Study On Vibration Isolation Characteristics Of Metal Bellows

The metal bellows is a class of the cylindrical thin-walled elastic shell, laterallywith corrugated, play the role of vibration and noise reduction in piping systems. Inthe actual working conditions, in order to improve damping effect of metal bellows,need to study the vibration isolation characteristics of metal bellows.Based on the DN219type metal bellows for the object, this article adopts themethod of combining the simulation and test is studied. By using ANSYS finiteelement software to establish model of metal bellows, study on the effect of geometricparameters, structural configurations and damping material properties about dampingeffect of metal bellows, finally, through experiments to verify the model. Simulationresults show that: when the excitation frequency is40Hz, the damping effect of metalbellows increases with increasing wave height and wave number, decreases withincreasing wave distance, wall-thickness, diameter and modulus of damping materials,first increases then decreases with increasing thickness of damping material; When theexcitation frequency is13.5Hz, the damping effect of metal bellows first decreasesthen increases with increasing wave height, wave distance, wall-thickness, diameter,wave number and modulus of damping materials. More complex relationship betweenthe damping effect of metal bellows and thickness of damping material, when thethickness of the damping material is less than0.1mm, decreases with increasingthickness of damping material，the thickness of damping material is greater than0.1mm and less than0.2mm, increases with increasing thickness of damping material,the thickness of damping material is greater than0.2mm and less than0.3mm,decreases with increasing thickness of damping material, the thickness of dampingmaterial is greater than0.3mm, increases with increasing thickness of dampingmaterial; When the excitation frequency is5Hz, the damping effect of metal bellowsdecreases with increasing wave height and wave number, increases with increasing wave distance, wall-thickness, diameter and modulus of damping materials, firstdecreases then increases with increasing thickness of damping material.Then Studying on vibration test about DN219type metal bellows, by comparingthe results of the test with the results of finite element analysis, find that error onallowable range, Can satisfy the requirement of engineering practice, also verify thecorrectness of the model, provide some reference value for the future design of themetal bellows.During the experimental study of DN550type metal bellows, With the negativepulse and hammering method respectively do free vibration experiment for metalbellows without damping, compare the two excitation effect, though hammeringmethod experiment is convenient and spend less, but its energy is limited and not easyto control, this method can be used for lightweight structural system, but does notapply to large high stiffness of metal bellows; The negative pulse method can be morestable input impact energy, concerning resonance frequency can fully stimulate. Whenjoining damping materials between layer and layer, dynamic stiffness and dampingcoefficients decrease, This is mainly due to the friction damping between the layers ofmetal bellows is greater than damping of viscous materials; Test also show thatinterlayer viscous damping material can effectively attenuate high frequency vibration.