Lightweight construction is becoming increasingly important in the automotive industry, as advancements in safety technology, electronics, and rising comfort expectations contribute to the overall weight of vehicles. The ongoing transition to electric vehicles, which are typically heavier than those with internal combustion engines, further amplifies the need for weight reduction elsewhere. To address this, the plastic polypropylene (PP) is widely used in vehicle interiors due to its low cost, ease of processing, and relatively good recyclability. However, polypropylene has notable drawbacks-specifically, its limited rigidity and heat resistance. To enhance these properties, glass fiber is commonly added, resulting in a glass-fiber-reinforced plastic known as PP-GFx, which is used in many Porsche vehicle components.

At Porsche Engineering, Michael Johann, Specialist Project Manager for Body System Development, and his team focus on developing series-production plastic components, such as roof linings for the Porsche Cayenne and trims for columns and doors. The team is continuously evaluating new design principles to achieve a balance between maximum strength and minimum weight. This pursuit led to the development of TABASKO, a tape-based carbon-fiber lightweight construction method.

Johann’s objective was to achieve superior material properties at a lower weight. Carbon fiber, known for being as strong as steel yet up to 80% lighter, was identified as a promising material despite its high cost. By embedding carbon fibers in a thin polypropylene film, the team created carbon fiber tape, which offers new possibilities for lightweight construction.

Johann hypothesized that reinforcing traditional PP with a few continuous carbon fiber tapes would allow for reduced wall thicknesses in components without compromising stability. The resulting decrease in PP-GFx usage could offset the higher cost of carbon. Calculations supported this hypothesis, and initial bending tests using carbon-fiber tapes ironed onto PP-GFx samples yielded promising results.

To advance the concept, Johann sought partners for implementation, leveraging the close collaboration between Porsche Engineering and Porsche AG. Materials expert Frank Häusler reviewed the concept and found it well-developed, with robust supporting data and a clear rationale. Dr. Hubert Stadtfeld, Project Manager for Lightweight Construction in Production Development at Porsche AG, also endorsed the project and assumed patronage. To secure funding for prototype development and validation, the concept was registered as an innovation project within the production department.

Successful Prototype Tests

In search of a suitable component for a prototype, the developers encountered the luggage tray of the Porsche Taycan. It is made of glass-fiber-reinforced plastic as standard and is manufactured in an injection molding process. The series component is 65 centimeters in length, 120 centimeters in width, and 52 centimeters in height, making it comparatively large.

“If tests on a large component are successful, then the results can also be applied to smaller components,” explains Johann. TABASKO now had to prove itself under professional conditions: Häusler and Johann produced a luggage tray made of 1.8-millimeter-thick PP-GFx, reinforced with 0.2-millimeter-thin carbon-fiber tape.

The special feature was that the percentage of carbon by weight only totaled one percent, because the continuous fibers are placed exactly at the points where they achieve the greatest effect. Three tests were carried out with the prototypes: First, a comparative punch test was carried out on both a current series-production luggage tray and on its counterpart made of TABASKO material. In the process, a punch was pressed onto the bottom of the tray from above with increasing force in order to measure how much it bent.

The result: For TABASKO, a 66% higher compressive force was required to achieve the same maximum permissible deflection, and the luggage tray was, at the same time, 15% lighter than the series-production luggage tray.

The second test was a series of trials consisting of four-point bending tests. To do this, the developers cut rectangular strips out of the bottom surface of the luggage tray. The strips were then bent from both sides, each at room temperature and at 90 degrees Celsius. “Clearly visible was that the rigidity of the tape-reinforced samples was higher by a factor of 2.5 to 2.8,” explains Häusler.

The third test determined the impact strength. This test is appropriate when foam injection molding is used, as it is in the manufacture of the TABASKO material.

“In doing so, this results in foam structures that could cause the impact resistance of the base material to suffer,” says Mr. Johann. The test showed that, in combination with tape on the tensile side, the impact resistance is approximately five times better. TABASKO proved its superiority here as well.

“Now came the most important step: Transfer to series production,” as Häusler reports. “The question was: How can you produce up to 80,000 parts a year— in a fully automated way and cost-neutral compared to today’s process?”