Authors: B. Wade von Kleeck, Juliette Caffrey, Ashley A. Weaver, and F. Scott Gayzik—Biomedical Engineering, Wake Forest University School of Medicine; Jason Hallman—Toyota Motor North America R&D
Abstract
The increased use of computational human models in evaluation of safety systems demands greater attention to best practices in coupling the model to its seated environment. This study assessed the THUMS v4.0.1 in an upright driver posture and a reclined occupant posture. Each posture was gravity settled into an NCAC vehicle model to assess model quality and HBM to seat coupling.
HBM to seat contact friction and seat stiffness were varied across a range of potential inputs to evaluate over a range of potential inputs. Gravity settling was also performed with and without constraints on the pelvis to move towards the target H-Point. These combinations resulted in 18 simulations per posture, run for 800 ms. In addition, 4 high speed crash pulse simulations were run to assess the effect of settling time on driver kinematics. HBM mesh quality and HBM to seat coupling metrics were compared at kinetically identical time points during the simulation to an end state where kinetic energy was near zero.
A gravity settling time of 400 ms was found to be optimal for both the upright driver posture and the reclined occupant posture. The pelvis constrained approach was recommended for the upright driver posture and was not recommended for the reclined occupant posture. A gravity settling time of 400 ms was sufficient to gravity settle both postures to match the quality metrics of the 800 ms gravity settled time. Driver kinematics were found to be a function of settling time with the greatest head and chest excursions observed at the approximately 400 ms timepoint.
Keywords: Vehicle Safety, Human Body Models, Gravity Settling, Passive Safety
Type: Full Paper