| Metal bellows used for the manufacture of various sensitive components,compensation components,flexible connectors and heat-exchange components,mainly used in aerospace,aviation,automotive,shipbuilding,petrochemical and other industries,especially in the advanced aeroengine,it can fill the gap between the seal ring and shaft,greatly enhance the structure of the sealing performance,improve fuel efficiency.With the continuous development of industrial technology,structural lightweight is an effective way to reduce the cost and low down the weight,and also meet the need of strength and stiffness of the material.Titanium alloy is light in quality,it has good mechanical properties and corrosion resistance to become a new type of metal bellows material,in line with the structure of lightweight development trend in the aviation,aerospace,chemical and other industries,it would have good prospects for development.As the titanium alloy elastic modulus is small,poor plasticity,difficult to form,so there is no much current research and application in China.Based on the elastic-plastic finite element model,the hydroforming process of titanium alloy bellows is designed by Johnson-Cook plasticity element model and ductile damage principle.An symmetrical finite element model with an outer diameter of 21.5 mm,a wall thickness of 0.16 mm and a maximum diameter of 31.5 mm when it is formed.The whole process from the initial loading of the hydroforming pressure to the end of the springback is simulated,and make a relative analysis between stress-strain distribution,prediction of the crack location and the related actual production to verify the rationality of the finite element model.In order to prevent the occurrence of defects such as cracking,on the basis of ensuring the maximum reduction rate and the maximum damage variable D,the same time to reduce the amount of spring,the die fillet radius,hydroforming pressure size and die spacing and other process parameters Optimization,get the best process parameters,and then get the relevant process parameters on the bellows hydroforming the law.Using the optimized process parameters,the springback of bellows is 4.7mm,the maximum thinning rate is 32.02%,and the maximum damage variable D is 0.5.According to the process parameters after the optimization,a set of bellows hydroforming mold which is designed and processed,and finally complete the preparation of titanium alloy bellows.Comparison of experimental results and simulation results in the length direction of the thinning rate,to verify the finite element analysis accuracy.The results show that the thinning rate of the finished bellows is larger than that of the simulation results.There is a difference of 2%-3% at the maximum reduction rate of the peak,and there is a difference of 1% to 2% at the end of the tube,which is due to the assumption that the simulation process Is the total lubrication(friction coefficient of 0.08),the experimental process may not be all lubrication,the greater the coefficient of friction,the greater the reduction rate caused by the results.In this paper,the Abaqus script file is edited by using the Qt Designer visualization interface and the connection language is edited in Python.The interface is connected to Abaqus to complete the secondary development of Abaqus.According to the interface of the process parameters,geometric parameters and finite element parameters to enter the relevant data,you can automatically generate CAE files and complete the calculation to generate the relevant results report,according to the report to modify the parameters,and complete the process optimization of the hydroforming bellows,with practical significance. |
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