Design and experimental study of quasi-zero stiffness vibration isolator based on electromagnetic attraction type

This paper proposes a frictionless stiffness-adjustable magnetic suspension vibration isolator (MSVI). By utilizing the displacement of an l-shaped armature connected to the bearing platform to adjust air gap dimensions between upper and lower electromagnets, the device constructs a controllable electromagnetic force differential to generate negative stiffness characteristics, effectively resolving the long-standing technical dilemma in conventional vibration isolation systems where load-bearing capacity conflicts with isolation performance. Through an integrated methodology combining theoretical modeling, numerical simulation, and experimental validation, the research first establishes and analytically solves the system's dynamic control equations, accompanied by stability analysis and numerical verification. Parametric studies subsequently reveal the influence patterns of critical factors on isolation performance. The experimentally validated static electromagnetic force model demonstrates excellent fitting accuracy with theoretical predictions. Frequency sweep tests (0–15 Hz) on a single-layer isolation platform confirm MSVI's isolation capabilities. Results indicate that while enhancing isolation performance, the MSVI system amplifies vibration amplitudes and induces soft spring characteristics, manifesting as leftward bending of frequency response curves and unstable intervals. Experimental data show a 1.91 Hz reduction in initial isolation frequency (to 10.83 Hz) and a 43.07 % decrease in peak transmissibility (to 10.89 dB), verifying current regulation's optimization effects. This solution provides a novel technical pathway to overcome the "stability-isolation performance" trade-off in nonlinear vibration isolation systems. The established theoretical models and experimental findings hold significant engineering value for precision instrument isolation and spacecraft payload protection applications.