CONTINUOUS-FIBRE-REINFORCED BACKSEAT 40% LIGHTER THAN STEEL COUNTERPART
TEPEX dynalite continuous-fibre-reinforced, semi-finished thermoplastic composites are finding new applications in vehicle interiors.
One example is the backseat system of an off-road vehicle made by a European automobile manufacturer. The centre 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.
“The part marks the entry of this composite material into the lightweight design of backseat systems and is further evidence of its enormous potential in series production applications,” says Henrik Plaggenborg head of technical marketing & business development with Tepex Automotive.
“The new component is more than 40% lighter than its steel counterpart. At the same time, this safety-relevant component withstands all load scenarios, because the orientation of the continuous fibre layers in the only two millimeter-thick semi-finished product is designed to bear the mechanical stress,” explains Harri Dittmar, project manager and Tepex applications specialist.
Tepex is manufactured by Lanxess subsidiary Bond-Laminates, which is based in Brilon, Germany.
The lightweight component was developed by Brose Fahrzeugteile with support from the Lanxess High Performance Materials business unit. Brose manufactures the component at its site in Coburg, Germany.
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-fibre layers in the thermoplastic composite. Multiaxial Tepex is a new development from Bond-Laminates, which makes the composite sheets significantly stronger than before by combining the Tepex fabric with tapes in a technically complex process.
The semi-finished product for the load-through has a core consisting of four layers, each 0.25mm thick, which have a fibre 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 0.5mm thick, in which 80% of the continuous fibres are in the direction of force.
“In case of a frontal collision, this multiaxial layer design ensures that the lightweight 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,” explains Dittmar.
Efficient one-shot process
To manufacture the load-through, a blank of the semi-finished product is heated, placed in the injection mould, shaped and back-injected with a glass fibre reinforced thermoplastic. In addition to ribbing that lends the part high stiffness, numerous functional elements are integrally moulded on the component in the injection moulding 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.