Simulation of Submarining Risk in Reclined Seating Positions

Autonomous driving will be part of tomorrow's mobility, but it also poses challenges for vehicle safety. As the problems associated with comfort seating positions in autonomous vehicles, for example, are fundamentally new, simulation with human body models (HBM) is a logical option.

In this context, CDH AG has analysed comfort seating positions with 45° and 60° recline angles and compares the results of a THUMS V7 human body model with those calculated using a modified ATD-MODELS THOR 50M dummy model. The comparison focusses on the risk assessment of submarining. Current research results show an increase in this risk as the backrest angle increases. In its Vision 2030, the consumer protection organisation EuroNCAP has published the goal of evaluating comfort seat positions with the help of virtual testing, i.e. finite element simulation.

In frontal crash sled simulations, both models confirm known problems of reclined seating positions. The reduced effectiveness of the seatbelt system leads to higher forward displacements, accompanied by a tendency to submarining. The shoulder belt slides upwards and makes contact with the neck. Overall, a standard seat and restraint system does not offer sufficient protection potential for the changed seating positions. Although the human and dummy models show the same problem areas, there are clear differences in the kinematics of the models as a whole as well as individual body parts. In particular, the pelvic kinematics, which are important for assessing the risk of submarining, are different, resulting in different interaction with the lap belt.

The results of the study demonstrate the need to further investigate the biomechanics of the human body in comfort seating positions.

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