Analysis and experiment on wrinkling suppression for hydroforming of curved surface shell

摘要

Wrinkling on the unsupported area of some deep drawn shells with curved surface and thin thickness is extremely hard to control. Sheet hydroforming process is of concern to eliminate this defect, but the analytical prediction of a proper liquid pressure path is far from perfection. In this article, an analytical model on the wrinkling suppression for the hydroforming of curved surface shell was proposed and achieved by the combination of stress model and geometrical model. An experimental setup and simulation model were designed to verify the accuracy of analytical model. The mechanisms for the wrinkling-suppression effect of the liquid pressure were analyzed by stress analysis. What's more, the effects of different parameters for the required liquid pressure were discussed using multiple linear regression analysis. Results show the proper liquid pressure can be used to form wrinkling-free shell. Both the experimental results and the stress distribution agree well with the analytical prediction. The most influential parameters for the liquid pressure are the axis length ratio and the surface quality of the punch. It can be seen that the sheet hydroforming process is very effective for the wrinkling suppression of deep drawn shells with large area of unsupported area, meantime the analytical model can be used in engineering applications and reducing simulation time. (C) 2015 Elsevier Ltd. All rights reserved.