Design and test of a quasi-zero stiffness metastructure based on the preshaped beams for low-frequency vibration isolation
Zhimin Zhang, Qi Zhao, Diankun Pan
Abstract
• The QZS characteristics of the proposed structure are achieved using monolithic preshaped beams with cosine-shaped segments for snap-through behavior and arc segments as elastic boundaries. • The QZS characteristics depend on the matching between the arc segment and the cosine-shaped segment, and can be adjusted by the total span length of the curved beam and the apex height of the cosine-shaped segment. • The proposed QZS metastructure in the isolator exhibits better performance in isolating low-frequency vibrations compared to the nonlinear counterpart. • The proposed QZS metastructure has a programmable feature by altering the number of units and beams to achieve multi-step vibration isolation ability. The present study introduces a novel QZS metastructure, which is based on monolithic preshaped beams that draw inspiration from the snap-through behavior of cosine beams. The QZS feature is achieved by incorporating an additional arc segment, which serves as an elastic boundary, extending from the end of the cosine beam to the rigid walls. The matching mechanism between the arc segment and the cosine-shaped segment is analyzed through a static mechanical parametric analysis using the finite element method, while metastructures fabricated using 3D printing techniques are employed to experimentally validate the conceptual design. The relationships between the QZS features and the design parameters are established through a parametric analysis. A QZS isolator consisting of metastructures is designed, and its dynamic performances are verified by the experimental tests and an analytical model. The QZS isolator demonstrated a 70% reduction in peak transmissibility and a 25% lower beginning frequency of vibration compared to the nonlinear isolator lacking the QZS feature, highlighting the advantageous low-frequency vibration isolation capability of the QZS isolator. Moreover, the proposed QZS metastructure demonstrates a programmable capability by adjusting the number of units and beams. This programmable feature enables multi-step vibration isolation, which has been experimentally validated.