Plastic frunk doubles as a chassis component thanks to Tepex reinforcement
Envalior and Röchling Automotive have developed a polypropylene frunk reinforced with multiaxial Tepex organosheets. The component combines storage with a load-bearing function in the chassis of an electric sports car.
A polypropylene frunk reinforced with Tepex organosheets has been introduced in a fully electric, four-door high-performance sports car from a German premium automaker. Manufactured by Röchling Automotive in Worms, Germany, the component combines storage space with a structural function in the vehicle chassis. Envalior plans to present the application at Fakuma 2026. Tepex reinforcement is incorporated into the rear wall and bolted floor sections of the frunk. The thermoplastic composite contains fabrics made from multiaxially oriented continuous glass fibers, providing the strength required to withstand loads generated during sudden lane changes, exposure to crosswinds and racetrack driving. The component connects a strut brace to the front-axle carrier and acts as a vertical shear panel, stiffening the front axle and contributing to road contact and driving stability.
Production in a single process step
The term "frunk" combines "front" and "trunk". In electric vehicles, the storage compartment occupies the front-end space where the engine is located in vehicles with an internal combustion engine. It can be used to store charging cables, tools and other items.
The frunk measures approximately 1,100 mm in length, 450 mm in width and 370 mm in height. Röchling developed a hybrid molding process that combines thermoforming of the Tepex organosheet with injection molding in a single mold. This allows a fully finished component that requires no reworking to be produced in one manufacturing step.
"Beyond the frunk’s design as a highly load-bearing chassis component, the manufacturing process we developed represents another key highlight of the application. Achieving uniform mold filling despite the complex geometry – while simultaneously minimizing weld lines to ensure the part’s high mechanical performance – was particularly challenging," says Matthias Schütte, Global Product Manager for Structural Lightweight Design at Röchling Automotive.
Fiber orientation adapted to the load paths
The component is reinforced with a multilayer Tepex organosheet. Continuous fibers are oriented at 0° and 90° in the outer layers and at +45° and -45° in the inner layers. This multiaxial laminate architecture is adapted to the direction-dependent combination of tensile, bending and shear loads acting on the part. The 0°/90° fibers primarily improve crash performance, while the ±45° fibers support vehicle dynamics under extreme lateral loads.
During dynamic maneuvers, off-road driving or high-speed cornering, lateral forces can twist the front body structure. The torsional stiffness of the frunk is intended to prevent this deformation. The component is bolted to the strut brace at its upper flange and to the front-axle carrier at the bottom, allowing it to function as a vertical shear panel.
The polypropylene frunk is reinforced in its rear wall and floor attachment areas with a multiaxially reinforced Tepex organosheet. As a result, it can withstand the high loads encountered by the vehicle body in extreme driving situations
"As a producer of organosheets, we have unique expertise. We can produce customized multilayer organosheets in high-volume production with continuous fibers oriented not only at 0° and 90°, but at virtually any angle required. This allowed us to engineer a customized organosheet for the frunk whose fiber orientations follow the exact load paths within the component, making it precisely adapted to the load-specific requirements," says Dr. Klaus Vonberg, Sales & Project Manager Global Sales Tepex at Envalior.
According to Envalior, the multiaxially reinforced organosheets can withstand high degrees of forming. The fabric layers resist fiber displacement and remain intact at component corners, supporting repeatable forming and consistent part quality.
Further integration through hybrid molding
According to Vonberg, the hybrid molding process could enable future frunks to combine more complex geometries and additional functions with structural duties in the vehicle body. Features can be integrated directly into the component during high-volume production.
"In the future, it may be possible to integrate features such as cool boxes, drawers, cargo nets, or holders for the charging cable directly into these frunks," Vonberg notes.
Further information about Envalior materials is available through the company’s MaterialAdvisor, which provides digital tools and services for finding, selecting and evaluating materials.
