Leverkusen - A new generation of injection-molded structural inserts with a carrier made of Durethan® BKV 35 H2.0 glass fiber-reinforced polyamide 6 has been developed on CBS-Technology (Composite Body Solutions) from CORE Products and deployed in the new Citroën C4 Picasso to achieve a major weight saving and much improved passenger protection in the event of an accident. The insert elements are integrated specifically in crash-relevant parts of the body, namely the lower part of the A-post, the lower and bottom parts of the B-post and in the cross member above the rear axle. "The nine inserts bring a weight saving per vehicle of around 12 kg. At the same time, they help to make the C4 Picasso one of the few vehicles to pass the Euro NCAP crash test with the top mark of five stars," explains Ulrich Dajek, a specialist in the Semi-Crystalline Products business unit at LANXESS. CORE Products is responsible for the fully assembled reinforcing inserts which are manufactured in Vigo, Spain. CORE Products and LANXESS cooperated closely in their development.

The polyamide inserts are used together with a “high-density structural foam". The CBS-Technology is creating a macro-structure together with the car body structure by the expansion of the foam and the bonding to the body in white during the drying process once cathodic dip coating (EDC) is complete. "Our polyamide has the enormous advantage over polypropylene that it is still heat-stable at temperatures of around 200 °C typical for EDC applications," says Dajek.

In the event of an accident, the inserts increase the load resistance of the body, and they absorb some of the impact energy, minimizing the deformation of the passenger cell and affording better protection to the occupants.

Apart from reducing weight and improving the crash behavior, the use of reinforcing elements has other advantages. For example, they improve the torsional rigidity of the body, so that there are no troublesome vibrations to impair the driving characteristics. At the same time, they provide a certain amount of acoustic insulation.

LANXESS offers a wide-ranging service for the development and design of inserts for car body reinforcement. "Our development partners benefit in particular from the fact that we can determine the strain rate-dependent material data for our products with the aid of high-speed tensile tests. From this it is possible, using conventional crash simulation programs such as LS-Dyna or PAM-Crash, for example, to calculate the strength, energy absorption and dynamic loadability of the inserts and assess their crash behavior reliably and realistically," says Dajek. Furthermore, the experts at LANXESS have wide-ranging know-how on how the reinforcing elements have to be designed to adapt them perfectly to suit the steel environment. The specialists also assist cooperation partners in all matters of fixing the inserts, testing the parts and selecting the processing techniques.