Programmable quasi-zero stiffness triaxial low-frequency isolator empowered by inverse design of Fourier-series beams and metastructure customization

Abstract

In modern precision manufacturing and metrology systems, low-frequency vibration isolation is a critical component. Compared to linear isolators, quasi-zero stiffness (QZS) nonlinear isolators offer the advantages of high static stiffness and low dynamic stiffness. In this study, a metastructure-based triaxial low-frequency isolator is developed based on the QZS principle. Specifically, an intuitively interpretable Fourier-series (FS) curved beam is first proposed as a monolithic QZS compliant mechanism. Importantly, a deep learning (DL)-based inverse design method is introduced to directly map the desired force-displacement responses to structural design parameters, enabling rapid design of QZS FS beams. Next, building blocks A and B are then designed based on the inverse-designed QZS FS beam to create metastructure unit cells. Two orthogonally stacked unit cells constitute the minimal configuration of the QZS triaxial isolator. A static model of the FS beam and a dynamic model of the isolator are developed to investigate the QZS features and vibration isolation performance. The triaxial metastructure isolator achieves QZS programmability and high integration while retaining the advantages of miniaturization and compactness. Finally, an isolator prototype through QZS programming (FS beam tailoring and unit cell matrix arrangement) is fabricated for triaxial vibration isolation testing. The results show that the proposed QZS triaxial isolator exhibits effective isolation performance against low-frequency disturbances along the $x$-, $y$-, and $z$- axes.