Image Courtesy: NC State University

Researchers at North Carolina State University have developed a composite metal foam that could improve how vehicles absorb energy during high-speed frontal crashes. Computer simulations found that front rails filled with the material reduced crash forces and injury-related measurements compared with conventional rail designs of the same weight and length.

The material consists of thousands of hollow stainless steel spheres embedded in a stainless steel matrix. When placed inside an aluminum front rail, the structure is designed to collapse progressively during an impact rather than buckle suddenly at a single point. The research was led by Aman Kaushik and Afsaneh Rabiei, a professor of mechanical and aerospace engineering at NC State.

The simulations, <a href=”https://www.earth.com/science/metal-foam-car-crash-safety/”>according to Earth.com</a>, compared the foam-filled rail with two conventional designs: a rectangular steel rail based on a truck design and a double-octagon aluminum rail used in a modern sedan.

At 55 mph, the composite metal foam rail reduced peak deceleration and peak force by about 38% compared with the double-octagon design. Measures associated with overall crash severity and head injury risk were each reduced by roughly 45%.

The differences were even larger against the rectangular steel rail. At the same speed, that design reached full compaction and delivered a substantial final force, while the foam-filled rail reduced the corresponding measurements by about 84%. The simulated accident-severity measure was approximately 16 times lower, while the Head Injury Criterion, or HIC, was about six times lower.

The researchers also found that the foam-filled structures could tolerate higher impact speeds before reaching critical injury thresholds. One design crossed the severity threshold at 60 mph and the HIC threshold at 77 mph, approximately 34% and 40% higher than the comparable double-octagon rail.

The results come with an important limitation: no physical vehicle crash has been conducted using the material. The study relied on computer simulations and did not model seat belts, airbags, or crash-test dummies. The authors say the work is intended to compare front-rail designs rather than replicate an official vehicle safety test.

Rabiei said the material could potentially allow automakers to shorten front rails while maintaining or improving crash protection, potentially reducing vehicle weight and improving efficiency. The team is also exploring applications in electric vehicles, including battery protection, where the material’s heat and fire resistance could provide additional benefits.

The researchers plan to conduct physical testing under National Highway Traffic Safety Administration protocols. Until those tests are completed and independently evaluated, the promising results remain a simulation-based indication rather than proof that the technology can make production cars safer.