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

Local impedance variations in structural waveguides partially reflect and absorb incidentflexural waves, motivating wave-based strategies for passive vibration control. This studydevelops and experimentally validates a wave-energy framework to quantify and optimizeflexural wave absorption by Kelvin–Voigt attachments on a finite Timoshenko beam.A finite element model is validated against Scanning Laser Doppler Vibrometry measurementsfrom a clamped–clamped aluminum beam with a passive damper mounted nearone end, with dashpot parameters identified through two independent approaches andthe discrepancies attributed to parameter uncertainty. Wave decomposition of the simulatedand measured velocity fields yields the power reflection coefficient ρ(ω) and powerabsorption coefficient α(ω) over the 0–15.3 kHz band. The spring stiffness and dampingcoefficient exhibit frequency-dependent optima and act as complementary, jointly tuned designvariables. Expressing dashpot location in wavelength-normalized coordinates revealsa recurring spatial pattern in which absorption minima cluster around half-wavelengthmultiples, while multiple spanwise positions yield near-peak absorption at any givenfrequency. This pattern is governed primarily by the flexural wavelength, decouplingplacement from parameter tuning, and persists across clamped–clamped, clamped–free,and free–free boundary conditions. Two independently tuned dampers further broaden theeffective absorption band by suppressing local minima in α(ω). These results demonstratethat measurement-driven wave decomposition provides compact, physically groundedguidelines for passive damper placement in beam structures.