| In recent years, integral forming substituting welding in groups is paid attention in many respects to improve the performance of structure of shell in aviation and automobile industry. Thin-wall parts with variable diameter are one of the models. In this paper, experimental and finite element study of stainless thin-wall (1Cr18Ni9Ti) parts of variable diameter with viscous medium outer pressure compression forming are carried out for the new forming method of thin-wall parts with variable diameter with viscous medium outer pressure compression,.Compression behavior with the two conditions of end fixing and end free is analyzed by analytic expression. Characteristic of stress-strain with end fixing and critical pressure in buckling with end fixing and end free are confirmed. Critical dimension of wrinkles of specimen which can be banished is proposed during viscous medium outer pressure compression process.The influence of injection loading on the distribution of pressure field of viscous medium and influence of the tow conditions on the compression process of specimen are analyzed by finite element method. And the influence rule of diameter and wall thickness, length of compression region and the ratio of length to diameter on the stability and magnitude of compression limit and variation of wall thickness and characteristic of strain of specimen is confirmed under the condition of end fixing.Experiments are carried out to validate the results of finite element. Results show that the ability of specimen to resist buckling can be improved by restricting ends material flowing to compression region under the condition of end fixing. With the end fixing condition, the magnitude of compression limit is increasing as the increasing of diameter of specimen; however the magnitude of compression limit is decreasing as the increasing of length of compression region and the ratio of length to diameter which are coincident with finite element's.
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