REALISTIC SIMULATION OF HEAD, HIP AND LEG IMPACT
15 June 2004 - Bayer MaterialScience AG

Bayer MaterialScience AG can now call on virtual, validated testing elements called impactors to realistically simulate the impact of the leg, hips and head (adults and children).

"We can produce an exact analysis showing our customers how to optimize the design of a front end, including all the add-on parts, to comply with the stricter requirements. Through this realistic simulation, the building of prototypes becomes superfluous. This means shorter development times and fewer practical tests," explained Roland Brambrink, a Computer Aided Engineering (CAE) expert in Bayer MaterialScience's Business Development section.

The fact that the impact can be simulated with an extremely high degree of accuracy is also due to a new process that enables Bayer MaterialScience to determine the crash-related data of thermoplastic materials very precisely indeed. The new evaluation method for high-speed tensile tests is based on "reverse engineering". "We can also derive, quickly and accurately, the crash data of thermoplastics that have a tendency to constrict in tensile tests. Formerly, it was only possible to derive such data for these materials – if at all – with the aid of a complex trial-and-error procedure. We are now also in a position to determine the data as a function of load velocity," added Brambrink.

Just how well the design of a front end performs during the crash simulation with the impactors depends not only on the overall design, but also on the materials used to manufacture the various components of the front of the car. A good example is the headlamp lens. In accidents with children, the headlamp is often struck by the child's head, which is why the HIC index (head injury criteria) is such an important yardstick for this component. "It shows why it is essential for the designer to have accurate crash data. It is a big advantage for our development partners that a large number of the plastics used in the front end of a car are part of our product portfolio, so that we also have the relevant material data," said Brambrink. For example, headlamp lenses are made of Makrolon®, radiator grilles are made of Durethan® polyamide and Pocan® polybutylene terephthalate, while energy-absorbing pads in the bumper are made of semi-rigid Bayfill® EA polyurethane foam.

The commitment made by the 13 European car, truck and bus manufacturers, who are organized in the Association des Constructeurs Européens d' Automobiles (ACEA), also provides for stricter load thresholds for the head impact of children and adults, as well as for hip impact. 80 percent of the newly registered vehicles will have to comply with the stricter requirements by 2010, and all new vehicles by 2012 at the latest. The commitment will cover around 80 percent of the car market in Europe, and will also include vehicles exported to Europe by the U.S. auto industry.

http://www.bayermaterialscience.com

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