Research on Bursting Behavior in Hydroforming of Double-Cone Tube

Abstract

Firstly, the geometry condition of useful wrinkles during the hydroforming of double-cone tube was given. Then the stress condition of useful wrinkles was given by formula between the parameters of wrinkles shape at the end of axial feeding and internal pressure, hoop stress and axial stress. The analytical results were compared with the FEM analysis and experiments results. The results show that the useful wrinkles must meet both the geometry condition and the stress condition. The geometry condition of useful wrinkles is that the area of arbitrary length of wrinkles is a little smaller than the area of corresponding die cavity. The stress condition of useful wrinkles is that shape parameter G is not smaller than the radius R at the top of middle wrinkle. That means the increment of thickness strain dεt is positive and no thickness thinning will occur during the calibration. When the wrinkles didn’t match geometry condition, the dead wrinkles or bursting will take place. And when the wrinkles didn’t match stress condition, the bursting at top of middle wrinkle will occur during the calibration.

Prediction of wrinkle types in tube hydroforming under pulsating hydraulic pressure with axial feeding

“…In this subsection, the two prediction formulas (11) and (25) are verified by comparing the wrinkle types in the experiments of the THF with axial feeding with the predicted results. After the critical geometry parameter h c for the GPM and the critical hydraulic pressure P c for the MPM are calculated by substituting the forming data of the experiments in Table 2 into equations (10) and (24), respectively, the two prediction formulas (11) and (25) are applied to predict the wrinkle type. The comparison between the prediction results and the experimental results is presented in Table 3.…”

“…Yuan et al. 10 proposed a geometric criterion and a mechanical criterion that a useful wrinkle in the conventional THF should meet. The geometric criterion was that the surface area of a wrinkle in an arbitrary length interval is smaller than the corresponding surface area of the die, while the mechanical criterion was that a given shape parameter of the wrinkle is larger than the radius at the wrinkle peaks.…”

“…9 explored the relationship between the loading paths and useful wrinkles via finite element (FE) simulation and experiments, and concluded that useful wrinkles could be achieved and applied to improve the formability of tubes by appropriately controlling the loading paths. Yuan et al 10 proposed a geometric criterion and a mechanical criterion that a useful wrinkle in the conventional THF should meet. The geometric criterion was that the surface area of a wrinkle in an arbitrary length interval is smaller than the corresponding surface area of the die, while the mechanical criterion was that a given shape parameter of the wrinkle is larger than the radius at the wrinkle peaks.…”

New Developments of Hydroforming in China

“…3,4) There is also a large potential market in China. 5,6) In China, comprehensive and systematic research and development has been conducted on fundamental, process, die and press since 1999. As the first R&D center of tube hydroforming in China, the Engineering Research Center of Hydroforming (ERCH) from Harbin Institute of Technology (HIT) has established its leader position in this field in China.…”