Research On Fatigue Life Design Of U-shaped Bellows Based On Valve Seal

Valve seals are widely used in aerospace,nuclear industry,petrochemical industry and other industries due to their excellent sealing performance,low friction loss and long service life.As an important component of the valve seal,the bellows is the main cause of fatigue failure of the valve seal.Therefore,it is very important to ensure that the fatigue life of the bellows meets the requirements of use.The traditional physical experiment to ensure the fatigue life index of the bellows requires multiple physical experiments,which have many disadvantages such as long research and development cycle and high funding.This paper explores the effect of structural parameters wave height,wave distance,and wall thickness on the stiffness,stability,and fatigue life of small-diameter U-shaped bellows for valve sealing through CAE software ABAQUS and FE-SAFE,and explores an orthogonal experiment through design A new method for designing the structural parameters of U-shaped bellows combined with finite element simulation.Through the calculation and analysis of the elastoplastic finite element model of the U-shaped bellows used for valve sealing,it is found that the fatigue failure of the bellows is caused by the accumulation of plastic strain.The peaks and troughs of the bellows are the dangerous locations for fatigue failure.Comparing the results of the elastoplastic finite element model with the pure elastic model and the theoretical calculation formula,it is found that the finite element simulation method is more reliable in calculating and analyzing the performance of the bellows,and the elastoplastic finite element model is more accurate than the pure elastic model.Using the control variable method to analyze the performance changes of the bellows under different structural parameters,it is found that the structural parameters are changed by changing the stiffness of the bellows.The change of the stiffness changes the stress generated by the bellows under the same load,which affects the bellows Fatigue life.At the same time,the analysis and calculation results show that the change of wave height and wall thickness can affect the stiffness of the bellows more than the wave distance.The effect of wave height,wave distance and wall thickness on the stiffness of the bellows is consistent with the rule of the stability of the bellows.The law of fatigue life is reversed.Starting with the wave height,wave distance,and wall thickness of the structural parameters of the bellows,an orthogonal experimental scheme is designed,and the performance index of each scheme is calculated using the method of finite element simulation.Through the analysis of the results of the orthogonal experiment,comprehensive consideration of various factors,the combination of structural factors with performance indicators that meet the design requirements is obtained.The results prove that this new method of design optimization of the structural parameters of small-diameter U-shaped bellows is feasible and can effectively improve the design and development efficiency of new products.