Objectives The primary aim of this research is to develop a novel integrated adjustable magnetic constant force quasi-zero-stiffness structure. The quasi-zero-stiffness vibration isolation system has unique characteristics of high static stiffness and low dynamic stiffness, which can meet the application requirements of large load-bearing and low natural frequency simultaneously, especially suitable for vibration isolation of ship power equipment. However, traditional quasi-zero-stiffness structures generally suffer from issues such as complex structures and non-adjustable forces. Therefore, this new structure is designed to possess the magnetic constant force property and generate quasi-zero-stiffness characteristics within an ultra-long stroke range, providing a new solution for quasi-zero-stiffness vibration isolation systems.
Methods Firstly, the ANSYS Maxwell 2024 electromagnetic field low-frequency simulation software is utilized to establish a finite element model of the magnetic constant-force quasi-zero stiffness structure. This model serves as a crucial tool for simulating and analyzing the magnetic field distribution and force characteristics of the structure. Secondly, to enhance the magnetic constant-force uniformity, a parametric scanning method is employed. By varying geometric parameters such as the chamfer parameters of the inner and outer edges of the inner layer magnet, the influence of these parameters on the force uniformity is revealed. The optimal geometric dimensions are then determined through comprehensive consideration of factors like average magnetic force and force standard deviation. Subsequently, theoretical analyses of the axial magnetic force and torque around the z-axis for the constant-force structure are conducted. The theoretical expressions are derived based on the principles of magnetic interaction energy, and numerical simulations are combined to comprehensively study the magnetic force and torque generation mechanisms.
Results The results show remarkable performance of the designed structure. It can adjust the constant-force magnitude between ±683.19 N by simply rotating the outer permanent magnet. Moreover, it can generate stable magnetic constant-force over an impressive 40 mm ultra-long stroke range. The relative force standard deviation is only 4.34%, indicating excellent force uniformity. The magnetic force-displacement curves under different conditions are obtained, and the variation laws of magnetic force and torque with the axial position of the outer layer magnet and the rotation angle are clearly presented. For example, the axial magnetic force is related to parameters such as the number of pole pairs, mechanical angle, and axial position of the outer layer magnet, and the torque around the z-axis has its own unique variation characteristics.
Conclusions This new structure provides a fresh and practical approach for the development of quasi-zero stiffness vibration isolators. It overcomes some of the limitations of traditional structures and shows great potential in various fields. However, when applying it to practical ship engineering, challenges such as structural complexity, environmental durability, installation space limitations, and cost-effectiveness need to be addressed. Future research can focus on material optimization, intelligent design, and modular integration to promote the large-scale application of quasi-zero-stiffness vibration isolation technology in the ship engineering field.
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