Experimental Investigations on Mechanical Properties and Cantilever Structure Vibration Mitigation Performance of a Rotationally Tunable Permanent Magnet MR Damper

Cantilever structures in civil engineering are prone to undesirable vibrations induced by dynamic loads such as wind, seismic forces, and operational excitations, threatening structural safety and serviceability. Among vibration control technologies, magnetorheological (MR) dampers are promising for such structures due to their rapid response and continuous damping tunability. Traditional coil-driven MR dampers, however, suffer from high energy consumption and heat accumulation, limiting their long-term application. To address these issues, this study proposes a novel rotationally tunable permanent magnet-based MR damper featuring radially magnetized permanent magnets and a rotational adjustment mechanism. The structural design of the damper is elaborated, with key parameters optimized via COMSOL finite element simulation. Mechanical property tests were conducted under various frequencies, amplitudes, and adjustment angles, verifying the damper’s continuous tunability of damping force (2300–3800[Formula: see text]N). Vibration mitigation performance experiments on a cantilever structure (free vibration, harmonic excitation, and white noise excitation) demonstrate that the proposed MR damper reduces cantilever tip displacement by up to 90% and peak acceleration by 75% under operational loads. The proposed low-energy, durable permanent magnet MR damper provides an effective vibration control solution for civil engineering cantilever structures, enhancing their resilience in harsh environments and high-precision operational contexts.