fringe pattern was similar to the interferogram of 2D-OCVT system, which was named as quasi-interferogram fringe pattern (QIFP) and pasted on the surface of a vibrating structure. A high-speed CMOS camera worked as a detector was used to capture the image sequence of the fringe pattern during the structural vibration. The period density of the imaged QIFP changes due to the structural vibration, from which the vibration information of the structure could be obtained. The change of the dynamics parameters of a cracked structure was analyzed by Finite Element Method (FEM), traditional accelerometer-based method and the proposed method using a roving auxiliary mass, from which the frequency shift curves can be obtained. The crack position information can be achieved confidently from the discontinuity of the frequency shift curves owing to the auxiliary mass effect when the mass was located at the crack position. The results demonstrated that the proposed method was an effective and accurate technique to measure structural vibration without introducing extra mass on the tested structure. Significant advantages of the proposed method making the measurement system suitable for vibration monitoring of engineering structures and damage detection of beam structures.