Design and performance analysis of a spiral configuration rotating mass and magnetic-mechanical coupling mechanism low-frequency vibration isolator

In this study, a nonlinear vibration isolator integrating a truss-magnetic-spring structure with additional rotational inertia mechanism (TMS-RIM) is proposed. The core configuration comprises a spiral truss spring, a repulsive permanent magnet array, and an additional rotational inertia (RIM). Static analysis reveals that the system achieves quasi-zero-stiffness (QZS) characteristics through precise matching between the negative stiffness of the permanent magnets and the positive stiffness of the truss spring. The QZS state can be achieved under different working conditions by adjusting the spacing between the permanent magnets. In the dynamic modeling, the coupling effect between the TMS-based QZS subsystem and the rotational inertial mass is comprehensively considered, and the nonlinear dynamic equations of the system are established. The displacement transmissibility is analytically derived using the harmonic balance method and numerically validated via the fourth-order Runge-Kutta (RK4) method. Parametric studies demonstrated the effective vibration isolation performance of the proposed TMS-RIM. Comparative results indicate that the TMS-RIM isolator can produce a lower resonance frequency and broader isolation bandwidth. An experimental prototype has been fabricated, and the test results verify the theoretical analysis. This study proposes a novel approach to enhance low-frequency vibration isolation via a rotational-inertial coupling mechanism.