Analysis And Optimization Of Diaphragm Stress Of Ultrapure Water Diaphragm Valve

The ultrapure water diaphragm valve is mainly composed of a diap hragm,a valve seat and a driving mechanism.It has the characteristics of simple structure,good sealing performance,and strong corrosion r esistance.In the ultrapure media system,the ultrapure water diaphragm valve is the most commonly used valve struc ture.If the ultrapure medium is contaminated or leaked due to the rupture or failure of the diaphragm,it may affect the function of the ent ire system and even cause a safety accident,which will seriously reduce the working stability and reliability of t he ultrapure medium system,so its life span Stability has a great influence on the entire ultrapure media system.This subject uses a combination of theoretical analysis and simulation calculations to study the influence of manual adjustment and pneumatic drive on the flow and pressure of the ultrapure water diaphragm valve,and the force of the diaphragm.Multi-objective genetic algorithm is used to measure the stress of the diaphragm.The details are as follows:Firstly,the method of fluid-solid coupling and structural stress(Von Mises criterion)is used to analyze the influence of manual adjustment and pneumatic driving on the flow state and pressure during the opening and closing of the u ltrapure water diaphragm valve.The results show that: the pneum atic ultrapure water diaphragm valve The slope of the flow-pressure characteristic curve is a fixed value,and the slope of the flow-pressure characteristic curve of the manual ultrapure water diaphragm valve has an inflection point at 99 Kpa,and the slope of the flow-pressure characteristic curve before 99 Kpa is higher than 99 Kpa The slope of the subsequent flow-pressure characteristic curve;in addition,the flow gain line of the pneumatic ul trapure water diaphragm valve is a fixed value,while the flow g ain of the manual ultrapure water diaphragm valve shows a trend of first increasing and then decreasing;at the height of the diaphragm rise In the same situation,the difference between the f low-pressure difference characteristics in the valve cavity of t he pneumatic ultrapure water diaphragm valve and the manual ultrapure water diaphragm valve is mainly due to the fact that the two control methods make the valve port open during the opening p rocess of the diaphragm.The variable produced by the diaphragm shape is different.Secondly,the influence of two control methods on the diaphragm and the main forms of diaphragm failure during the o pening and closing process of the ultrapure water diaphragm valve are analyzed.The results show that: for the ultrapur e water diaphragm valve with low pressure and small flow.The flow field has little effect on the stress of the diaphragm during the opening and closing process.The main factor of diaphragm failure is the fatigue damage caused by mechanical stretching;th e stress on the diaphragm of the ultrapure water diaphragm valve has a linear relationship with the valve opening.The stress peaks at the maximum valve opening state;the ultrapure water diaphragm valve has obvious stress concentration in the deformation area,and it is mainly concentrated on the outer surface of the diaphragm.During frequent opening and closing processes,there may be particles on the surface of the diaphragm.Falling off causes secondary pollution of the medium.Thirdly,the multi-objective genetic algorithm is used for the optim ization of the ultrapure water diaphragm valve diaphragm,the target parameters are set,the targ et parameters are calculated and selected,and the geometric parameters of the optimized diaphragm are obtained,so that the stress change during the opening and closing process of the diaphragm is more uniform and its maximum The stress is significantly reduced.The research results of this subject show that: the flow characteristics of the valve port of the pneumatic drive mode are significantly better than that of the manual control valve;in the low-pressure and small-flow diaphragm valve,the flow fiel d has less influence on the stress of the diaphragm during the opening and closing process,and the main reason for the failure of the diaphragm is The factor is fatigue damage caused by mechanical stretching,and the maximum stress appears on the upper an d lower surfaces of the diaphragm,which can easily lead to the shedding of particles on the surface of the diaphragm and cause secondary pollution of the medium;in addition,the optimization scheme based on stress homogenization can make the diaphragm op en The stress change in the closing process tends to be uniform,and its maximum stress is significantly reduced.