The Dynamic Performances Analysis And Structural Parameter Optimization Of S-shaped Welded Metal Bellows

In this paper the S type welded metal bellows on mechanical seal were studied.First abrief introduction to the finite element analysis method and kinetic theory. Then create a finiteelement numerical model of the number of different diaphragm and working conditions giventhe relevant boundary conditions. The deformation,stress,strain and stiffness of the numberof bellows were comprehensive comparative studied. And a numerical relationship betweenthem were established. Secondly, the axial and torsional stiffness were analysied to use oftheoretical calculations and finite element method for single, double bellows, the calculationresults were compared with validation. Finally the modal analysis and structural sizeoptimization were detailed analysis of the bellows diaphragm. So further improved theaxial deformation and stiffness of the diaphragm. A more reasonable bellows diaphragm sizewere obtained and thus a new optimization of diaphragm shape were proposed. The mainfindings are as follows:1) The stress,strain and displacement of the diaphragm on different layers bellowsthestructure of the numerical model established and contrast analysied using finite elementanalysis method. under the conditions that external force is relatively of the first diaphragmoutside(special case), from the second diaphragm, the stress and strain Had little effect onthe number of diaphragm.But the axial deformation gradually increased with the increasethe number of the diaphragm. And the increase of the external axial deformation increased tospeed up.the increase of the axial displacement had good effects for the stiffness ofbellows (decrease).2) The axial stiffness and torsional stiffness in the elastic range of single and doublebellows are got with numerical analysis and standard of EJMA method. Then the axial andtorsional stiffness are separately measured by design of special fixture and theory results arecompared with the numerical results data and analysis.Therefore the reasonable calculating method of axial stiffness and torsional stiffness for S-type single and double welded metalbellows are obtained. Verify that the bellows were essentially rigid on reverse direction. Bythe calculating the number of different diaphragm of the bellows, can be analysied thestiffness of the number of diaphragm, with the increase of the diaphragm number wereobtained the stiffness decreases and the diaphragm number20began to become stable.3) Optimize the size of the diaphragm structure, the elimination of stress concentration inthe original model. And improve the axial displacement and stiffness of the diaphragm.Launched a more reasonable size of the bellows diaphragm. And disappeared the stressconcentration after optimization to re-establish the finite element model. The number of unitsand nodes after optimize more than before. This indicates that after the optimization model ismore sophisticated discretization.4) Deformation also increased with the increase in the number of bellows diaphragm.This indicates that the axial deformation (displacement) increases, the stiffnessdecreases, thedeflection increases.