Fig 1.
Overview of the PIPER scalable HBM.
(a) Model with skeleton and internal organs exposed; (b) Positioning of the HBM with the PIPER tool; (c) Personalization (scaling) of the HBM with the PIPER tool.
Fig 2.
The PIPER generalized car environment model v1.0.
This model consists of all relevant components of a generic vehicle for use in impact simulations.
Table 1.
Values assigned to the parametric environment model to reproduce the vehicles of Case 2012, 2017 and 2043.
Only the rear and front seat were used in simulations.
Fig 3.
CRS models used for the FE simulations.
(a) CRS model for children between 9-18 Kg or of age between 9 months and 4 years; (b) CRS model for children between 15-25 Kg or of age between 4 and 6 years.
Table 2.
Values assigned to the parametric CRS model (group 2) to reproduce the CRS of Case 2017 and 2043.
Case 2017 involved a child sitting on a low back booster. Therefore, backrest height and rotation values are not applicable (N/A).
Fig 4.
Virtual sensors implemented in the PIPER scalable HBM.
(a) Location of the accelerometers to measure head, chest and pelvis acceleration; (b) constrained interpolation of nodes referred to the T9 coordinate system for measuring chest displacement in the sagittal plane; (c) constrained interpolation of nodes referred to the T9 coordinate system for measuring chest displacement in the lateral plane; (d) node sets to measure right, frontal and left abdominal force.
Fig 5.
Comparison between the scaled and positioned HBM in the simplified environment and the respective Q-dummy in the physical accident reconstruction.
(a) Case 2012; (b) Case 2017; (c) Case 2043.
Fig 6.
Example of how kinematics chains for positioning were estimated from available documentation of Case 2017.
Similar procedures were used for Case 2012 and Case 2043. Rotations of body parts along the Y direction were sufficient to position the HBM close to the Q-dummy.
Table 3.
Angle values used for positioning of the PIPER scalable HBM.
Rotations of frames were performed relatively to the y-axis of the world frame. Also, joint rotation was performed along the y-axis of the joint frame.
Fig 7.
Comparison of the kinematics of the HBM during computer simulation (top) and the dummy during physical accident reconstruction (bottom) for Case 2012.
The images in the top row were captured at 71 ms (left), 104 ms (middle) and 137 ms (right) respectively and the HBM kinetics during the simulated entire impact is provided in S1 Movie.
Fig 8.
Comparison of the kinematics of the HBM during computer simulation (top) and the dummy during physical accident reconstruction (bottom) for Case 2017.
The images in the top row were captured at 70 ms (left), 96 ms (middle) and 217 ms (right) respectively and the HBM kinetics during the simulated entire impact is provided in S2 Movie.
Fig 9.
Comparison of the kinematics of the HBM during computer simulation (top) and the dummy during physical accident reconstruction (bottom) for Case 2043.
The images in the top row were captured at 60 ms (left), 81 ms (middle) and 260 ms (right) respectively and the HBM kinetics during the simulated entire impact is provided in S3 Movie.
Fig 10.
Comparison between the resultant accelerations of head, thorax and chest in the HBMs (dashed black lines) and dummies (full red lines) for all the performed accident reconstructions.
Both the HBM and Q-dummy curves were processed by a low-pass Butterworth filter using the same cutoff frequency of 180 Hz.
Fig 11.
Comparison between the upper neck force, upper neck momentum and chest deflection in the HBMs (dashed black lines) and dummies (full red lines) for all the performed accident reconstructions.
Both the HBM and Q-dummy curves were processed by a low-pass Butterworth filter using the same cutoff frequency of 180 Hz. The large chest displacement measured in the Q-dummy in Case 2012 appeared to be some noise.
Fig 12.
Maps of von Mises stress in the skull (unit is GPa in the legend), first principal strain in the brain, and maximum shear strain in the cervical disk that sustained injury in the real accident.