Determination of Natural Frequency and Damping Ratio in a Cantilever Beam System with Moving Mass Using Image Processing-Based Modal Analysis
10. BILSEL International World Science and Research Congress, İstanbul, Türkiye, 9 - 10 Mayıs 2026, ss.477-489, (Tam Metin Bildiri)
- Yayın Türü: Bildiri / Tam Metin Bildiri
- Basıldığı Şehir: İstanbul
- Basıldığı Ülke: Türkiye
- Sayfa Sayıları: ss.477-489
- Eskişehir Osmangazi Üniversitesi Adresli: Evet
Özet
In this study, it is aimed to determine the natural frequency and damping ratio of a system consisting of an elastic beam clamped to a cart moving in the horizontal direction and an eccentric mass evaluated either at a fixed position or at its post-motion position on the beam, using an image-processing-based modal analysis approach. The study focuses on the identification of an existing mechanical system and considers only the extraction of modal parameters through non-contact measurement.
In the experimental method, a high-contrast marker is tracked throughout the video frames, and the obtained time-dependent displacement data are processed through resampling, detrending, and noise reduction procedures. The dominant vibration frequency is determined using the Fast Fourier Transform. The damping ratio is calculated from the band-limited free vibration signal using the logarithmic decrement method.
Two different modal analysis conditions are investigated in this study: the first corresponds to the structural reference modal parameters obtained while the cart and the eccentric mass are held at a fixed position; the second corresponds to the effective modal parameters extracted from the residual vibration region after the trapezoidal motion of the cart is completed.
For this reason, the intrinsic damping associated solely with the beam and the effective damping are defined separately, and the physical interpretation of the modal analysis results is discussed accordingly. As a result, it is demonstrated that the image-processing-based approach provides a low-cost and practical experimental modal analysis method for determining the natural frequency and damping ratio under both stationary and post-operation conditions.
Keywords: image processing, experimental modal analysis, natural frequency, damping ratio, cantilever beam, moving mass, FFT, logarithmic decrement