High-Noise High-Speed Footage Data in Experimental Modal Analysis

Vibration measurements using optical full-field systems based on high-speed footage are typically heavily burdened by noise, as the displacement amplitudes of the vibrating structures are often very small (ranging in micrometers, depending on the structure) and therefore troublesome to measure as they are close or bellow the noise level of the measurement system. This paper demonstrates the modal parameter identification on such noisy measurements. It is shown that by using state of the art identification methods (Least Squares Complex Exponential or Least Squares Complex Frequency combined with Least Squares Frequency Domain), identification is still possible. The modal parameter identification improves the quality of the measured modal data and serves as a reduced model of the structures dynamics.