Continuous glass fiber layers designed to withstand bending and torsional stress

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  • Multiaxial, reinforced Tepex for backseat load-through of an off-road vehicle
  • Over 40 percent lighter than steel counterpart
  • An efficient one-shot process
  • In addition: High level of function integration

Continuous-fiber-reinforced, semi-finished thermoplastic composites are now finding new applications in vehicle interiors. One example is the backseat system of an off-road vehicle made by a European automobile manufacturer. The center backseat is equipped with a load-through that enables the backrest of each seat to be folded down individually. This load-through component is produced by shaping and back-injecting Tepex dynalite.

Over 40 percent lighter than steel counterpart

The new component is more than 40 percent lighter than its steel counterpart. At the same time, this safety-relevant component withstands all load scenarios, because the orientation of the continuous fiber layers in the only two millimeter-thick semi-finished product is designed to bear the mechanical stress. The component was developed by Brose Fahrzeugteile GmbH & Co. KG in cooperation with Lanxess High Performance Materials business unit. Brose manufactures the component at its site in Coburg, Germany.

The load-through component is fabricated by shaping and back-injecting Tepex dynalite. The part marks the entry of this composite material into the lightweight design of backseat systems.

The load-through component is fabricated by shaping and back-injecting Tepex dynalite. The part marks the entry of this composite material into the lightweight design of backseat systems. Photo: Lanxess AG

Strong in case of front and rear crashes

For functional reasons, the load-through is only mounted on one side, at the top of the rear seat’s backrest. Because of its position, it is exposed to both bending and torsion forces. To withstand these load scenarios, a special multiaxial design was chosen for the continuous-glass-fiber layers in the thermoplastic composite. The semi-finished product for the load-through has a core consisting of four layers, each 0.25 millimeters thick, which have a fiber orientation of +45 and -45 degrees relative to the component’s longitudinal axis and are arranged symmetrically. They absorb the torsion forces. In contrast, the bending forces are absorbed by the two outer layers, each 0.5 millimeters thick, in which 80 percent of the continuous fibers are in the direction of force. In case of a frontal collision, this multiaxial layer design ensures that the component withstands the impact of the accelerated load in the trunk and, in case of a rear collision, the inertia forces pressing the passenger into the seat.

The process: An efficient one-shot process

To manufacture the load-through, a blank of the semi-finished product is heated, placed in the injection mold, shaped and back-injected with a glass fiber reinforced thermoplastic. In addition to ribbing that lends the part high stiffness, numerous functional elements are integrally molded on the component in the injection molding step, such as mounts for the headrest, various mounting points and screw connections, and the surrounding groove to which the rear, textile covering of the load-through is mounted. With a conventional steel design, this functional component would have had to be welded or screwed on separately.

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