Research On Autofrettage Technique Of Thick-walled Cylinders With Thermal Prestress

Thick-walled cylinders has become an indispensable equipment in many industries with the advances of technology.The pressure carrying capacity of thick-walled cylinders are more demanding than ever before.Therefore,how to increase its capacity and safety is a problem to researchers and mechanical engineers.Thermal autofrettage of thick-walled cylinders is a solution to this problem.The method involves radial temperature gradient in the cylinder,and it will induce beneficial compressive residual stresses around the inner wall of the cylinder.After the autofrettage,thick-walled cylinder become safer.Also,its pressure carrying capacity has increased a lot.The technology is practical because of its safety and simplicity.Based on the closed thick-walled cylinders,the numerical simulations and theoretical analysis of the different autofrettage stage in the plane-strain condition is carried out,which could demonstrate the feasibility.The main contents are as follows:In the first place,on account of the elastic-perfectly plasticity,this paper analyze the thick-walled cylinders theoretically.In order to solute the distribution of the elastic stresses,residual stresss and the critical tempreture,the different stage of autofrettage process is discussed.Secondly,the total stresses before and after autofrettage were compared.The maximum temperature that the cylinder couldn’t be yielded in the opposite direction were also discussed in this paper.Furthermore,the distribution of stresses were calculated by MATLAB,and shown on ORIGIN.ANSYS Workbench was used to build the mechanical model and analyze the process of thermal autofrettage.Last but not the least,this paper compared the analytic solution with numerical solution and showed the practical value.