Identification of Dynamic Properties of a Fixed-Supported T-Frame Using Experimental Modal Analysis

Abstract

This study comparatively investigated the dynamic properties of a fixed-supported T-frame using narrowband and broadband excitation in experimental modal analysis. The aim was to identify vibration modes and assess consistency in modal parameter extraction. Three significant modes (0-500 Hz) were precisely determined for natural frequencies, damping ratios, and mode shapes. Findings showed excellent agreement in natural frequency identification across both methods (differences < 0.15 Hz) and high mode shape correlation via the Modal Assurance Criterion. However, damping ratio estimations revealed notable discrepancies, especially for the first mode, where broadband excitation yielded significantly higher values. This highlights that the excitation method critically influences damping estimations, particularly for lower-frequency modes. In conclusion, while both methods effectively identify natural frequencies and mode shapes, this analysis underscores the sensitivity of damping ratio estimations to the selected excitation approach. The research offers insights into each technique's advantages and limitations in characterizing T-frame dynamic behavior, emphasizing careful interpretation of damping values in experimental modal analysis.

Keywords

• experimental modal analysis
• modal parameters
• frame structures
• narrowband
• broadband

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