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Sung-Yun Lee 1 and Dae-Cheol Ko 2 and Sang-Kon Lee 1 and In-Kyu Lee 1 and Myeong-Sik Joeng 1 and Da Hye Kim 1 and Yong-Jae Cho 1
Academic Editor:Woo-Jin Song
1, Ultimate Manufacturing Technology R&BD Group, KITECH, Daegu 711-883, Republic of Korea
2, ERC for ITAF, Pusan National University, Busan 609-735, Republic of Korea
Received 28 February 2014; Accepted 27 April 2014; 8 July 2014
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. Introduction
Recently, with the increase in air pollution levels and depletion of fossil fuels, global warming has reached unprecedented levels. As a result, it has become essential to develop light, high-mileage transport machineries, which is a big challenge in itself. Several studies, with focus on developing state-of-the-art manufacturing technologies, have been carried out to produce light transport machineries by employing vehicle parts made of light materials such as aluminum and magnesium [1, 2].
The weight of a vehicle directly affects its mileage, and, therefore, reducing the weight of all parts of the vehicle, including body, frame, and chassis, is essential. A bumper with a dual-frame structure, installed in the front and rear of a vehicle, ensures the driver's safety during collision by absorbing and distributing collision energy [3, 4]. Earlier, bumpers were made of iron beams, which increased the weight of the vehicle. However, nowadays, with the development of composite materials, lightweight bumpers having sufficient impact strength are produced. Nevertheless, producing bumpers that can ensure safety and are lightweight remains a challenge. Several studies have recently been conducted on bumpers employing lightweight materials [5, 6], and it has been found that such bumpers have complex cross-sectional shapes and are longer. Thus, during the deformation of such lightweight bumpers, various problems are encountered. In particular, oxidation on the surface occurs in case of a magnesium alloy at high temperatures, when hard-to-deform materials are used during the deformation process. Furthermore, deformation of plastic occurs, and it becomes hard to determine the appropriate process conditions required to be established when high temperatures are achieved during the process [7]. Ultimately, it becomes difficult to maintain the quality and appearance of the product.