| Abstract |
| A study on shape optimization of a hot-stamped automotive door impact beam for lightweight design and improved crash performance was conducted using a static collision analysis based on FMVSS 214. An integral type one-piece door impact beam of bracket parts and pipe was realized using hot stamping technology. The method involves the heating in the austenite region and subsequent hot forming and quenching in a specially designed stamping tool with hydraulic system. A one-piece door impact beam is 6.8% lighter than a three-piece door impact beam because it eliminates two bracket parts. The one-piece door impact beam was hot-stamped with dies without cooling channels inside the dies, and revealed a Vickers hardness higher than 430 and a fully martensitic microstructure. Two one-piece door impact beams, with a straight pipe with circular cross section and a straight pipe with partially circular and partially elliptical cross section in the middle part of the pipe, were used for the collision analysis. The door impact beam with partially circular and partially elliptical cross section showed less plastic strain in the middle part of the pipe compared with the circular pipe, leading to better intrusion property. Intrusion analysis results also showed that the three-pieces door impact beam fractured at a 336 mm displacement due to excessive plastic strain in the welded part between the bracket and pipe. In contrast, the integral type one-piece door impact beam without welding did not show any fracture, even at a 457.2 mm displacement, confirming the better performance against lateral collision.
(Received February 7, 2019; Accepted April 15, 2019) |
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| Key Words |
| automotive door impact beam, crash performance, lightweight design, hot stamping, one-piece door impact beam, pipe shape |
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