Investigation on wrinkling behaviors of metal thin-walled tube in pulsating hydroforming with axial feeding

Pulsating tube hydroforming with axial feeding is an effective method to improve the forming performance of thin-walled tube. A beneficial wrinkle can make the tube wall thickness more uniform and create a greater bulging height during forming process. The method of expressing the degree of wrinkle with geometrical and mechanical criteria is applied to distinguish the wrinkle types, and thus, the wrinkles can be divided into beneficial ones and harmful ones based on the deformation wrinkle features with different forming parameters. The wrinkling behavior in tube pulsating hydroforming with axial feeding was investigated in this article by experimental study, numerical simulation and theoretical analysis. The results showed that loading parameters had great influence on formability and wrinkling behaviors and that the beneficial wrinkles could be identified and used effectively by controlling the relation of wrinkling degree and forming parameters. Furthermore, the evolution processes of wrinkling behaviors in tube-bulging experiment were observed, the characteristics of wrinkling in every stage were analyzed and the relationship between wrinkling degree and forming parameters was established in the experiment.