Integrated Engineering Thermoplastic Crush Boxes as an Approach to Allianz Test

The primary purpose of an automotive bumper is to protect the vehicle from damage, which may otherwise result from a low speed impact. Major insurance companies typically conduct low speed crash tests of new vehicles in order to establish appropriate insurance classifications based on the estimated costs to repair the resulting damage. One such test, which is carried out by the Allianz insurance organisation, has become the European standard by which automobile insurance rates are set. Although commonly known as the Allianz test, it may be more specifically referred to as the Danner test, after Max Danner, the originator of the test. This test is conducted at 15 km/h with a 0° oriented rigid barrier overlapping 40% of the vehicle for frontal collisions and a 1000 kg moveable barrier with a 40% overlap for impacts to the rear of the vehicle. The level of performance achieved on this test can have an effect on how global platforms can compete in the European market due to higher insurance costs (higher cost of ownership) for poor performers. Currently, the most common countermeasures to reduce damage from this test have been various non-recoverable mechanical shock absorbers mounted between the frame rail and the bumper bar. Although effective in performing the function of an energy absorber, these systems add further weight and cost to the vehicle.

This paper will address alternative approaches for improving Danner performance through integration of engineered crush members to a thermoplastic bumper beam as well as separate thermoplastic absorbers used in conjunction with conventional bumper reinforcements. Examples will be given to demonstrate how an integrated thermoplastic systems approach can provide exceptional energy absorption performance without significant added cost and weight. Results of detailed impact simulations will be covered for both blow-moulded and injection moulded designs. Test data from a sub-component level Allianz test on a thermoplastic beam with integrated crush towers is also provided to demonstrate the potential energy management effectiveness of the approach.