An origami-inspired low-frequency isolator with one/two-stage quasi-zero stiffness characteristics

As an emerging technology, Kresling origami exhibits rich nonlinear mechanical and kinematic properties. However, previous studies have tended to focus on one of these properties, and few have utilized its kinematic properties to design specifical mechanical properties. Inspired by the axis-rotation coupling property of Kresling origami, a novel composite anti-vibration structure (CAS) utilizing an improved cam-roller mechanism is proposed for flexible low-frequency vibration isolation. The mountain creases are simulated by rigid rods, while the valley creases are neglected to enhance the axis-rotation coupling effect as much as possible. Unlike conventional cam-roller mechanisms, the improved cam-roller mechanism overcomes the cam size limitation on working stroke and avoids friction damping of the sliding rods. By setting different cam profiles, one/two-stage quasi-zero stiffness (QZS) characteristics with wide QZS ranges can be achieved, thus enabling passive variable loading of CAS. Considering the nonlinear inertia induced by the rotating platform, the dynamic equations of CAS are established using Lagrange principle. And the Alternating frequency–time harmonic balance method is used to solve the equations, which avoids the fitting error caused by Taylor's formula. The effects of nonlinear inertia, equilibrium position, excitation amplitude, and damping on vibration isolation performance of the CAS are analyzed. It is found that changes in excitation amplitude and equilibrium position affect both nonlinear stiffness and inertia, thus affecting vibration isolation performance. Comparative discussions demonstrate CAS has wider QZS ranges and weaker stiffness nonlinearity than typical QZS isolators, X-shaped isolators, and linear isolators, which leads to superior low-frequency vibration isolation at large excitations. Both static and dynamic experiments verify the accuracy of the theoretical analysis, confirming wide QZS range and excellent low-frequency vibration isolation performance of CAS. This work presents a simple, feasible low-frequency vibration isolation scheme that may promote practical engineering applications of origami and cam-roller structures.