Inverse-designed metastructures with customizable low dynamic stiffness characteristics for low-frequency vibration isolation

The quasi-zero stiffness (QZS) vibration isolator is considered to be an effective way to address the contradiction between high load-bearing capacity and low-frequency vibration isolation. However, the design of traditional QZS isolators with multiple components, brings about complexity in structure integration, while designing a structure that is compact and lightweight is required for many engineering applications, especially for aerospace engineering. In this study, inverse design was employed to achieve QZS characteristics of the curved beam system. The trajectory of the cross-section center of a curved beam was optimized by using the genetic algorithm. The present design strategy has the advantage of achieving customizable stiffness and load-bearing capability, as well as constructing multiple QZS regions. The harmonic balance method was employed to analyze the dynamic response of the metatructure, and a parameter analysis was conducted to assess its isolation performance. Numerical simulations were also used to validate the theoretical model in the time and frequency domains, respectively. It is demonstrated by experiment that the proposed metastructure can effectively isolate vibrations above 4.67 Hz, with a mass of only 3.2% of the its load-bearing capacity. The presented design strategy provides a feasible solution for the compact and lightweight low-frequency vibration isolators, particularly benefiting miniature devices, precision instruments, and aerospace applications where space and weight constraints are critical.