Study On Temperature Difference Prestressed Autofrettaging Technique Of External Pressure Cylinder

Pressure vessels are widely used in various industrial sectors.With the development of production technology,higher requirements are put forward for external pressure vessels.How to take corresponding measures to further improve the bearing capacity of external pressure vessels is the key content that designers need to consider.Autofrettage treatment is an effective measure to improve the bearing capacity of pressure vessels.The key of autofrettaging treatment is how to make the container get good prestress before it is put into production.Autofrettaging technology of temperature difference prestress is applied to pressure vessel.Its operation mode is to apply temperature difference load on the inner and outer sides of cylinder body,and clear the temperature difference load after stabilizing for a period of time.At this time,favorable residual prestress is formed in the wall of the vessel,which can improve the bearing capacity of pressure vessel.Compared with traditional autofrettage technology of mechanical stress,this autofrettaging technology has the advantages of safety,economy,flexibility and convenient operation.Considering the increasingly wide application of external pressure vessels,this paper takes the external pressure cylinder as the research object,implements the temperature difference prestress autofrettaging technology,and discusses the operability of the temperature difference prestress autofrettaging technology by analyzing the internal stress distribution in the cylinder wall.The main contents are as follows:Firstly,according to the theoretical knowledge of elastic mechanics and plastic mechanics,the autofrettagement theory of elastic temperature difference prestress and elastic-plastic temperature difference prestress are studied respectively for the external pressure cylinder with open ends and closed ends.In this process,in order to find the critical temperature difference value of yielding,it is necessary to discuss the stress distribution of external pressure cylinder under mechanical load and elastic temperature difference load,so as to obtain the stress distribution of external pressure cylinder during plastic deformation under temperature difference load,the stress distribution in cylinder after removing temperature difference load and the stress distribution of external pressure cylinder under the combined action of mechanical load and temperature difference load.MATLAB mathematical software is used to calculate the data of this example,and ORIGIN function drawing software is used to draw the figure of the example.ANSYS WORKBENCH finite element software is used to simulate and analyze the elastic comprehensive stress and elastic-plastic comprehensive stress of the external pressure cylinder under two conditions of open ends and closed ends.By comparing the numerical solutions before and after the autofrettagement,the operability of the autofrettage technology is further verified,and problems needing attention and improvement are found.