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Quasi-zero-stiffness (QZS) isolation systems have demonstrated good performance in low-frequency vibration isolation fields. However, the existing QZS isolation systems with traditional negative stiffness elements cannot support high payloads under miniaturization and simplification. To give some beneficial insights into high loading capacity, optimized structure, and good vibration isolation performance, a novel axially magnetized negative stiffness module (MNSM) is proposed based on the concepts of modularity and expansibility. Concretely, an axially magnetized negative stiffness unit (MNSU) is designed as the fundamental building block of MNSM, and the proposed MNSM can be composed of different axially magnetized negative stiffness units (MNSUs) for diversified requirements. To effectively investigate the characteristics of the MNSU, a computationally high efficient equivalent surface current method is developed. As a result, two types of MNSUs with optimized parameters are achieved, and their design procedures are presented respectively. To verify the benefits of the MNSMs, the designed QZS isolator is theoretically modeled and solved with the average method and then verified through the Runge–Kutta method. Through analyzing the isolation systems with MNSMs under different nonlinearities and dynamic parameters, the results indicate that the proposed MNSMs can endow the QZS vibration isolator with a lower resonant frequency, a wider isolation frequency range, and a smaller transmissibility. Additionally, it is also demonstrated that there is an inverse relationship between the complexity of the MNSM structure and the sensitivity of the isolation system.

The purpose of this study is to characterize the microstructure, composition, optical properties and residual stress of YbF3 films. The films were deposited by ion-assisted deposition at different ion energy. The SEM images showed that the surface of the film was uniform and smooth. The XRD patterns showed that the YbF3 films presented an amorphous microstructure. XPS measurement revealed that the ratio of F and Yb reduced with increasing ion energy. The optical constants of the films were determined from the whole optical spectrum. The refractive index increased with the ion energy. Due to the decrease in the amount of F, non-stoichiometric films were formed, and the visible light absorption of the films increased with increasing ion energy. Higher ion energy could increase the packing density, resulting in a decrease in the moisture absorption of the film. The films exhibited tensile stress. The value of residual stress increased with increasing ion energy, since moisture adsorption had an important effect on the residual stress.