Performance of Optical Structural Vibration Monitoring Systems in Experimental Modal Analysis

Area of Science:

• Structural dynamics and experimental modal analysis.
• Optical measurement techniques and sensor technology.

Background:

• Conventional structural dynamics measurements often rely on accelerometry.
• Optical vibration monitoring systems are emerging as alternatives but lack well-defined performance metrics.
• Their application in experimental modal analysis requires thorough evaluation.

Purpose of the Study:

• To provide evidence for the capability of optical vibration monitoring systems in modal identification.
• To conduct a comparative performance analysis of different optical systems against accelerometers.
• To offer guidance for selecting and implementing optical systems for structural vibration monitoring.

Main Methods:

• A scaled 3D building frame model was used in a laboratory setting.
• Dynamic response was measured using five optical motion capture systems (laser Doppler velocimetry, fiducial markers, marker-less pattern recognition).
• Measurements were compared against data from high-precision accelerometers following impulse excitation and initial displacement.

Main Results:

• Modal parameters identified by optical systems were not always equivalent to accelerometer data.
• Each optical system exhibited limitations inherent to its specific design.
• Performance varied across different optical measurement techniques.

Conclusions:

• Optical vibration monitoring systems show potential for modal identification but require careful selection.
• Understanding system-specific limitations is crucial for accurate structural vibration monitoring.
• The study provides guidance to aid in the choice and implementation of these optical systems.