Effects of Diameter-to-thickness Ratio on Impact Energy Absorption Capability of CFRP Cylindrical Crash Box

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Effects of Diameter-to-thickness Ratio on Impact Energy Absorption Capability of CFRP Cylindrical Crash Box

Choi, Soo-young / Hong, Seung-chul / Park, Sun-kyu / Jeong, Sang-won

Modern cars protect drivers and passengers in frontal, rear and offset crashes by using crumple zones to absorb crash energy. This means that the car absorbs the impact of the crash, not the driver or passengers. Crumple zones allow the front of the vehicle to crush like an accordion, absorbing some of the impact of the collision and giving some off in the form of heat and sound. The front of the vehicle effectively acts as a cushion that slows the time it takes for the vehicle to come to a complete stop, applying less force on passengers, which could help save their lives. For vehicle frontal collision protection, it is then very common to see cars equipped with an energy absorbing crash box, which is attached on front side member (FSM), and the use of advanced polymer composite materials in the crash box has been actively considered in recent years. In this paper, the crashworthiness of a conventional metallic crash box has been assessed through drop-weight tests and CAE simulation, and expected advantages when CFRP composite material is applied to the crash box has been also analyzed. As a result of the study, it was found that the impact absorption performance of the composite crash box is at least 1.5 times better than the conventional metallic (aluminum) crash box, when considering lamination that can lead to pure compression failure of the composite crash box. In addition, the energy absorption performance decreases as the inner diameter increases with the same shell thickness, and especially, when the content of the 0° oriented layer is less than a certain level, the performance of the specimens was significantly degraded as the inner diameter of the specimens increased.