Maximizing the Energy Absorption Capacity of Thin Walled Box Structures Using Ultra High Strength Steels (UHSS) at Sensitive Zones

Thin walled front-end box structures play a significant role in absorbing the collision energy in case of frontal impacts. Maximizing energy absorption within the constraints of available space, weight, cost and the average impact force that will not deteriorate occupant safety is challenging. Past research suggests that the structural shape, the use of high strength materials, and a combination of foam filled structures significantly improve the energy absorption capacity. This paper presents a new methodology to maximize the energy absorption capacity by means of optimum material combinations of low and high strength steels at sensitive locations. A Finite Element Analysis (FEA) methodology has been formulated with a simple square shaped crush box of a mild steel material and subsequently with combination of mild steel and high strength steels at sensitive zones of the crush box to improve the energy absorption capacity. Similar set of simulations are repeated with circular shape and the results are compared. The significant factors affecting the energy absorption which are critical to occupant safety has been compared between the simulations. It is noted that more than 90% of specific energy absorption capacity can be increased by using the optimum combination of mild and high strength steels at the sensitive zones of the structure. The methodology has been applied on the full vehicle crash simulation and demonstrated the benefits in reducing the structural intrusions. This proposed methodology has potential to be used in low-cost, lightweight applications.