Dual Configuration Vibration Damping Using a Viscoelastic Epoxy Adhesive: Experimental Characterization and Analytical Modeling

ABSTRACT This study presents a comprehensive experimental and theoretical investigation of epoxy‐based viscoelastic adhesive for structural vibration damping, evaluated through both free layer damping (FLD) and constrained layer damping (CLD) configurations. The material's mechanical and interfacial properties were characterized through tensile testing and adhesion strength measurements, while its viscoelastic behavior was assessed using dynamic mechanical analysis (DMA). Time–temperature superposition was employed to construct master curves representing the damping behavior over several decades. Differential scanning calorimetry (DSC) confirmed a glass transition temperature near 25°C for the epoxy thermoset. Vibration damping performance was experimentally evaluated using the Oberst beam method, applying FLD and CLD treatments to steel beams with varying damping layer thicknesses. The material demonstrated a peak loss factor (tan δ) of 0.95 near 32°C and maintained values above 0.3 across the 10 to 1000 Hz frequency range. System loss factors (SLFs) of 0.12 for the FLD configuration (6 mm) and 0.15 for the CLD configuration (3 mm) were achieved through modal testing. Theoretical predictions using the Ross–Kerwin–Ungar (RKU) model showed good agreement with experimental results at lower frequencies (up to ~1000 Hz), with deviations at higher frequencies due to real‐world interface and geometric effects.