An Impact Attenuation Structure for Occupant Safety during Vehicle Rollovers

Rollover accidents are especially violent and cause greater damage and injury than other accidents. Airbags and seat belts are not designed for such conditions. They provide limited help during a rollover because of the vertical impact in the upside-down position. This paper discussed the mechanism of the rollover accidents and proposed a simple but effective impact attenuation structure, which can be attached to the top of the cars. Quasi-static compression is performed on silicone, EVA rubber, and foam to determine the stress-strain behaviors. Dynamic free fall experiments are conducted to investigate the impact of energy absorption of the materials. A 3-D printed aluminum model is developed as a scale mode of the car cockpit during the free fall experiments. A dynamic 3-axis acceleration sensor at 2 kHz, together with a computer is used for data acquisition. The final results show that EVA rubber is the ideal material that can effectively reduce the impact of the model from >40 g to 5.5 g. Foam is insufficient in energy absorption and unable to prevent the metal model from impact with the ground even when the attenuator is fully compressed. Silicone is also found incapable of reducing the g-force to a safe range during impact due to its high elastic modulus. In the end, an impact attenuation structure made of EVA rubber for real passenger cars is suggested to effectively improve the safety of the people during a rollover accident.