Study on influence of notch triggers on absorption of energy for composite automobile crash box under impact loads

Abstract

In case of a crash due to collision of vehicles, effective impact energy absorption by the vehicle safety structure is significant as it reduces the damage to the vehicle and its occupants. Components made of composite materials have a more complex mode of deformation, unlike metals, which in general deform with buckling or bending modes. The deformation mode of the component made of a composite is of great importance as the energy absorption level depends on it. Deformation mode can be modified by introducing special geometric features known as triggers in the design of the crash box. A trigger can also be useful in achieving required deformation mode and thereby helpful in attaining target energy and force values. The present study focuses on the effect of geometric shapes along with three novel trigger types on the level of energy absorbed for the GFRP composite material passenger car crash box in a low-velocity impact, named as “RCAR Test” in the automobile industry. All possible combinations of four different types of geometric cross sections, namely, square, cylindrical, hexagonal, and decagonal, and three novel patterns of notch trigger, imparted to a GFRP crash box were considered for study in the present work. The force distribution, energy absorbed, and SEA (specific energy absorption) were estimated. The relative merit of crash boxes with different combinations of cross-sections and trigger types for these parameters was assessed. The best performing combinations made from various notch triggers and different cross sections of crash boxes have been identified.