Sheet metal hydroforming(flexforming) is a process generally used in the manufacturing of aerospace parts in which a rubber diaphragm forms the sheet on a die with the help pressurized fluid and by this aspect it is different from the conventional stamping process. Some defects occur in the parts that are manufactured by this method and they are not different from the general sheet metal forming defects. Wrinkling, tearing and springback are among those defects. Variety of parts makes difficult to encounter these defects arising the detailed investigation of this process.
In this work, the flexforming process was modeled by finite element method in order to investigate the operation windows of the problem. Various two and three-dimensional models were established with and without diaphragm, using explicit and implicit approach for time integration and using solid and shell elements for the blank. Using the material Aluminum 2024-T3 alclad sheet alloy, three basic experiments were 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 and forming pressure have been investigated. Experimental results were compared with finite element results to verify the computational models. Then, three selected aerospace sheet parts were analyzed and success of the model in the real life applications is proved.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12608755/index.pdf |
| Date | 01 September 2007 |
| Creators | Hatipoglu, Hasan Ali |
| Contributors | Dursunkaya, Hasan Ali |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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