WP5 - Crash performance

The objective of this WP is to investigate the methods to evaluate the benefits of pre-crash systems during the crash phase of an unavoidable accident. To achieve this, data from work packages 1, 2, 3 and 4, and experience in passive safety, simulation and sled and full crash testing are being used. The result will be a complete set of testing and assessment protocols based on different strategies.
Safety improvements for vehicle occupants during the crash phase come mainly from two different pre-crash systems:
• Brake assist systems: To reduce the impact speed, thereby reducing, a priori, the severity of the injuries suffered by the occupants.
• Improved restraint systems: To enhance the dummy position when the impact occurs.
In order to assess separately the benefits of these two pre-crash systems during the crash phase, injury risk curves were defined as the suitable tool to be used. Each biomechanical criterion should have its own graph containing two curves, one considering the benefit of the improved restraint systems, and the other one without considering it. Find below an example of a graph representing the injury risk curves:

Each curve indicates the injury risk according to the impact speed, making it possible to quantify the injury risk reduction according to the impact speed reduction obtained due to the brake assist system activation.
The graph above shows two different curves: the blue one considers the benefits from the improved restraint systems; in contrast, the red one does not consider them.
Exemplifying by using the graph above, if red and green points are compared, it is possible to quantify the benefit coming only from the speed reduction. Otherwise, if black and red points are compared, it is possible to know the injury risk reduction coming only from the use of improved restraint systems.

In order to design the injury risk curves, numerical simulations and sled tests were scheduled. Simulation activities were divided into two phases:
• Pre-crash phase: to analyze the movement of the occupant by using human body models (HBM). Braking maneuvers were also performed with the same objective.
• Crash phase: to analyze the occupants’ injuries by using both HIII dummy model and human body models.

   

Some results from the simulation activities were obtained recently. Unexpectedly, crash phase results with a HIII dummy model do not show an important benefit when reducing impact speed. However, crash phase simulations with HBM are currently being performed in order to validate the results.
Testing activities will probably be performed at the beginning of next year.