A rocker panel isn’t usually the star of the show. It lives hidden under the door, nobody looks at it at a motor show, and yet it’s the part that decides what happens to an EV battery in the worst-case scenario: a side impact against a pole.

That was the starting point of our latest technical study: how much additional performance can be extracted from an extruded aluminum profile —already optimized, already lightweight, already cheap to manufacture— without touching its production process?

Current rockers for mid-sized SUVs sit around 19 kg per vehicle and are manufactured by extrusion or stamping in metal. It’s a compromise solution: solid mechanical performance, contained weight, industrial scalability. But side-impact safety regulations (FMVSS 214, with the oblique pole test) are demanding more every year, and that extruded aluminum is starting to hit a ceiling.

The question wasn’t “do we change material?” It was “can we reinforce what already works, without redesigning the production chain?”

The solution: continuous fiber exactly where it’s needed

This is where CFIP comes in. Instead of replacing the aluminum, we inject continuous carbon fiber together with liquid resin into internal channels already built into the extruded profile itself. Three 8 mm CFIP units, placed precisely at the impact face of the rocker.

The result isn’t new material. It’s the same extruded aluminum as always, with internal reinforcement directed exactly where the impact needs it. No mould changes, no process changes, no giving up the scalability that makes extrusion viable in the first place.

Two finite element models were built in Ansys —benchmark and CFIP-reinforced version— under the same side-impact conditions. The results:

• +55% in absorbed energy
• +41% in specific absorbed energy (i.e., per kg of structure)
• Deformation distributed over a significantly larger area, instead of concentrating at a single point

Deformation plots for the benchmark (left) and CFIP (right) rockers.

Translated: the reinforced structure doesn’t just withstand more, it withstands better. It deforms in a more progressive and stable way, delaying the localized failure mechanisms that are the ones actually putting the battery at risk.

Why this matters beyond the rocker

The interesting data point isn’t just the +55%. It’s that this improvement is achieved while keeping the industrial advantages of extrusion fully intact: cost, scalability, compatibility with existing production lines. And the approach isn’t limited to straight profiles either: CFIP also enables the manufacturing of curved reinforced geometries, expanding the design space beyond traditional extrusion.

This opens the door to extrapolating the solution to other vehicle components that need more stiffness, more impact resistance, and less weight, without having to reinvent how they’re manufactured today.

The study makes clear this is a starting point, not a ceiling: the number of reinforcements, their distribution, and the shape and thickness of the aluminum profile all still have optimization potential ahead.

How much additional performance are we leaving on the table in parts we already considered “solved”?

📩 Contact us for technical consultation or to request sample components.

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