Abstract:

To break the limitations of the multi-dimensional (M-D) vibration isolation (VI) platforms with the Stewart-Gough design, such as strongly coupling motions, excessive friction in connections, heavy weight, and limited workspace, this study processes a novel platform integrated by a stiffness-adjustable origami spring sub-structure and a parallel mechanism. The origami-based stiffness-adjustable spring realizes low-frequency VI, and the parallel mechanism symmetry design realizes motions decoupling. In the origami-based sub-leg, the parallel-stack-assembly (PSA) design mechanism with two Miura origami configurations is proposed to generate a symmetrical negative stiffness property. Paired with a linear positive stiffness spring, the origami-based sub-leg has wide-amplitude-high-static-low-dynamic stiffness (WA-HSLDS) characteristics in one direction. Then, with construction of the parallel mechanism connected with origami-based sub-legs, an M-D VI platform is achieved, whose motions in the vertical direction and yaw direction are decoupled with the motions in the other directions. Based on the dynamic model and incremental harmonic balance (IHB) with the arc-length continuation method, appropriate structural parameters in the parallel mechanism part are figured out, and the accurate transmissibility in different directions is defined, which gives the parametric influencing investigations for realization of low-frequency VI performances. Finally, experiments are conducted to validate the accuracy and feasibility of the theoretical methods, and to demonstrate the performance of M-D low-frequency isolation with load-carrying capacity of the proposed VI platform. The integration of the origami into the parallel mechanism results in a compact, efficient, and flexible platform with nonlinear adjustability, offering new possibilities for lightweight M-D VI, and developing the practical applications in high-precision platforms in ocean and aerospace environments.

Key words: multi-dimensional (M-D) vibration isolation (VI), wide-amplitude high-static-low-dynamic stiffness (WA-HSLDS), origami-based elastic spring, parallel mechanism