Experimental Investigation of Suspension Cord Material Influence on Modal Parameters in Free-Free Boundary Conditions
Abstract
During the design stage of engineering structures, determining their dynamic response is essential to ensure performance and long service life. Experimental Modal Analysis (EMA) is a widely used method for this purpose, as it provides critical modal parameters (natural frequencies, damping ratios, frequency response) and reveals the dynamic behavior of structures. In the EMA, structures are typically excited at single or multiple locations, and the responses are measured using sensors under various boundary conditions. One common approach is the free-free boundary condition, which involves suspending test structures using suspension cords to simulate unconstrained behavior. This study investigates how the material of suspension cords affects the dynamic characteristics of a structure. Two cord materials—nylon and rubber—along with four different combinations of these cords were tested. Results indicate that while the natural frequencies remain unchanged (%1-%2 difference) across different suspension materials, the damping ratio is notably affected. The measured damping ratios ranged from 0.95% (nylon) to 3.45% (rubber), demonstrating the significant influence of suspension material on energy dissipation. Additionally, harmonic response measurements confirm that differences in damping ratios due to the suspension material are clearly detectable.
Keywords
Experimental Modal Analysis, Natural Frequency, Damping Ratio, Free-Free Boundary Condition
Supporting Institution
Authors gratefully thank the Scientific Research Project (BAP) Coordination Unit of Düzce University for financial support (Project number: 2021.06.05.1221).
Project Number
2021.06.05.1221
Ethical Statement
This study does not involve human or animal participants. All procedures followed scientific and ethical principles, and all referenced studies are appropriately cited.
Thanks
Authors gratefully thank the Scientific Research Project (BAP) Coordination Unit of Düzce University for financial support (Project number: 2021.06.05.1221).
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