Origami-inspired Isolators with Quasi-Zero Stiffness for Coupled Axial-Torsional Vibration

Vibration isolators with quasi-zero stiffness (QZS) property is an ideal solution for suppressing undesirable vibrations in engineering systems. Previous QZS isolators were mainly designed based on single-degree-of-freedom QZS structures without the capability for multi-directional vibration isolation. In this work, a Kresling-origami-inspired isolator (KOI) with QZS property in axial, torsional and coupled vibration is proposed. The KOI consists of two symmetric Kresling origami elements (KOEs), while a KOE is assembled by a base and an axial spring in parallel. Based on the static analysis, the bi-stability of bases is designed to provide negative stiffness. The QZS property of KOE is achieved by utilizing the special point Case-Q, which provides a novel strategy to design such an isolator. Such QZS property is only available for the KOE under axial or torsional excitation, while the KOI is further extended for isolating coupled excitations. The dynamic responses of KOI are calculated by solving its governing equations. Comparison between the theory results and those simulated in ADAMS shows good agreement. The transmissibility of the proposed isolator under axial and torsional vibration excitations is demonstrated to be able to achieve efficient vibration isolation performance, even full frequency range of vibration isolation for relatively weak excitations due to its nonlinearity. The developed theoretical framework and findings will provide a new way to design effective QZS isolators for multi-directional vibrations.