Study Of Equivalent Stiffness Of The Multilayer Bellows Considering Fluid-solid Interaction

Multilayer bellows is made up of multi-layer thin shell structure, compared with the same thickness of single-layer structure, multilayer bellows has large displacement compensation and reduced capabilities of vibration and noise, and it's widely used in piping system.Stiffness is one of the main performance parameters for bellows design, the present research on stiffness mainly uses finite element, curved beam model, practical empirical formula and experimental method.This paper takes interlayer damped multilayer metal bellows as the research object, uses ADINA FEM software to analysis and study the axial equivalent stiffness of multilayer bellows. Through bellows static analysis, get axial equivalent stiffness of bellows changed from interlayer damped material characteristics and bellows parameters. Results show that, axial equivalent stiffness is increased while thickness and modulus increased of damped materials, but the rate of increase is unlikely, especially with the damping elastic modulus increased, axial equivalent stiffness increased is very small. The axial equivalent stiffness of bellows is increased while the outer diameter, wave spacing, wall thickness of bellows root increased, is decreased while wave height, wave number, of bellows root increased, is linearly increased while elastic modulus of metallic materials increased.Establishing a rational numerical simulation model of equivalent stiffness for multilayer bellows considering fluid-Solid interaction, get the water conditions impacting on the axial equivalent stiffness of bellows. Results show that, the impact of water pressure on axial equivalent stiffness of bellows is very small.Considering fluid-solid interaction, the dynamic stiffness of bellows must be reduced, and through dynamic test of multilayer bellows considering fluid-solid interaction, the finite element analysis and experimental results are consistent, the relative error of the two is small. Verifying the results of finite element analysis are valid, provides a basis for the further studying the dynamic characteristics of bellows.