Retesting 3D Viscoelastic Fluid Dampers After 36 Years of Storage

A first‐generation three‐dimensional (3D) viscoelastic fluid damper (VED) consists of a cylindrical piston immersed in a vessel containing a highly viscous fluid. It dissipates energy through shearing, tensile, and compressive deformations of the fluid as the piston moves in the horizontal and vertical directions. To characterize the dynamic response of the damper for vibration and seismic isolation applications, four 3D VEDs and their fluids were tested in 1989. The same four VEDs were disassembled and retested in 2025 after 36 years of storage in a basement. Rheological testing of the fluids and mechanical testing of the VEDs, conducted using the 1989 protocols, revealed no meaningful change in either the fluid properties or the force‐displacement hysteretic response. These findings demonstrate the long‐term stability of this VED and fluid, supporting its use for vibration and seismic isolation.