Enhancing Safety and Crashworthiness of Vehicles Using Composite Metal Foam

Novel steel composite metal foams (CMFs) are lightweight materials made from stainless-steel hollow spheres, with entrapped air suspended within the stainless-steel matrix. In this work, the performance of CMF-core front rails, containing steel CMF within an aluminum 6061 alloy double tube, is compared against rectangular high-strength low-alloy (HSLA) 350 steel and double-octagon aluminum 6061 alloy front rails of equivalent masses and lengths. Explicit finite element models of different front rails are subjected to frontal impact with entrapped air within the CMF core modeled using the pneumatic fluid cavity technique. The inclusion of a steel CMF-core within the double-tube structure results in plateauing vehicle deceleration instead of pulsating behavior observed during the buckling of tube-only structures. CMFs containing pressurized air and core–tube interactions enhance the compressive resistance of front rails to prevent localized bucking. The CMF-core front rail increases the accident velocity required to exceed the critical accident severity and head injury criterion (HIC) by 33.73% and 39.50%, respectively, when compared to an equivalent double-octagon front rail and by 31.93% and 48.24%, respectively, when compared to an equivalent rectangular front rail. The research demonstrates that utilizing novel energy-absorbing steel CMFs within automotive front rail structures helps improve occupant safety for crashworthiness applications.