Modeling Flexforming (Fluid Cell Forming) Process with Finite Element Method

Abstract

In this paper, the flexforming process is modeled by finite element method in order to investigate the operation window of the problem. Various models are established using explicit approach for the forming operation and implicit approach for the unloading one. In all analyses the rubber diaphragm has been modeled revealing that the modeling of this diaphragm is essential. Using the material Aluminum 2024 T3 alclad sheet alloy, three basic experiments are conducted: Bending of a straight flange specimen, bending of a contoured flange specimen and bulging of a circular specimen. By these experiments the effects of blank thickness, die bend radius, flange length and orientation of the rolling direction of the part have been investigated. Experimental results are compared with finite element results to verify the computational models.

Springback prediction of CP2 titanium sheets in hydroforming with membrane diaphragm process with finite element method

“…Friction coefficient between blank (Titanium) and die (Steel) was accepted as 0.365, according to Adamus [8]. A special scaling factor was applied for the contact stiffness between diaphragm and the die, also between the diaphragm and the sheet in order to compensate the bulk modulus differences between these materials [1].…”

“…Some studies are found in literature related to this process. Hatipoglu et al [1] studied about hydroforming with membrane diaphragm process, which was modeled by finite element method. Three experiments were conducted which is bending of a straight and contoured flange specimen and bulging of a circular specimen made of Aluminum 2024 T3.…”

Investigation of Effects of Material Dimensions on Wrinkling in Flexforming Process

“…Hatipoglu et al [10] investigated the effect of sheet thickness, die bend radius, flange length, and rolling direction on flanging of straight and convex contoured AA2024-T3 parts, both experimentally and numerically. They found that the die radius as well as the rolling direction both have insignificant effects on the wrinkling, whereas the flange length and the sheet thickness have significant effects.…”

The Evaluation of Process Parameters on Springback in V-bending Using the Flexforming Process

“…Sheet metal parts formed in this way are used especially in aerospace, automotive and home appliances sectors for producing prototypes and a variety of parts with complex geometries. The flexforming process has become prominent due to its advantages of lower die costs -by using only half of the die -easy modification of the dies after changes allowing fast try-outs, and production of highquality parts with less damage to the sheet -less wrinkling and tearing -than conventional stamping 1 . Moreover, the process has some capability to form several parts with varied and complex geometries in a single operation, forms complex geometric parts by high-pressure and produce high quality parts with tight-tolerances.…”

“…Finite element analyses are also used to simulate the flexforming process and predict defects 7 . The study carried out by Hatipoğlu et al determined that the effects of the rolling direction and flange length on springback are insignificant, while the die radius and sheet metal thickness have a considerable effect on springback in the bending of AL2024-T3 sheet metal material 1 . In another study by Hatipoğlu et al using the flexforming process, they aimed to determine the friction coefficient between the unformed sheet metal and the die surface in AL2024-0 sheet metal material through experimental and finite element analyses.…”