Investigation into Detection Criteria for Wrinkling in Tube Hydroforming

One of the most common non-traditional forming process, is the tube hydroforming, which is widely used for to form various tubular parts. To produce final product without any failure, tube hydroforming process is strictly dependent on load path, internal pressure-axial feed. Major modes of failure which may be occur in tube hydroforming process are necking, bursting, buckling and wrinkling. Predicting and preventing each of these failures are very important and leads to defects-free products. In this study, geometrical criteria for detecting wrinkling in numerical methods such as finite element analysis are reviewed. This type of identifying the wrinkling can be pointed out such as the first derivative or geometric slope and length to area indices criteria. In this paper, a new geometric method as a center of volume is introduced. In this case, the center of volume of wrinkled part is not equal with the wrinkled-free one. In order to verify, the results of this new criterion were compared with the results of previous measures and experimental tests in published articles.