Objectives This study aims to develop a novel integrated adjustable magnetic constant-force quasi-zero-stiffness (QZS) structure. The QZS vibration isolation system features high static stiffness and low dynamic stiffness, making them particularly suitable for isolating vibrations in ship power equipment, where both heavy load-bearing and low natural frequency are required. However, traditional QZS structures generally suffer from issues such as structural complexity and non-adjustable forces. The proposed structure incorporates magnetic constant-force property and achieves QZS behavior over an ultra-long stroke range, offering a new solution for advanced vibration isolation applications.
Methods Firstly, the ANSYS Maxwell 2024 electromagnetic field low-frequency simulation software was utilized to establish a finite element model of the magnetic constant-force QZS structure. This model serves as a crucial tool for simulating the magnetic field distribution and analyzing the force characteristics. Secondly, to improve the uniformity of the magnetic constant force, a parametric scanning method was employed, varying geometric parameters, including the chamfering of the inner and outer edges of the inner layer magnet. The influence of these parameters on force uniformity was analyzed, and optimal geometric dimensions were determined by balancing average magnetic force and standard deviation. Additionally, theoretical models were developed for the axial magnetic force and torque around the z-axis for the constant-force structure based on magnetic interaction energy principles. These models were validated through numerical simulations to investigate the mechanisms of magnetic force and torque generation.
Results The results show outstanding performance of the proposed structure. The magnetic constant-force magnitude can be adjusted within a range of ±683.19 N by simply rotating the outer permanent magnet. The structure maintains a stable magnetic constant-force output over an extended stroke range of 40 mm, with a relative force standard deviation of only 4.34%, indicating excellent force uniformity. The magnetic force-displacement curves under different conditions were obtained, clearly illustrating the relationships between magnetic force, torque, and the axial position and the rotation angle of the outer layer magnet. For example, the axial magnetic force is influenced by parameters such as the number of pole pairs, mechanical angle, and axial position of the outer layer magnet, while the torque around the z-axis exhibits distinctive variation behavior.
Conclusions This newly designed structure provides an innovative and practical approach for the development of QZS vibration isolators. It addresses key limitations of traditional structures and shows great potential in various fields. However, when applying it to practical marine engineering, challenges such as structural complexity, environmental durability, installation space constraints, and cost-effectiveness need to be addressed. Future research can focus on material optimization, intelligent design, and modular integration to promote the widespread adoption of QZS vibration isolation technology in ship engineering.
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