Research and/ or Engineering Questions/ Objective

In the event of an accident, in today's vehicle belt, airbag systems and steering columns absorb the kinetic energy of occupants in front crashes. Most steering columns are equipped with a deformation device, which provides limited forward displacement of the steering wheel when being impacted dynamically by the occupant. As these features perform on fixed force levels, they deform less when loaded with lower energy, so e.g. when impacted by a smaller occupant. So especially for small occupants the maximum available forward displacement is not used, so they will be decelerated on a higher g-levels than needed.
Student researchers of Trier University of Applied Sciences, Germany, and Hindustan Institute of Technology and Sciences, India, started a joint research program with support of the German DAAD and investigated solution to provide maximum forward displacement for occupants of all sizes. This solution could improve vehicle safety significantly in Western markets with in average larger people (correlating approx. with 50%ile dummy) as well as Asian markets with an in average smaller population (correlating approx. with 5%ile dummy).

Methodology

In current legislation, safety systems such as the steering column must be validated in tests using 50%ile Hybrid III dummies only. A component simulation model with a standard restraint system was set up using HyperMesh and LS-Dyna to investigate kinematics and injury pattern for all available dummy sizes (5-50-95%ile). For the steering column a damping device was developed allowing adaptive force levels with help of magnetorheological fluids.

Results

Various load levels could be developed for the different dummy sizes. The kinetic energy thus could be dissipated over a longer distance so occupant injuries have been reduced. Feasibility studies on the advanced damper have proven the potential of the approach.

Limitations of this study

To date, there is no technical implementation to determine the exact mass of an occupant in a vehicle, therefore only the seat position can be used as indicator for the mass and size. Nevertheless, a progressive absorption characteristic is included which will not load the occupants more than in today's systems.

What does the paper offer that is new in the field including in comparison to other work by the authors?

Magnetorheological fluids suffer of the problem of sedimentation, so their usage in rarely used restraint systems is critical. The design presented will ensure high level of dilution throughout the vehicle life, what is unique in the market. The solution thus can improve safety for a wide range of occupants in passenger cars and helps minimize or even prevent injuries.

Conclusions

The method provides a general approach for an efficient way of improving occupant safety over a wide range of occupant sizes.

Mr. Felix Bentgens, Trier University of Applied Sciences, GERMANY; Prof. Dr.-Ing. Peter Koenig, Trier University of Applied Sciences, GERMANY; Mr. Marco Mueller, Trier University of Applied Sciences, GERMANY; Dr. Jaikumar Mayakrishnan, Hindustan Institute of Technology & Science, INDIA; Mr. Raghavendran Pala Raviramachandran, Hindustan Institute of Technology & Science, INDIA