Abstract: Air spring is a kind of low-frequency, high-efficiency vibration isolator. At present, it is widely used in ship main power equipment to reduce vibration and noise transmission. Whether air springs have equilibrium performance will seriously affect the vibration isolation system security and reliability, while the cord winding angle is a critical factor to determine the equilibrium performance of the air spring. To quantitatively analyze the influence of cord winding angle on the equilibrium performance of air spring, for naval JYQN air spring, the geometric model of airbag is simplified. Based on non-moment theory of elastic thin shell, airbag balance equation and boundary condition are established, then both longitude and latitude internal force formula of the airbag are derived. Furthermore, combined analysis of airbag composite material, cord equilibrium angle formula is given and analysis method of air spring equilibrium performance is proposed. When lay angle of airbag skeleton cords is close to the neutral angle, the deformation of airbag subjected to inner pressure and outer load is at a minimum, that is, it has a good equilibrium performance. Functional relationship between cord neutral angle and air spring effective area is established, which provides a theoretical basis for the design and development of air springs.

Key words: Air spring, Equilibrium performance, Neutral angle, Winding angle