To examine the coupling effects of different vibrational modes, which test is used?

• A. Two-Dimensional Test of Rigid Model with Spring Support
• B. Three-Dimensional Global Model Test
• C. Full-Scale Wind Tunnel Test
• D. One-Dimensional Beam Test

Answer: (B)

Studying how different vibrational modes influence each other requires a full three-dimensional representation of the structure to capture all possible mode interactions. A three-dimensional global model test provides geometry, materials, and boundary conditions in 3D, so bending in multiple directions, torsion, and their interactions can be excited and observed together. This lets you see how energy transfers between modes and how coupling alters the overall response, especially under realistic loading and damping.

In contrast, a one-dimensional beam test limits motion to a single plane or mode, so it cannot reveal cross-mode coupling. A two-dimensional rigid model with springs simplifies the system and misses out-of-plane and torsional interactions. A full-scale wind tunnel test focuses on aeroelastic effects and wind-structure interactions, which can complicate interpretation of intrinsic structural mode coupling. Therefore, the three-dimensional global model test is the best choice for examining coupling effects of different vibrational modes.