Abstract
A novel shock absorber with the preload structure and global negative stiffness is proposed for the shock isolation of sensitive systems. The novel shock absorber is composed of a linear spring and permanent magnet sets. The preload force and negative stiffness region are related to the attractive force between permanent magnet sets. The aim of this paper is to investigate the shock isolation performance of the novel shock absorber. Firstly, a static analysis of the novel shock absorber is carried out. Secondly, the motion stability of the NSA is analyzed by the Jacobian Matrix and the shock response is calculated numerically compared with the conventional preload structures. Finally, the shock test of the novel shock absorber is completed to verify the above results. It is found that the novel shock absorber could be advantageous in improving shock isolation in terms of relative displacement and absolute acceleration compared with conventional preload structures.
Highlights
A preload structure could improve the robustness of the initial equilibrium position and protect equipment from severe shock excitations
Shock and Vibration force response would not exceed the preload force with the deformation increasing due to global negative stiffness. e aim of this paper is to study the shock isolation performance of the NSA
Permanent magnet sets (1–2) and (2–1) are separated when mass moves up as shown in Figure 1(c). e relative displacement x is equal to y subtract z. e gap h between the separated permanent magnets is equal to |x|. e Vakoun studied the force between the cylindrical permanent magnets and derived the relevant calculation formula and experimental verification [10]. e attractive force between two magnet sets is the red dash-dot line shown in Figure 2, and it can be written as [10]
Summary
A preload structure could improve the robustness of the initial equilibrium position and protect equipment from severe shock excitations. It comprises a mass (5), supported by a linear spring (6) k, guiding rod (8), and four permanent magnet sets (1–1), (1–2), (2–1), and (3–1). It reveals that there are a negative stiffness region and a positive stiffness region in the force-displacement curve of the NSA. Μ e above relationship gives the value of the dimensionless equivalent force or stiffness of the NSA as a function of the preload amplitude A , the relative displacement μ, and the fitting parameter μ. It can be found that the stiffness of the NSA is negative around the equilibrium position and it decreases with the A or μ increasing
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