Absorption Characteristics of a Passive Damper-Augmented Timoshenko Beam Using a Wave-Decomposition Approach

Local impedance variations in structural waveguides partially reflect and absorb incident flexural waves, motivating wave-based strategies for passive vibration control. This study develops and experimentally validates a wave-energy framework to quantify and optimize flexural wave absorption by Kelvin-Voigt attachments on a finite Timoshenko beam. A finite element model is validated against Scanning Laser Doppler Vibrometry measurements from a clamped-clamped aluminum beam with a passive damper mounted near one end, with dashpot parameters identified through two independent approaches and the discrepancies attributed to parameter uncertainty. Wave decomposition of the simulated and measured velocity fields yields the power reflection coefficient ρ(ω) and power absorption coefficient α(ω) over the 0-15.3 kHz band. The spring stiffness and damping coefficient exhibit frequency-dependent optima and act as complementary, jointly tuned design variables. Expressing dashpot location in wavelength-normalized coordinates reveals a recurring spatial pattern in which absorption minima cluster around half-wavelength multiples, while multiple spanwise positions yield near-peak absorption at any given frequency. This pattern is governed primarily by the flexural wavelength, decoupling placement from parameter tuning, and persists across clamped-clamped, clamped-free, and free-free boundary conditions. Two independently tuned dampers further broaden the effective absorption band by suppressing local minima in α(ω). These results demonstrate that measurement-driven wave decomposition provides compact, physically grounded guidelines for passive damper placement in beam structures.